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An Optimal Camera Monitor System (OCMS) to Improve the Visibility Performance and Safety of Commercial Vehicles and Trucks | Similar to Passenger Vehicles (PV), Commercial Vehicles and Trucks (ComVecT) use standard rearview mirrors to improve the visibility of the surrounding environment and facilitate a safer maneuvering of large vehicles. Standard rearview mirrors used in ComVecT are large and flat to cover outside areas as specified in theFMVSS 111 standard, or other requirements like ECE-R46. In addition, ComVecT are also equipped with optional mirrors with different Field of View (FoV), such as wide angle, look-down cross proximity, and front mirrors. These optional mirrors cover wider or specific areas around the vehicle which might not be possible otherwise with standard mirrors only. While these mirrors tend to enhance the visibility around the truck, they create undesirable blind zones to the driver. These blind zones can be gaps between the direct vision through the windows and indirect vision provided by the mirror. These can also be invisible areas occluded by the vehicle structure and hidden to the driver. Or, these can be obstructed areas concealed behind the mirror. In this paper, we demonstrate the feasibility and design of an Optimal Camera Monitor System (OCMS) to ideally eliminate the blind zones around the ComVecT with the goal of enhancing the driver visibility. We show that blind zones occur naturally due to the vehicle structure and large dimensions; number of mirrors used and mirror sizes. The optimal design takes into consideration not only the position, FoV, and resolution of the camera, but also the position, size, and resolution of the display inside the vehicle. The optimal design takes also into consideration human constraints like driver position and visual acuity of the human eye. |
Interior Noise Design of a Light Rail Vehicle Using Statistical Energy Analysis | This paper addresses the NVH design of a light rail vehicle whose maximum allowable interior SPL levels at certain speeds are regulated and may vary between countries, states, and cities. The objective of this study was to predict sound pressure levels (SPL) at several interior locations across a wide range of frequencies and estimate if the current design configuration will meet the noise level limits. Statistical Energy Analysis (SEA) was used to predict interior SPL and to understand and rank the various noise contribution paths and give a better understanding of the physics of transmission and what types of design changes are most effective to reduce the overall interior SPL to meet targets. A typical light rail vehicle is composed of a frame-like structure covered by lightweight panels and with interior panels that are increasingly made from composites, sandwich, laminated, or honeycomb materials or extruded panels. These lightweight structures made from materials that have previously been used primarily in aerospace applications have modal characteristics and transmission properties that require more advanced modeling than for simpler monolithic panels. Evaluation of the dominant noise transmission paths from the dominant sources allows sensitivity studies to evaluate which noise paths are the best candidates for improvement to overall vehicle NVH and which parts may be candidates for cost and weight reduction without significant degradation of the acoustic performance. This paper describes the motivation for this study and the details of the light rail vehicle construction. The SEA modeling approach is discussed, including the modeling of the structures and the main contributing sources. The contribution path ranking and the interior SPL predicted by the SEA model at several target locations are presented and compared to measured interior SPL data. Conclusions about the results and recommendations for future work are given. |
Application of Near-field Acoustic Holography to Low Temperature Engine Start-up Noise Issue Resolution | An issue of engine squealing in low temperature range (around −25°C) right after start-up emerged for a significant number of vehicles in a vehicle program. The earlier effort had focused on typical common culprits such as the pulley-belt systems etc. However, much effort, by subjective listening and guestimating hardware replacement, yielded no fruitful results for more than a year. The application of near-field acoustic holography on top of the engine in a climate chamber quickly identified several noise source locations. Further noise source identification effort on top, front and left side of the engine pinpointed the top three noise source locations: the idler pulley and water pump on front, the air compressor on right side, and the air intake throttle on top. Then a series of experiments were subsequently conducted, leading to a conclusion that the idler pulley was the source of the issue. Finally, investigation of the pulley system confirmed that the insufficient lubricating capacity at low temperature was the root cause. By switching to a type of lower base oil viscosity lubricating grease characterized by lower rotation torque in cold temperature conditions, the issue was successfully resolved. |
MMLV: NVH Sound Package Development and Full Vehicle Testing | The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-1 vehicle design, comprised of commercially available materials and production processes, achieved a 364 kg (23.5%) full vehicle mass reduction, enabling the application of a 1-liter 3-cylinder engine resulting in a significant environmental benefit and fuel reduction. This paper includes details associated with the noise, vibration and harshness (NVH) sound package design and testing. Lightweight design actions on radiating panels enclosing the vehicle cabin typically cause vehicle interior acoustic degradation due to the reduction of panel surface mass. To reduce this deficiency, an MMLV vehicle sound package development was conducted to improve NVH performance of MMLV with ultra-light weight sound package technologies. The project goal was to improve acoustical performance of MMLV by 2 dB without increasing the total sound package weight of “Vehicle A” which is the baseline vehicle for MMLV. This paper presents the lightweight sound package development process for MMLV as well as the full vehicle NVH test results in the high frequency range of 200-10000 Hz. Floor damping treatment strategy and body NVH test results in the low frequency range are also discussed. Full vehicle SEA (Statistical Energy Analysis) simulations are used to evaluate and guide the design and development of MMLV sound package. The final MMLV vehicle sound package design improves the vehicle's engine noise reduction (ENR) by 3.3 dB and improves the front tire patch noise reduction (TPNR) by 1.2 dB without increasing the baseline sound package weight. |
A Virtual ECU and Its Application to Control System Analysis - Power Window System Demonstration | A virtual power window control system was built in order to look into and demonstrate applications of microcontroller models. A virtual ECU simulated microcontroller hardware operations. The microcontroller program, which was written in binary digital codes, was executed step-by-step as the virtual ECU simulation went on. Thus, production-ready codes of ECUs are of primary interest in this research. The mechanical system of the power window, the DC motor to lift the window glass, the H-bridge MOSFET drivers, and the current sensing circuit to detect window locking are also modeled. This means that the hardware system of the control system was precisely modeled in terms of mechanical and circuit components. By integrating these models into continuous and discrete co-simulation, the power window control system was analyzed in detail from the microscopic command execution of the microcontroller to the macroscopic motion of the window mechanism altogether. The minute microcontroller operation in a few nanosecond time span and slower window lifting were observed in the same time traces. Obviously, the accuracy and the simulation time of the co-simulation were a trade-off. In this paper the techniques to deal with the causes of the timing errors in co-simulation were discussed. Possible use of this technology includes detailed analysis of control operation and verification of the fail-safe response to component failures. As the co-simulation includes both the control system hardware in component level and the control software in execution format, components failures are easily injected in any level. This work was one of the outcomes of the vECU-MBD WG (Virtual ECU Model-Based Development Working Group) in Japan. |
Anti-Pinch Mechanism for Power Window | New generation automobiles are equipped with power windows which eases the passenger’s effort in moving the vehicle windows up and down. Many of them are stuffed with advanced features like automatic up/down option for ensuring functionality with a single press of the switch. Even though it adds comfort to driver & passenger, inadvertent use of power window can be fatal if a person’s body part gets trapped inside. An effective solution for this problem is anti-pinch mechanism, which releases the object safely just when it gets trapped. It detects the object trapped and immediately moves the window down so that trapped object will get released easily. The anti-pinch algorithm used in this project is based on the “Method of Monitoring Movable Element”, method monitor traveling distance of a power window pane. In order to achieve this different from conventional techniques we are using Ultrasonic sensor. The anti-pinch technology of power window has to meet standards issued by EU and United States. The maximum force a power window is allowed to exert on any object is 100N. Compliance with this limit must be monitored and enforced in a range of 4mm to 100mm from the top window frame, which is successfully meet by prototype designed. The goal of this project is to provide ultimate protection from power window injuries by implementing this simple & effective safety system to vehicles which are already running on road. Compactness & independent functionality ensures great compliance of this accessory with existing power windows. |
Windows Opening Influence on the Drag Coefficient of a Hatchback Vehicle | Aerodynamics plays a key role in nowadays vehicle development, aiming efficiency on fuel consumption, which leads to a green technology. Several initiatives around the world are regulating emissions and efficiency of vehicles such as EURO for European Marketing and the INOVAR Auto Project to be implemented in Brazil on 2017. In order to meet requirements in terms of performance, especially on aerodynamics, automakers are focusing on aero-efficient exterior designs and also adding deflectors, covers, active spoilers and several other features to meet the drag coefficient. Usually, the aerodynamics properties of a vehicle are measured in both CFD simulations and wind tunnels, which provide controlled conditions for the test that could be easily reproduced. During the real operations conditions, external factors can affect the flow over the vehicle such as cross wind in open highways. The aerodynamic behavior of the vehicle can also be affected by the influence of the user such as by opening the windows in order to cool down the cabin, which is the main topic of this paper. In this work, 12 different window-opening combinations are presented and the drag values compared with a baseline model, considering fully closed windows. The study was conducted using CFD simulations of a current production hatchback vehicle, with two passenger inside and full interior cabin representation. Results show drag increment for all presented cases, compared with baseline configuration, which also implies in fuel consumption increase. Further studies on cabin cooling effects and passenger’s thermal comfort are conducted in order to complement this paper. |
Design Optimization of Vehicle Body NVH Performance Based on Dynamic Response Analysis | Noise-vibration-harshness (NVH) design optimization problems have become major concerns in the vehicle product development process. The Body-in-White (BIW) plays an important role in determining the dynamic characteristics of vehicle system during the concept design phase. Finite Element (FE) models are commonly used for vehicle design. However, even though the speed of computers has been increased a lot, the simulation of FE models is still too time-consuming due to the increase in model complexity. For complex systems, like vehicle body structures, the numerous design variables and constraints make the FE simulations based optimization design inefficient. This calls for the development of a systematic and efficient approach that can effectively perform optimization to further improve the NVH performance, while satisfying the stringent design constraints. In the present work, an efficient method to optimize the structural dynamic response is proposed considering the low-frequency NVH performances. As a first step, to reduce computational burden, a response sensitivity analysis is performed to detect the most important variables prior to the design optimization. Then an analytical approximation model of vibration resonance peak is constructed and coupled with the adaptive simulated annealing (ASA) algorithm to replace the time-consuming finite element analysis. Subsequently, an optimization of NVH performance considering dynamic response is formulated and carried out. The methodology aims at improving the NVH behavior of body structure by simultaneously suppressing several resonance peaks. Finally, the proposed method and its process are successfully illustrated through a vehicle body example. The results demonstrate that the proposed method of incorporating response surface model with ASA algorithm is feasible and cost-efficient in solving the vibration optimization problem. |
Modelling Techniques for Noise and Vibration Control of the Body and Chassis | The basic function of a motorcycle frame is somewhat similar to that of the skeleton in the human body, i.e. to hold together the different parts in one rigid structure. One of the major benefits (for a motorcycle enthusiast) of using an advanced frame design lies in the sporty handling characteristics of the bike. A well designed frame can add to the joy of riding a motorcycle as the bike would feel more stable, effortless, and confident around corners, in straight lines and while braking. A well approved modeling [2] techniques or adequate guide line principles have to be followed while designing the body and chassis in order to achieve the vibration within control. This paper depicts a methodological right approach (guide lines) while designing the body and chassis of a two wheeler in order to control noise and vibration of the body and chassis. |
Optimization of Bushing Stiffness Using Numerical Approximation Model to Improve Automotive NVH Performance | An efficient method to determine optimal bushing stiffness for improving noise and vibration of passenger cars is developed. In general, a passenger vehicle includes various bushings to connect body and chassis systems. These bushings control forces transferred between the systems. Noise and vibration of a vehicle are mainly caused by the forces from powertrain (engine and transmission) and road excitation. If bushings transfer less force to the body, levels of noise and vibration will be decreased. In order to manage the forces, bushing stiffness plays an important role. Therefore, it is required to properly design bushing stiffness when developing passenger vehicles. In the development process of a vehicle, bushing stiffness is decided in the early stage (before the test of an actual vehicle) and it is not validated until the test is performed. If it turns out that vehicle performances are not satisfied in the test, another test with bushing changed needs to be conducted, which requires additional costs. Several tests are usually performed to identify bushings which achieve target performances. In addition, the decision of bushing stiffness is complicated since there is typically a conflict between requirements for bushing stiffness from various vehicle performances, such as ride, handling, noise, and vibration. Therefore, in the design stage, the validation of bushing stiffness is desirable to save costs of the vehicle development and ensure the performances of the vehicle. In this paper, a novel optimization methodology based on a numerical approximation model is presented. This method is used to determine optimal stiffness values of bushings in a vehicle for improving the vehicle noise. By using the method, it is found that bushing stiffness is well optimized while reducing the noise. |
Characteristics of Non-Stationary Sources of Wind Noise Measured with a Surface Pressure Array | Measurements of interior wind noise sound pressure level have shown that dBA and Loudness are not adequate metrics of wind noise sound quality due to non-stationary characteristics such as temporal modulation and impulse. A surface microphone array with high spatio-temporal resolution has been used to measure and analyze the corresponding non-stationary characteristics of the exterior aero-acoustic loading. Wavenumber filtering is used to observe the unsteady character of the low wavenumber aero-acoustic loading components most likely to be exciting glass vibration and transmitting sound. |
A Research on the Sound Quality Contribution of Vehicle Body Panel | Sound quality of vehicle interior noise affects passenger comfort. In order to improve the sound quality of a micro commercial vehicle, the vehicle interior noise under different conditions such as idle, constant speeds and accelerating is recorded by using artificial head with dual microphones. The sound quality of recorded noise is evaluated in both objective and subjective ways. Physical parameters of interior noise are calculated objectively, and annoyance score is analyzed subjectively using paired-comparison method. According to the regression analyzing of the annoyance score and the physical parameters, an objective evaluation parameter of the sound quality is employed. To analyze the vehicle body panel contribution to interior noise sound quality, the location and spectrum characteristics of major panel emission noise sources are identified based on partial singular valued decomposition (PSVD) method. By investigating the contribution of each noise sources to the sound quality evaluation formula, the dominant interior noise source is determined. That provides technical support for subsequent research on improving the sound quality of vehicles. |
Evaluation on the Solar Reduction Glass in an Electric Vehicle by Experimental Measurements in a Climate Chamber | Solar energy through glass windows has an influence on the thermal environment in the cabin and thermal comfort of occupants. A medium-size electric vehicle (EV) is conducted for evaluating the performance of solar reduction glass under summer conditions in the climate chamber by experimental measurements. For this purpose, two kinds of glass are attached to the medium-size EV with different performance of solar reduction rate (IR-cut type and normal type). In this paper, two types of experimental measurements, steady state and unsteady state conditions, are conducted. Surface temperature, air temperature and electric consumption of air conditioner are measured under some conditions of air-conditioner. EHT (Equivalent Homogeneous Temperature) by thermal manikin, thermal sensation and thermal comfort by male and female subjects are also measured. Significant difference in the measured surface temperature of the instrument panel where solar radiation reaches through the glass window is found between IR-Cut glass and normal glass. In addition, one or two rank difference in the thermal comfort at the part where solar radiation reaches is found, and “hot” thermal sensation and discomfort in the female subject is much improved. Heat load of the air conditioner can be decreased by 20% from the view point of controlling the air conditioner by thermal comfort of the occupants. The solar reduction glass such as IR-cut glass has a significant influence on the thermal sensation, thermal comfort of car occupants and electric consumption of EV. |
Identification of Vibro-Acoustic Coupled Modes for Vehicle | In performing noise control design for vehicles, there is a benefit to identifying important vibro-acoustic coupled mode. The purpose of this study is “identifying the coupled mode of a vehicle through FRF (frequency response function) measurement”. A speaker which measure the internal acoustic pressure was used as a new experimental method. An acoustic input is estimated by the fluctuation of the acoustic pressure inside the speaker box. Acoustic pressures are measured by using some microphones, the vibrations of the structure are measured by using some accelerometers. Main experiment was carried out for measure the vibro-acoustic mode. First acoustic mode was identified in about 66 Hz. And structure associated mode with this mode was identified. Hence, the vibro-acoustic mode identification was carried out. |
Experimental Determination of Acoustic Cavity Resonances of Vehicle Sub-Systems | The present quiet and comfortable automobiles are the result of years of research carried out by NVH engineers across the world. Extensive studies helped engineers to attenuate the noise generated by major sources such as engine, transmission, driveline and road excitations to a considerable extent, which made other noise sources such as intake, exhaust and tire perceivable inside. Many active and passive methods are available to reduce the effect of said noise sources, but enough care needs to be taken at the design level itself to eliminate the effect of cavity resonances. Experimental investigation of cavity resonances of real systems is necessary besides the FEA model based calculations. Acoustic cavity resonance of vehicle sub systems show their presence in the interior noise through structure borne and air borne excitations. Cavity resonances for some systems e.g. intake can only be suppressed through resonators. The exact location and nature of acoustic cavity resonance needs to be found as accurately as possible to bring out the best from a resonator. Different approaches are used to excite and identify the cavity resonances depending on the operational differences of various systems. Cabin cavity modes are analyzed by arranging an array of microphones inside the cabin and exciting the cavity with help of a low frequency volume acceleration source. The cavity modes of inflated tire are analyzed by placing accelerometers circumferentially and exciting the cavity by intermittent deflation. The cavity resonances of intake system are investigated using microphones by providing excitation through a low frequency volume acceleration source. Acoustic modal analysis is carried out to identify and understand the mode shapes. |
Method for Measuring and Analyzing Transient Powertrain Vibrations of Hybrid Electric Vehicles on an Acoustic Roller Test Bench | In terms of customer requirements, driving comfort is an important evaluation criterion. Regarding hybrid electric vehicles (HEVs), maneuver-based measurements are necessary to analyze this comfort characteristic [1]. Such measurements can be performed on acoustic roller test benches, yielding time efficient and reproducible results. Due to full hybrid vehicles’ various operation modes, new noise and vibration phenomena can occur. The Noise Vibration Harshness (NVH) performance of such vehicles can be influenced by transient powertrain vibrations e.g. by the starting and stopping of the internal combustion engine in different driving conditions. The paper at hand shows a methodical procedure to measure and analyze the NVH of HEVs in different driving conditions. In order to investigate the influence of noise and vibrations by restarting and stopping the internal combustion engine (ICE) (like switching between electric and hybrid driving or the start-stop function) on the driver, acoustic and vibration measurements are performed inside the vehicle. A binaural artificial head is used to examine the acoustic effects on the vehicle interior noise. The vibration behavior is analyzed using acceleration sensors at defined measurement positions. Regarding the human perception of the NVH performance, characteristic values, related to the vibrational response of the vehicle, are needed for a vehicle evaluation. By combining the measurement data of the transient powertrain vibrations with evaluation approaches (ISO 2631-1, DIN EN 61672-1, spectrograms using Fourier transform (FFT) and subsequent psychoacoustic criteria) a frequency-dependent vibration analysis is performed. The analysis, depending on measurements on an acoustic roller test bench, supports the development of HEVs’ NVH performance, regarding the perceived driving comfort by the customer. |
Analysis of Gear Rattle Noise and Vibration Characteristics Using Relative Approaches | Noise signals of the driver’s right ear include those of engine, environment, chassis dynamometer, loaded gears and unloaded gears when they are recorded in full vehicle on chassis dynamometer in semi-anechoic room. Gear rattle noise signals of the driver’s right ear caused by unloaded gear pairs can’t be identified or quantified directly. To solve the problems, relative approaches are used to identify and quantify the gear rattle noise signals. Firstly, the rattle noise signals of the driver’s right ear are filtered by human ear characteristic functions and steady noise signals are extracted by regression and smoothing processes. The noise signals are regressed at 200ms interval in the hearing critical frequency bands and smoothed in the flanking frequencies. Then, the noise relative approaches are obtained by subtracting the steady noise signals from the filtered noise signals, which are the transient noise signals of the unloaded gear pairs inducing the rattle noise. Finally, the occurrence time, frequency and level of the rattle noise are obtained from the noise relative approaches. Through this method, ten rattle noise signals of the highest relative approaches are identified within 3.5 s in the full vehicle test. The results show that the occurrence time obtained by the rattle noise relative approaches is entirely coincided with that of the ten rattle noise signals which is recorded in the raw noise signals playback. The results of the rattle noise identification are consistent with that of the subjective perception. Thus the gear rattle noise is identified accurately. The interference of the noise signals of the engine, the chassis dynamometer, the environment and the loaded gears is effectively removed by the noise relative approaches to avoid false diagnosis. Gear rattle vibration signals on transmission housing obtained in the full vehicle test are similar to those of the rattle noise. Therefore, the occurrence time, frequency and level of the rattle vibration also can be obtained by the relative approaches. Results show that bigger relative approach represents higher gear rattle noise and vibration level. The gear rattle vibration signals of the transmission housing always coincide with all the rattle noise signals of the driver’s right ear which delay the rattle vibration signals for 0.01∼0.04 s. Thus the transmission housing is the major transfer pathway of the gear rattle noise. The frequency range of the gear rattle noise is within that of the rattle vibration because of the noise transfer function from the transmission housing to the driver’s right ear. The gear rattle vibration characteristics of each surface and direction are different. Therefore, the rattle anisotropy can be considered when rattle mechanism is investigated. The rattle vibration of the upper, front and left surfaces on the transmission housing is higher than other surfaces. Those three surfaces are the major improvement targets for optimization of the rattle performance. |
A Multiproduct Multimaterial Solution for Lightweight Vehicle Doors | Light weighting of vehicle doors is a challenge faced by all vehicle manufacturers - whether passenger cars and vans or large commercial vehicles like trucks and buses. This need is driven not only by the desire to improve the vehicle's fuel economy, but also by the implication of the doors on the buyer's perception of the vehicle's quality. The best solutions to these needs emerge from an unbiased consideration of different materials and product forms in the design and development of lightweight doors. To demonstrate this notion, a truck door was designed that has the potential of providing both improved fit as well as enhanced structural performance. The concept also simplifies the manufacturing process thereby minimizing system cost while offering approximately 7% additional weight saving compared the door already made from light weight materials (aluminum). This paper describes the design concept for lightweight vehicle doors using aluminum in its various product forms as well as other materials. |
Development of Power Sliding Door (PSD) System with Push-Pull Cable Driving Method | We have developed a power sliding door (PSD) system driven by a push-pull cable. The door closure and slide are operated by different actuators to limit the force required for a compact, light-weight drive unit. This paper introduces the concept of the PSD system using a push-pull cable drive. Two new technologies to achieve the PSD system are also described. One is the door position control for increasing the push-pull cable reliability. The other is a compact position sensor to accurately detect the sliding door's position. |
Door Open Overload: Margin and Flushness Approach | Since doors are repeatedly used by vehicle owner, they have a great influence on his or her perception of vehicle quality. The door open overload is an abusive load requirement for customer usage. The doors must withstand loads which force the door open against its stop, leading to concern over the effects of permanent set to the functioning of the door system and the margins/ flushness. Traditionally, the CAE is utilized to objectively evaluate the deflections and permanent set at the door latch to evaluate door open overload requirement. In this study, the FEA methodology has been applied to expand the scope beyond traditional method to simulate door open overload condition. The change in the margin and flushness due to the permanent set are evaluated using nonlinear analysis (ABAQUS). The results show that the method helps designers to ensure the door meets the margin/flushness criteria for door open overload condition during early stage of the door design process. |
Experimental Assessment Of Door Window Glass Smooth Operation And Tracking | Since the door glass windows are used regularly, they have a great influence on the vehicle owner's perception of vehicle quality. Today's customers demand that moveable door window glass operates smoothly. Experimental methods have been developed to evaluate window glass smoothness and positional stability. This paper presents experimental results that quantify the chattering and positional stability of the window glass. For window glass smooth operation and tracking, the measurements were taken on glass chatter, glass velocity, motor current, motor voltage, and glass stall force. The change in glass position was measured on the vehicle during several stages of four poster durability testing to evaluate window glass positional stability during road induced vibrations. Using these experimental methods, the designers should be able to evaluate several window glass functional requirements and achieve cost/time savings. |
Sled System Requirements for the Analysis of Side Impact Thoracic Injury Criteria and Occupant Protection | This paper discusses struck-side occupant thoracic response to side-impact loading and the requirements of a sled system capable of reproducing the relevant motions of a laterally impacted vehicle. A simplified viscoelastic representation of a thorax is used to evaluate the effect of the door velocity-time profile on injury criteria and on the internal stress state of the thorax. Simulations using a prescribed door velocity-time profile (punch impact) are contrasted against simulations using a constant-velocity impact (Heidelberg-type impact). It is found that the stress distribution and magnitude within the thorax, in addition to the maximum thorax compression and viscous response, depend not only on the door-occupant closing velocity, but also on the shape of the door velocity-time profile throughout the time of contact with the occupant. A sled system capable of properly reproducing side-impact door and seat motion is described. |
Analysis and Design of Slow Build Studies During Sheet Metal Assembly Validations | Several manufacturers are adopting six sigma programs in efforts to reduce stamping variation. This requires the crucial step of establishing dimensional relationships for the stamping dimensional outputs that become key process inputs to the assembly process. This paper describes a methodology used to determine the root cause of dimensional changes in a front door assembly. Among the key findings in this study are the importance of understanding the effects of the datum-locating scheme and the significant influence of assembly processing variables, rather than stamping variability, on the final door assembly dimensional quality. |
Parametric study of side impact thoracic injury criteria using the MADYMO human body model | This paper presents a computational study of the effects of three parameters on the resulting thoracic injury criteria in side impacts. The parameters evaluated are a) door velocity-time (V-t) profile, b) door interior padding modulus, and c) initial door-to-occupant offset. Regardless of pad modulus, initial offset, or the criterion used to assess injury, higher peak door velocity is shown to correspond with more severe injury. Injury outcome is not, however, found to be sensitive to the door velocity at the time of first occupant contact. A larger initial offset generally is found to result in lower injury, even when the larger offset results in a higher door velocity at occupant contact, because the increased offset results in contact later in the door V-t profile - closer to the point at which the door velocity begins to decrease. Cases of contradictory injury criteria trends are identified, particularly in response to changes in the pad modulus. Maximum chest deflection and maximum viscous criterion gradually decrease as the padding modulus increases. TTI, however, increases with some increases in pad modulus. Complex interactions among the three parameters are observed, and their interpretation is shown to depend on the specific injury criterion analyzed. |
Evaluation of Variation in the Excursion Measured in the FMVSS 226 Ejection Mitigation Test Resulting from Test Vehicle Setup | Federal Motor Vehicle Safety Standard 226 outlines a component test methodology that consists of a linear impact test that uses a featureless head-form with a mass of 18 kg to impact a vehicle's side windows' daylight openings at various positions. The test measures the excursion of the head-form beyond the plane of the window glazing. The intention is to evaluate the ability of a vehicle's ejection mitigation system, such as the curtain airbag or other vehicle features, to manage the impactor energy and limit excursion. However, there are several factors which may cause variation in the amount of excursion measured in the test. These factors include how the vehicle is restrained for the test, the friction of the linear impactor shaft and the lateral deflection of the impactor shaft among others. This paper will present background information from a previous study on variability involving the impactor shaft as well as a study which identifies the effects of vehicle restraint on the excursion measured in the Federal Motor Vehicle Safety Standard (FMVSS) 226 test. |
Structural-Acoustic Analysis of Vehicle Body Panel Participation to Interior Acoustic Boom Noise | A structural-acoustic finite element model of an automotive vehicle is developed and applied to evaluate the effect of structural and acoustic modifications to reduce low-frequency ‘boom’ noise in the passenger compartment. The structural-acoustic model is developed from a trimmed body structural model that is coupled with an acoustic model of the passenger compartment and trunk cavities. The interior noise response is computed for shaker excitation loads at the powertrain mount attachment locations on the body. The body panel and modal participation diagrams at the peak response frequencies are evaluated. A polar diagram identifies the dominant body panel contributions to the ‘boom’ noise. A modal participation diagram determines the body modes that contribute to the ‘boom’ noise. Finally, structural and acoustic modifications are evaluated to determine their effect on reducing the ‘boom’ noise and on the overall lower-frequency sound pressure level response. |
NVH Improvement for Three Wheeler | In India, demand for three wheelers with low noise is increasing among the customers thereby the noise reduction of three wheelers is necessary. In order to overcome the demand in the market, manufactures are giving more importance to noise levels at passenger ear level and driver ear level. In test vehicle it was found that engine is the main noise source, biggest challenge was to reduce noise transfer from engine compartment to passenger and driver ear. In three wheelers it is more difficult as there is no close cabin. This paper main objective is to reduce noise levels at driver and passenger ear level. The objective and subjective evaluations of both vehicles were carried out to identify the levels at driver ear level and passenger ear level. First task was to find out noise sources in engine. Most dominating noise source was tappet and flywheel area. Modifications were done on tappet cover and flywheel cover to reduce noise levels. Different techniques were used in this project like partial enclosure of engine, modifications in vehicle engine compartment. The result shows reduction in sound levels at passenger and driver ear level in modified vehicle comparing with old vehicle. |
Use of Statistical Energy Analysis in Vehicle NVH Design Cycle | Statistical Energy Analysis (SEA) is used to predict high-frequency acoustic and vibration response in vehicle NVH design. Early in the design cycle prototype hardware is not yet available for testing and the geometry is still too poorly defined and changing too quickly for Finite Element Analysis or Boundary Element Analysis to be an effective NVH analysis tool. For most of the concept phase and early design phase, SEA uniquely offers the ability to virtually predict the main noise transfer paths and to support target setting for component and full vehicle NVH design. At later stages of the design process, SEA combines with NVH testing to provide more accurate predictions and to provide guidance for more efficient testing. This paper describes the established uses of SEA in the vehicle industry and presents an overview of the NVH design cycle and how SEA is used to support NVH development at different stages. The synergy between SEA analysis and full-vehicle and component-level NVH testing is discussed. The types of testing that most effectively validate the SEA models and the methodology for validating the models are presented. Case studies for several vehicle NVH applications are presented with examples of the use of SEA prediction and validation measurements. Overall advantages, limitations, and use of SEA to increase the efficiency of the NVH development test effort are summarized. |
Acoustical Performance of Baffle Design Options for Water Management | Expandable cavity sealers have become a critical component of the overall acoustic package that contributes to the documented noise reduction in passenger car applications over the course of the last twenty years. They encompass a variety of technologies, some of which are delivered into the supply chain as bulk materials and others which are highly engineered parts and assemblies. As the market for smaller and more fuel efficient vehicles continues to expand, design architectures of the base vehicle platforms are evolving to include body designs with smaller spaces between adjacent layers of sheet metal. As this space, or cavity, between the adjacent layers of sheet metal is shrinking, the complexity of components that must be integrated into the space between these layers of steel is increasing. Complex arrays of airbags, corresponding wire harnesses, and water management tools are now standard requirements in the design process. To manage the complexity of these lightweight and fuel efficient vehicle architectures, new engineering design solutions are required to meet stringent acoustic requirements. The supply base of acoustic products to the automotive OEMs has also matured over this time period, creating a very competitive environment, both regionally and globally. Design solutions that go beyond the basic functionality of a cavity filler are becoming more common. This paper will evaluate a recent design challenge presented by an OEM to improve visibility for the driver. Here, the hardware to direct water drainage is moved from outside the windshield pillar cavity body metal to inside the cavity metal. A new cavity filler solution is conceptualized to manage this unique packaging and acoustic performance need. Although it's in its infancy, the solution, along with other means of water management, are measured for Insertion Loss and compared. This initial study supports the promise for acoustic performance of a solution that does not exist in the market today. |
ULSAC - Lightweight Steel Automotive Closures | Following the success of the UltraLight Steel Auto Body (ULSAB) in 1997, the UltraLight Steel Auto Closure (ULSAC) Consortium representing steel producers from all over the world was founded. Porsche Engineering Services, Inc. (PES) was commissioned to conduct a concept study for the development of UltraLight Steel Auto Closure concept designs for all types of automotive closures that were structurally sound at affordable cost. The Validation Phase began in November 1998. In spring 2000, the ULSAC DH Door Structures featuring stamped Door Outer Panels were built and tested for structural performance, dent resistance and oil canning. The tested doors show state-of-the-art structural performance compared to today's frameless door structures, and the mass reduction ranges from 22 to 42% compared to the normalized mass of benchmarked doors. In the Validation Phase, a cost model was developed and the cost to produce the ULSAC frameless door structure was calculated. The results of this cost estimation show that the ULSAC door can be manufactured in high-volume production with no cost penalty. |
Dimensional Management - Setting Static and Dynamic Dimensional Goals Concurrently | The main element of dimensional management is specification cascading where customer requirements are translated into dimensional targets. It also includes GD&T, datum strategy, and tolerance optimization. These elements can only be effective if all of the work is done concurrently among various disciplines of an organization that have a stake in the fit, finish, and performance of the final product. When setting static dimensional goals during product development, vehicle performance targets and dynamic goals have to be defined simultaneously. One example is of the final door appearance for gaps and flushness on an automotive body from static standpoint. The wind-noise and door flutter are examples of dynamic performance goals. It becomes very costly to fix static fit and finish issues caused by the dynamic state of the vehicle late into the product development cycle or at the customer locations. |
Developing a Sonar-Assisted Device for the Blind | At Wake Forest University, Winston-Salem, NC, a biology professor researching echolocation in bats teamed up with an associate professor of computer science and an interdisciplinary team of students to develop a device that can help the visually impaired navigate better. Their research focused on developing a device that could be worn like a watch by a visually-impaired person as a supplement to other aids like a cane or guide dog. |
Automotive Engineering: May 2018 | Testing for cold-climate comfort AE goes way north to the Arctic Circle for an inside look at Hyundai's winter testing of the new Nexo FCV and Kona EV and their unique and critical HVAC systems. Innovation more than skin deep A new wave of engineered plastics are delivering structural, mass-reducing, and aesthetic benefits for new vehicle applications. A secret weapon for roof-crush testing Before you crush that bus or racecar chassis, find out how engineers at CAPE are optimizing test-rig performance. Editorial: Tesla's Model 3 is two very different cars SAE Standards News A hive of activity Supplier Eye Why aren't there more unibody pickups? The Navigator We can't trust humans to supervise machines Acura and ArcelorMittal debut world-first hot-stamped door ring system on 2019 RDX Powertrain analyst: Light-vehicle fleet needs big gains to meet tightening emissions regs Toyota unveils more gasoline ICEs with 40% efficiency IAV using 3D-printed pistons for engine testing 2018 Kona debuts Hyundai's new B-SUV platform Nissan variable-compression engine gets first shot at volume with new 2019 Altima Q&A Honeywell's Geoff Duff talks turbos |
Windshield Defrosting Systems Test Procedure and Performance Requirements—Trucks, Buses, and Multipurpose Vehicles | This SAE Recommended Practice establishes uniform test procedures and performance requirements for the defrosting system of enclosed cab trucks, buses, and multipurpose vehicles. It is limited to a test that can be conducted on uniform test equipment in commercially available laboratory facilities. Current engineering practice prescribes that for laboratory evaluation of defroster systems, an ice coating of known thickness be applied to the windshield and left- and right-hand side windows to provide more uniform and repeatable test results, even though under actual conditions such a coating would necessarily be scraped off before driving. The test condition, therefore, represents a more severe condition than the actual condition, where the defroster system must merely be capable of maintaining a cleared viewing area. Because of the special nature of the operation of most of these vehicles (where vehicles are generally kept in a garage or warmed up before driving) and since defrosting under steady-state over-the-road operations is the main concern, test conditions have been adopted which assume that the engine is warm before the vehicle is driven. There are two options for producing hot coolant in this recommended practice. Testing using these two approaches on the same vehicle will not necessarily provide identical results. Many vehicle models are offered with optional engines, and each engine has varying coolant temperatures and flow rates. If the test is being conducted to compare the performance of one defroster design to another defroster design, then the external coolant source approach (Test A) will yield the most comparable results. If the test is being conducted to validate the defroster installation on a specific vehicle model with a specific engine, then using the engine to heat the coolant (Test B) will be more appropriate. This document will be reviewed and revised as technological progress in vehicle defroster test procedure requires. |
Road Noise Identification and Reduction Measures | In a scenario where cost and weight targets are becoming critical, we tend to produce lighter and more powerful vehicles. In this context, NVH becomes one of crucial parameters in overall performance delivery. Other than power train, road induced noise also becomes an important parameter within vehicle development. Predecessor vehicle is body over frame structure and here a monocoque vehicle is considered for study. Different techniques like transfer path analysis, vibro-acoustic modal analysis, operational deflection shapes are used to identify the major force paths, radiating panels and their sensitivity to noise at operator ear location. Simulation model of body is built with good correlation and input forces are given at different attachment points to predict the noise levels. This combined approach helped us in reducing the overall noise level at certain constant speed by 4 dB(A) and also with great ease. All recommendations from this exercise are implemented |
Vehicle Airborne Noise Analysis Using the Energy Finite Element Method | The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving numerically governing differential equations with energy densities as primary variables. In this paper a complete simulation process for evaluating airborne noise in an automotive vehicle is presented and validated through extensive comparison to test data. The theoretical elements associated with the important paths of the noise transfer from the exterior of the vehicle to the interior acoustic space are discussed. The steps required for developing an EFEA model for a vehicle are presented. The model is developed based on the physical construction of the vehicle system and no test measurements are utilized for adjusting the numerical model. An acoustic noise source is placed at each one of four vehicle locations (engine compartment, front left tire patch, rear left tire patch, and exhaust) where typical exterior noise sources are present in an operating vehicle. The exterior acoustic field is evaluated numerically by the Energy Boundary Element Analysis (EBEA). The acoustic loading from each source is applied on all of the outer parts of the vehicle EFEA model and the interior noise level is computed in the frequency range of 200Hz - 8,000Hz. Predictions for the interior noise level (expressed in a noise reduction format) are compared with test results for all four excitations. The ability of the EFEA method to conduct a panel contribution analysis is used for identifying the panels which contribute the most to the power flow from the structure to the interior acoustic space. Such information is useful in making design decisions when implementing noise mitigation strategies. |
A Software Library for Active Control of Automotive Engine Noise | A general-purpose software solution for active control of engine noise within vehicle cabins is described. The feed-forward system, based on FxLMS algorithm, reduces engine orders below 150 Hz by emitting independent control signals from one or more loudspeakers in the cabin, and uses one or more microphones inside the cabin to monitor noise levels and adapt control filters. The software solution is a C/C++ callable library with floating-point and fixed-point versions, which would normally be ported to a DSP or application processor situated in the head-unit or power amplifier of the audio/infotainment system. We provide a comparative analysis of our integrated software library versus a mass-production solution in a Honda Odyssey, which shows that the software library, with a very reasonable computational complexity, provides a low-cost alternative to a dedicated ANC system whilst achieving comparable performance and robustness. |
Correlation of Dominant Noise Transfer Paths in Statistical Energy Analysis Vehicle Model from Test as Basis for Variant Vehicle Development | For purposes of reducing development time, cost and risk, the majority of new vehicles are derived strongly or at least generally from a surrogate vehicle, often of the same general size or body style. Previous test data and lessons learned can be applied as a starting point for design of the new vehicle, especially at early phases of the design before definite design decisions have been finalized and before prototype of production test hardware is available. This is true as well of vehicle NVH development where most new vehicles being developed are variants of existing vehicles for which the main noise transfer paths from sources of interest are already understood via test results and existing targets. The NVH targets for new vehicles are defined via benchmarking, market considerations, and other higher-level decisions. The objective is then to bridge the gap between test data from surrogate vehicles to direct support of the NVH development of new vehicle programs. Because of its strength in providing analysis predictions of the effect of design changes on vehicle NVH at higher frequencies, Statistical Energy Analysis (SEA) is an established tool for using available test data to correlate an SEA model that can be adapted for early design phase NVH development of new vehicles. The effect of changes to materials, gage thickness, sound package, source levels, or geometry changes on the interior noise levels can be predicted by SEA with good accuracy to support design decisions that must be made early in the program. This paper illustrates with a concrete example an idealized implementation of this process. The main test plan design considerations for a baseline surrogate vehicle are discussed. Some key test results and their uses are presented. The updating and correlation of an SEA model representing the baseline vehicle are shown. The objective methods for determining the effectiveness of the correlation are given using this vehicle as an example. Finally, the use of a correlated SEA model to effectively support the NVH development of several variant vehicle programs at an early phase of the design process is presented along with suggestions for the best use of this design tool, its advantages and limitations, and the most effective roles it can serve to support the overall vehicle design cycle. |
Ventilation Improvement in a Non-AC Bus | Ventilation is a crucial factor affecting passenger comfort in any vehicle. In a non-air-conditioned bus, ventilation caters to the dual requirement of fresh breathing air as well as providing a cooling sensation by enhanced evaporation of sweat. The higher the velocity of air around the passengers, the greater the cooling effect experienced by them. The ventilation mechanism of a non-air-conditioned bus is primarily the air flow through the windows due to relative motion between the bus and the air around it. This paper describes studies carried out to identify the right combination of open windows which would provide optimum air flow at the passenger head level plane in a bus. A bus model with 12 windows, 6 on each side is used for the study and air velocity at certain points in the head level plane, arising out of different combination of window openings is evaluated using CFD. The minimum value of velocity observed among the points, which is indicative of the minimum level of comfort provided by the combination, is compared for different combinations of openings and the optimum identified. Since a comparison of all possible combinations would involve evaluating 312 CFD runs, Design of Experiments (DOE) is used to obtain the optimum using a reduced number of analyses. Through this study it is attempted to place windows only at few strategic locations that would contribute to optimum air flow at all points within the bus by eliminating the non contributing windows without reduction in passenger comfort, thereby changing bus design philosophies and providing greater freedom in bus design. The optimum configuration of windows was found to provide ∼17% reduction in window area. |
Active Noise Control for the 4.0 TFSI with Cylinder on Demand Technology in Audi's S-Series | To significantly increase fuel efficiency while keeping power and performance of its signature S models, AUDI developed a new 4.0 TFSI engine with Cylinder on Demand technology and introduced it with its new S6, S7 and S8 models. To manage upcoming NVH issues due to this new technology and keep the intended sporty V8 note of the engine under all operating conditions, a broad range of new and advanced technologies was introduced with these vehicles. This paper focusses on the Active Noise Control system and its development. It describes the ANC system from a control theory perspective in addition to the acoustical perspective. Special features of the system include the availability of multiple tunings (4/8 cylinder mode) to support the specific overall sound character and the fast switching process as switching between different cylinder configurations might be as fast as 300 ms. In addition, the system also includes specific features that allow an advanced audio system diagnosis. Last but not least, some aspects of the development process will be highlighted. |
Further Development of Velocity-based Airborne TPA: Scan & Paint TPA as a Fast Tool for Sound Source Ranking | The interior noise of a car is a general quality index for many OEM manufacturers. A reliable method for sound source ranking is often required in order to improve the acoustic performance. The final goal is to reduce the noise at some positions inside the car with the minimum impact on costs and weight. Although different methodologies for sound source localization (like beamforming or p-p sound intensity) are available on the market, those pressure-based measurement methods are not very suitable for such a complex environment. Apart from scientific considerations any methodology should be also “friendly” in term of cost, time and background knowledge required for post-processing. In this paper a novel approach for sound source localization is studied based on the direct measurement of the acoustic particle velocity distribution close to the surface. An airborne transfer path analysis is then performed to rank the sound pressure contribution from each sound source. The method called “Scan & Paint TPA” makes use of only one probe that is swept along the surface. The reciprocal transfer functions are measured by a second sweep with the same probe and a monopole sound source in the driving position. A new methodology for applying “Scan & Paint TPA” in a complex acoustic environment is given along with an experimental validation in a car interior. |
Functional Vehicle Design for Urban Mobility | When approaching new mobility solutions such as car-sharing, it soon becomes apparent that it may be necessary to develop specific vehicles for this application. In this paper, Applus IDIADA explains its experience in the development of the iShare, an electric vehicle conceived as a demonstrator of our complete vehicle development capabilities following the principle of “development led by functionalities”, with the consideration that it would be used in open car-sharing fleets running according to the MIT's (Massachusetts Institute of Technology) “mobility-on-demand” concept. This paper explains the process followed in order to reach the definition of the different parts, systems and components that are the result of the consideration of the Technical Functionalities, such as Active Safely, Passive Safely, Driveability, NVH, Fleet Management, Maintenance and Comfort, that in their turn result from the basic vehicle specifications defined from the analysis of the key functionalities of this vehicle that are suitability for the car-sharing business model and the mobility requirements of the potential customers. In particular, the paper includes details about the vehicle layout analysis and why a 4-wheel and 2-parallel seats configuration was chosen instead of 2- o 3-wheel or 2-tandem seats configuration, the powertrain, steering, suspension, braking, Passive Safety and energy efficiency concepts explored, the process allowing a customer to book and have access to a given vehicle without a physical key and finally the systems to allow the car-sharing operator to keep the cars in good conditions by replacing interior and exterior trims easily and inexpensively and recycling the materials to make new trims out of it. |
Seat Squeak Measurement and Diagnosis | BSR (Buzz, Squeak and Rattle) is one of the oldest concerns in automobiles which directly reflect the build, assembly and manufacturing quality of a vehicle. In a cabin all the areas where there is relative motion between two components, such as trims, instrument panel and seats, are prone to squeak. This paper explains the study of seat squeak measurement and diagnosis which is a major concern for one of the products which is already in the market. Since squeak is a friction induced non stationary phenomenon, lot of effort was required to generate squeak in both component as well as vehicle level. At component level, electrodynamic shaker was extensively used for generation of squeak signals. In Vehicle level, driving through different road patterns, pave track and forced excitation on four posters are performed for generation of squeak signals. In this paper usage of wavelet and Zwikker loudness are explained for the diagnosis of seat squeak to identify the problematic frequencies. Results in both pave track condition and in four poster excitation method are presented. |
Multidisciplinary Design Optimization of a Hatchback Structure | Lightweight automobile has an important role in saving the energy, improving the fuel economy and reducing the exhaust emission. However, reducing the mass of the automobile need to meet the structural and NVH (Noise, Vibration and Harshness) performance requirements. With the rapid development of Computer Aided Engineering (CAE) technology, more and more people tend to research the complex engineering application problem by computer simulation. An important challenge in today's simulation is the Multidisciplinary Design Optimization (MDO) of an automobile, including mass, stiffness and modal etc. This paper presents a MDO study in a minicar hatchback. The aim of the study is to minimize the mass of the hatchback while meeting the following requirements: (1) Structural performance. the bending stiffness is higher than the original data and the sagging residual deformation is less than the original data. (2) NVH performance. the lowest natural vibrational frequency is higher than the original data. The sample points are obtained by the Design of Experiment (DOE) with optimal Latin Hypercube and the approximation models of mass, modal, bending stiffness, sagging are established with polynomial response surface method. The thicknesses of the major components in the hatchback are selected as design variables. The approximation models are optimized by sequential quadratic programming method. A good agreement between the predictive values of the approximation and the results of finite element simulation with the error less than 5% is demonstrated. The predictive values of the approximation meet the engineering requirement. Consequently, the optimized results have higher accuracy. In the process of the optimization design, the weight of the hatchback reduced by 6.5% and the new hatchback meets all the prescribed requirements about structural and NVH performance. |
Effect of Glazing Thermal Conductivity on Cabin Soak Temperature | Previous papers by the present authors described use of computational fluid dynamics (CFD) to quantify the effect of glazing thermal conductivity on steady-state heating, ventilation and air-conditioning (HVAC) load under wide-ranging climate and state of motion scenarios, and to estimate the significance of this effect for electric battery performance. The CFD simulations yielded the total heat transfer between the ambient and the cabin of a model car, including radiative and convective heat transfer. The five-fold lower inherent thermal conductivity of polycarbonate relative to glass was found to reduce steady-state HVAC load by several percent in all scenarios, leading to reduced greenhouse gas emission or increased electric range, according to the type of vehicle. This paper complements the previous study by quantifying through simulation the effect of glazing thermal conductivity on cabin soak temperature, the latter reflecting a balance between radiative and convective heat transfer in a closed, unventilated, parked car with HVAC off, in a hot, sunny environment. Soak temperature has been a focus in the regulatory arena as an initial condition in proposed tests of air-conditioning contribution to tailpipe emissions. Two glazing configurations are simulated: a baseline configuration with glass at all locations, and a reduced thermal conductivity configuration with polycarbonate glazing substituted at the backlite and rooflite. A difference in soak temperature of less than 1°C is found for the two glazing configurations under the conditions of relatively high solar radiation and ambient temperature in Phoenix, Arizona at mid-day in June. This difference is small compared to both the soak temperature relative to the ambient and the variation in soak temperature found for a range of optical and heat transfer parameters for non-glazing elements of the cabin. The insignificance of glazing thermal conductivity for soak temperature is reconciled with its significance for steady state HVAC load in terms of air movement at the inside and outside glazing surfaces. |
A Development of Smart Ventilation System | There are some problems “windows fog up a lot” for ventilation system. We have Test Development Procedure to prevent the fog problems. But, Many fog problems occurred in the cars that we made. So in this paper, new ventilation system is needed and developed. The Smart Ventilation System automatically controls indoor air quality even though the blower motor is off. There are two sensors that is used for AutoDefogSensor system and CO2 CONTROL system.. The sensor is on when blower motor and heater control is off. We use these signals and make new ventilation logics. We evaluate this system in chamber & '13 winter test in USA. |
Development of an Acoustic Material Database for Vehicle Interior Trims | Characterizing the acoustic properties of sound-absorbing materials is costly and time consuming. The acoustic material database helps the automotive designers design their interior trims in accordance with target level for interior noise. In this paper, a two-microphone impedance tube was used to measure the normal sound absorption coefficient. The main parameters that are used in the theoretical model for interior noise level assessment are investigated. These parameters include thickness, airflow resistivity, porosity, tortuosity, viscous and thermal characteristics length. The measured results have been validated by the theoretical models. The validation of normal sound absorption coefficient was found to be in agreement with its corresponding measurement data. Finally, the sensitivity of the sound absorption coefficient which is related to the physical properties mentioned above is further analyzed. |
Optimal Design of Vehicle Dash and Floor Sound Package Based on Statistical Energy Analysis | An increasing demand for vehicle noise control has been proposed and at the same time, vehicle weight and fuel economy have become critical for the automotive industry. The methodology of statistical energy analysis (SEA) is used to balance both light weight and high noise insulation performance. In this paper, the vehicle dash and floor sound package systems, which are two of the major paths for vehicle interior noise, are studied and optimized by CAE and testing technology. Two types of sound packages which are the conventional insulation system and the lightweight one are chosen for the vehicle dash and floor system. The vehicle dash and floor systems are modeled by SEA and the transmission loss (TL) of the dash and floor system is analyzed, respectively. Several influence factors of the TL are also analyzed, such as sound package coverage, the leaks, etc. The results of the TL analysis show that under certain sound package coverage or leaks, the TL of the dash and floor system with the conventional sound package is a little larger than the TL with the lightweight one. However, the lightweight sound package system has better absorption property and the advantage of weight reduction. Meanwhile, the full vehicle SEA model is built up and the noise transfer path is analyzed. By using the full vehicle noise reduction tests, the full vehicle SEA model and the main noise transfer paths are validated. Then, the vehicle exterior sound pressure levels (SPL) are tested under several load cases inside a semi-anechoic chamber. By applying the vehicle exterior SPLs to the full vehicle SEA model, the correlations are performed between the simulation and tests. Finally, the sound package systems of the dash and floor are analyzed and optimized by the full vehicle CAE and testing analysis. |
Scientists Build Thinnest-Possible LEDs To Be Stronger, More Energy Efficient | Most modern electronics, from flat-screen TVs and smartphones to wearable technologies and computer monitors, use tiny light-emitting diodes, or LEDs. These LEDs are based on semiconductors that emit light with the movement of electrons. As devices get smaller and faster, there is more demand for semiconductors that are tinier, stronger and more energy efficient. |
SUPPLIER EYE | Are you innovating for NVH? I'll never forget the experience, as a kid, of lifting the massive steel hood of my father's 1971 Dodge Monaco and seeing nothing but V8 engine and a few rubber hoses. The vast compartment was so uncluttered, I could look straight down and see the pavement. By comparison, the view under today's vehicle hoods reveals a dense landscape of technologies aimed at acoustic control: covers, shields and insulators designed to keep injector clatter, induction honk and even pulley whirl muffled. Supplier innovations are central to winning the ongoing war with NVH-noise, vibration and harshness. The battle started decades ago and will certainly increase in the future. This is an engineering realm with numerous tradeoffs involving total piece cost, capital cost, stranded fixed capital, tooling complexity/count, system optimization, flexibility, intellectual property and even downstream warranty. But because NVH (more accurately, the lack of it) has direct impact on the end customer, it has become a commitment rather than an option across vehicle segments. |
Lincoln unveils Big-SUV future with Navigator concept | Intent on staying on its message of reinvigorating its brand under the banner of “quiet luxury,” Ford's premium-vehicle unit, Lincoln, used the 2016 New York auto show to reveal what almost certainly will be remembered as one of the most audacious concept cars ever, the Lincoln Navigator Concept. Two stupendously-sized gullwing doors lift to allow full access to the SUV's first and second seating rows, with 30-position adjustable seats “floating” on pedestal attachments that eliminate traditional seat tracks, full-length “concertina” steps are power-deployed to create a waterfall of steps for entry and exit, and a “wardrobe management system” in the cargo area looks like something Tony Stark dreamed up to secure his Iron Man gear. |
Autonomous Robotic Manipulation (ARM) | Autonomous robotic manipulators have the potential to increase manufacturing efficiency, provide in-home care, and reduce the risk to humans in hazardous situations. The current challenge in autonomous robotic manipulation is to approach the capabilities of dedicated, one-off manipulators in known environments with versatile, inexpensive, and ubiquitous manipulator systems that can operate in a range of environments with only high-level human input. |
Dual-Compartment Inflatable Suitlock | There is a need for an improvement over current NASA Extravehicular Activity (EVA) technology. The technology must allow the capacity for quicker, more efficient egress/ingress, allow for “shirtsleeve” suit maintenance, be compact in transport, and be applicable to environments ranging from planetary surface (partial-g) to orbital or deep space zero-g environments. The technology must also be resistant to dust and other foreign contaminants that may be present on or around a planetary surface. The technology should be portable, and be capable of docking with a variety of habitats, ports, stations, vehicles, and other pressurized modules. |
The Thermal Hogan — A Means of Surviving the Lunar Night | A document describes the Thermal Hogan, a new shelter concept that would be used on the Moon to moderate the extreme nighttime temperatures, allowing survival of equipment with minimal heater power. It is lightweight, has few mechanical parts, and would be relatively easy to deploy on the Moon. |
Dual-Compartment Inflatable Suitlock | A paper discusses a dual-compartment inflatable suitlock (DCIS) for Extra-vehicular Activity (EVA) that will allow for dust control, suit maintenance, and efficient EVA egress/ingress. The expandable (inflatable technologies) aspect of the design will allow the unit to stow in a compact package for transport. |
Wearable, Artificially Intelligent, Bionic Device | eLEGS is a wearable, artificially intelligent, bionic device that enables people with paralysis to stand up and walk again. The exoskeleton is battery-powered and rechargeable, fitting comfortably and securely over clothing. |
Microcontroller Based Low Cost Illumination Control and Warning System | This paper demonstrates the design, development and validation techniques for the vehicle illumination control system typically used for emerging market applications with limited program variable costs and more features needs to be packed in a controller module. The system, powered by an 8-bit RISC Harvard microcontroller, controls the in-car illumination by triggered time delay and a PWM controlled theatre-dimming effect for predefined duration. It further alarms the driver and co-driver if the exterior lamps are left ON and doors opened. The module is packed on a 30 mm square base with height 50 mm and mounted in the CJB. The paper concludes with a generic methodology for designing such robust systems for the cost and quality conscious automotive society. |
The Design of an Acoustics Laboratory for Off-Highway, Heavy Truck, and Recreational Vehicles | The new Blachford Acoustics Laboratory was designed specifically for acoustical testing of large vehicles, such as off-highway machines, recreational vehicles, and heavy trucks. While there are many automotive and architectural test laboratories for which a new laboratory can be based, there are very few acoustics laboratories capable of testing these larger vehicles. However, by drawing on the experience with the previous Blachford Laboratory, several off-highway manufacturers' test facilities, and the newer automotive manufacturer and supplier laboratories, a functional and cost effective design was developed. This design features indoor and outdoor test areas, including a large hemi-anechoic chamber equipped with a chassis dynamometer, a reverberation room with several transmission loss openings, work rooms, office areas, and a 10 meter radius outdoor drive-by pad. Special design considerations included door size, component test opening dimensions, dynamometer axle and floor loading capabilities, cooling and exhaust extraction flow rates, and special electrical connections. In addition, the site chosen for the laboratory also provided many challenges. |
Wavelet-Based Visualization, Separation, and Synthesis Tools for Sound Quality of Impulsive Noises | Recent applied mathematics research on the properties of the invertible shift-invariant discrete wavelet transform has produced new ways to visualize, separate, and synthesize impulsive sounds, such as thuds, slaps, taps, knocks, and rattles. These new methods can be used to examine the joint time-frequency characteristics of a sound, to select individual components based on their time-frequency localization, to quantify the components, and to synthesize new sounds from the selected components. The new tools will be presented in a non-mathematical way illustrated by two real-life sound quality problems, extracting the impulsive components of a windshield wiper sound, and analyzing a door closing-induced rattle. |
Interior Fittings – A Global View | In today's global economy, the automotive design engineer's responsibilities are made more complex by the differences between regulatory requirements of the various global markets. This paper compares instrument panel head impact requirements of FMVSS 201 with its European counterparts, ECE 21, and EEC/74/60, Interior Fittings. It describes the similarities and differences between these regulations and explains the unique requirements for each market. It then compares processes for development and validation testing in both markets. It also covers related topics like self-certification, witness testing, radii, projections, and interior compartment doors. The cockpit design engineer will gain an understanding of the factors involved in ensuring that their design fully meets the requirements of the subject regulations. |
Use of Acoustical Holography for Efficient 3D Measurement in Car Interiors | A continuously growing demand comes from the automotive industry for optimization of materials and sound insulating product packaging inside the car, so as to propose the best acoustic performance at reduced costs. A new acoustical holography system provides part of the solution to meet such a demand. The capability of measuring the acoustic field inside a vehicle with high spatial resolution makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings and interior components in various environmental conditions (acoustic chamber, on road, in wind tunnel). The method allows for: Detailed localization of noise sources or leaks, Knowledge of the acoustic energy distribution on elementary surfaces (such as doors, windscreen, roof, sealing components, …), Reconstruction of the energy radiated by elementary surfaces in order to predict the acoustic pressure at driver's and passengers' ears, Introduction of local modifications on subsystems and components in order to predict their effect on the acoustic field. In conjunction with some numerical prediction methods, this technique will allow to apply integrated acoustic engineering design methods for a complete understanding and control of the large variety of components and systems involved in the car performance. |
Automotive Body Structure Enhancement for Buzz, Squeak and Rattle | Today, the interior noise perceived by the occupants is becoming an important factor driving the design standards for the design of most of the interior assemblies in an automotive vehicle. Buzz, Squeak and Rattle (BSR) is a major contributor towards the perceived noise of annoyance to the vehicle occupants. An automotive vehicle consists of many assemblies such as instrumentation panel, doors, sun/moon-roof, deck lids, hood, etc. which are the potential sources of BSR noise. The potential locations of critical BSR noise could be contained within such assemblies as well as across their boundaries. An extensive study is made regarding the overall structural behavior as well as their interaction under typical road loads to come up with enhanced design for improved quality from the BSR noise perspective. The alternative designs were comparatively evaluated for their relative noise level from buzz, squeak and rattle perspective using an analytical tool - N-hance.BSR. Critical noise sources both at the system as well as the assembly levels were identified and the relative noise levels were compared critically to determine the influence of the design changes on the BSR quality of the system and its assemblies. In this paper, a brief introduction is provided regarding the typical product background and the noise quality requirements, typical design changes that influence the BSR characteristics followed by a brief introduction to the software N-hance.BSR. The results of such a comparative design evaluation from N-hance.BSR are presented at the end. The observations of the critical squeak and rattle locations were confirmed by physical tests on the baseline and enhanced models. |
Model Based System Development in Automotive | The paper presents a major part of the STEP-X project (Structured Development Process by the example of X-By-Wire-Application in the automotive), namely a seamless, model based software development process in automotive engineering. Our process is model based and supported by a tool chain. The tool DOORS is used for requirements management and engineering whereas the CASE tool Artisan RtS based on the Unified Modeling Language (UML) and the CASE tool Ascet SD are used for specification and design purposes. Each of these tools has its particular strength in a certain design phase. We propose designing rules and modeling guidelines for the development of state based behavior which conforms to seamless model transformation in our tool chain. The rules are checked by an embedded rule-checker. Additionally we illustrate our approach in a case study on a subsystem of the Volkswagen car electronics. The case study is characterized by state-oriented and concurrent behavior as well as time and value-discrete information processing. |
Challenges in Vibroacoustic Vehicle Body Simulation Including Uncertainties | During the last decades, big steps have been taken towards a realistic simulation of NVH (Noise Vibration Harshness) behavior of vehicles using the Finite Element (FE) method. The quality of these computation models has been substantially increased and the accessible frequency range has been widened. Nevertheless, to perform a reliable prediction of the vehicle vibroacoustic behavior, the consideration of uncertainties is crucial. With this approach there are many challenges on the way to valid and useful simulation models and they can be divided into three areas: the input uncertainties, the propagation of uncertainties through the FE model and finally the statistical output quantities. Each of them must be investigated to choose sufficient methods for a valid and fast prediction of vehicle body vibroacoustics. It can be shown by rough estimation that dimensionality of the corresponding random space for different types of uncertainty is tremendously high. Therefore, a substantial reduction of the dimensionality is crucial. Next important step is to choose a proper method to model uncertainties and include them in the FE model. Here, many different methods are available: From well-known sampling based methods like Monte-Carlo to more sophisticated spectral methods like generalized Polynomial Chaos. Finally, the output of these simulations is not a single deterministic value but rather completely new results like mean value, variance and probability distribution. Therefore, the mindset has to change from comparing single deterministic curves and values to an evaluation of stochastic quantities and their relations. This new kind of output requires dealing with new demands as well as a new mindset from simulation engineers. |
Concept Study on Windshield Actuation for Active Control of Wind Noise in a Passenger Car | The windshield is an integral part of almost every modern passenger car. Combined with current developments in the automotive industry such as electrification and the integration of lightweight material systems, the reduction of interior noise caused by stochastic and transient wind excitation is deemed to be an increasing challenge for future NVH measures. Active control systems have proven to be a viable alternative compared to traditional passive NVH measures in different areas. However, for windshield actuation there are neither comparative studies nor actually established actuation concepts available to the automotive industry. This paper illustrates a comparative conceptual study on windshield actuation for the active control of wind noise in a passenger car. Making use of an experimental modal analysis of the windshield installed in a medium-sized vehicle, a reduced order numerical simulation model is derived. Possible actuation concepts are briefly recapitulated and a comparative, preliminary study assists the selection of possible actuation positions of the windshield. Two basic actuation concepts (i.e. an electrodynamic inertial mass actuator as well as windshield actuation by means of piezo-electric stack actuators) are investigated in detail and generalized design requirements are derived for both actuator types. |
High Frequency Vibration Transmission Analysis on Agricultural Tractor by Using Combined Dynamical Energy Analysis and Transfer Path Analysis Approach | Dynamical Energy Analysis (DEA) has recently been introduced as a mesh-based high frequency method modelling structure borne sound for complex built-up structures. Using DEA, the structure-borne sound of an assembled agricultural tractor was calculated and good agreement between measurement and DEA calculations has been shown. However, it is still difficult to model a solid structure as currently DEA is based on wave-transmission calculations through plates and plate-to-plate junctions. Additionally, it is often difficult to generate accurate FE meshes of assembled complex structures because of welds, bolts, and rubber brushes between components. In this paper, we propose a novel method to generate DEA elements based on measurement data in order to model solid parts of a complex structures. The method of Advanced Transfer Path Analysis (ATPA) is employed to extract energy-transmission characteristics of a structure. Firstly, Frequency Response Functions (FRFs) are measured between interface points on a structure. Then the direct transfer functions between all interface points are calculated using ATPA. Finally, DEA elements connecting interface points are calculated. They are based on the ATPA result and therefore represent energy-transmission characteristics of the structure. the proposed method is applied to an agricultural tractor structure in order to generate DEA-TPA elements of a gear casing demonstrating the effectiveness of the proposed method. |
Vibration Energy Harvesting Damper in Vehicle Suspension | The road roughness is one of the main sources of a severe undesired vehicle vibration. The vehicle suspensions are the front lines of defense protecting the passengers and vehicle equipment from harsh vibrations caused by the ground road roughness. The recent tendency is to combine the process of vibration mitigation and additional electrical power generation. It allows scavenge the power from a vehicle’s vibrations and convert these vibrations into electrical power for use in vehicle systems. New Vibration Energy Harvesting Damper (VEHD) is based on author’s US Patents and consists of two main components: Tuned Mass Damper with automatic self-tuning properties and Generator of Electricity. The analysis of dynamical performance and effectiveness of developed rectilinear VEHD for Jeep Sport Wrangler vehicle suspensions is presented. Mathematical model of dynamical behavior is developed and the simulation analysis illustrates the direction of optimal parameter’s selection for getting VEHD with minimal mass. Test results demonstrate the efficiency of proposed VEHD and some new opportunities for their applications in vehicle suspensions. |
Evaluation and Improvement of Greenhouse Wind Noise of a SGMW SUV using Simulation Driven Design | At SAIC-GM-Wuling (SGMW) the greenhouse wind noise performance of their vehicles has gained a lot of attention in the development process. In order to evaluate and improve the noise quality of a newly developed SUV a digital simulation based process has been employed during the early stage of the design. CFD simulation was used for obtaining the flow induced exterior noise sources. Performance metrics for the quality were based on interior noise levels which were calculated from the exterior sources using a SEA approach for the noise transmission through the glass panels and propagation to the driver’s or passenger’s head space. Detailed analysis of the CFD results allowed to identify noise sources and related flow structures. Based on this analysis, design modifications were then applied and tested in a sequential iterative process. As a result an improvement of more than 2 dB in overall sound pressure level could be achieved. |
CFD Water Management Design for a Passenger Coach with Correlation | Side window clarity and its effect on side mirror visibility plays a major role in driver comfort. Driving in inclement weather conditions such as rain can be stressful, and having optimal visibility under these conditions is ideal. However, extreme conditions can overwhelm exterior water management devices, resulting in rivulets of water flowing over the a-pillar and onto the vehicle’s side glass. Once on the side glass, these rivulets and the pooling of water they feed, can significantly impair the driver’s ability to see the side mirror and to see outwardly when in situations such as changing lanes. Designing exterior water management features of a vehicle is a challenging exercise, as traditionally, physical testing methods first require a full-scale vehicle for evaluations to be possible. Additionally, common water management devices such as grooves and channels often have undesirable aesthetic, drag, and wind noise implications. Being able to detect water management issues such as A-pillar overflow, as well as to develop strategies to resolve them in parallel with early design cycle exterior aerodynamic development, is highly desirable for this reason. This paper details a collaborative effort where a CFD method is first validated against on road testing and then applied to a design study. The Lattice Boltzmann code based results presented show an excellent correlation with on-road test data. One successive design variants is created, with the design process being driven by the understanding provided by the CFD results. |
Enhancing Driver Awareness Using See-Through Technology | This paper presents a real-time application of see-through technology using computer vision (e.g., object detection) and Vehicle-to-X (V2X) communication (e.g., Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I)). Each access point (AP) was connected to Chattanooga’s fiber optics internet, supporting a data transfer rate up to 10-Gbps. Using a 5Ghz frequency, vehicular communications were set up with a seamless handover for transferring real-time data. Two web cameras acting as clients were mounted on the windshield of two of three vehicles to send image data to the offsite server. Using multi-threaded programming, both image feeds were processed simultaneously. Once the server received the images, it performed an object recognition algorithm on each image using a convolutional neural network (CNN). Post- identification, the images from the second vehicle were sent and overlaid dynamically to the third vehicle’s image. This repetitive overlapping of images allowed the third vehicle to “see-through” the second vehicle in real-time. This experiment was showcased during the US Ignite Smart Cities Summit in June 2017 to emphasize the benefits of drivers being able to “see-through” the car in front to make more intelligent decisions when passing a vehicle, stopping for a pedestrian, or seeing an upcoming detour due to construction before the view is within their line of sight. Using V2X communication with computer vision gives the driver a higher level of awareness and allows better decision making in the case of a roadway conflict, ultimately increasing the level of safety on our roadways. |
Application of CAE (Computer Aided Engineering) Superelement Technique for NVH (Noise, Vibration and Harshness) Attributes on a Trimmed-Body Vehicle Structure in Order to Assist Supplier Commodity Development Based Also on NVH Requirements | The business environment is ever changing, several innovations have allowed companies to transcend borderlines and become global entities. While the opportunities are numerous so are the challenges. In this fiercely competitive global marketplace, success requires companies to pay closer attention to supplier relations. The relationship between an automotive industry and its suppliers is an example of it, so the application of CAE (Computer Aided Engineering) superelement technique may improve, in terms of NVH (Noise, Vibration and Harshness), the vehicle development efficiency, without compromising confidentiality directives. Most of NVH requirements must be tracked through Transfer Functions (TFs) analyses at response points located on the Trimmed-Body Finite Element Model (FEM), as for example: Point Mobility, Vibration Transfer Function (VTF) and Acoustic Transfer Function (ATF). As the Trimmed-Body is an assembly of sub-systems, some of them developed in-house and other by external suppliers, FEM and TFs must be cascaded to all sub-system developers, including external suppliers. Confidentiality directives do not allow FE models sharing with external suppliers, precluding commodities development by suppliers to be driven by NVH attribute targets and requirements. Although the Global Static Stiffness is not a TF analysis, it is also considered part of NVH requirements. This paper shows how to obtain the static and dynamic reductions of the stiffness, damping, fluid-structure coupling, load and mass matrices of the Trimmed-Body FEM in order to generate a superelement representation with all design variables, as geometries, materials and properties hidden, with no reversal engineering possibility. It will allow external suppliers to develop their own sub-assemblies, considering NVH attribute targets and requirements. It is also part of this paper to propose the inclusion of superelements use on the engineering statement of work (SOW) in order to integrate the suppliers to all phases of new vehicle programs. |
Restoring and Upgrading of a Ford Motor Company Reverberation Room Test Suite | This paper presents the upgrades and improvements needed to bring an old and seldom used reverberation room test suite up to current standards. The upgrades and improvements included eliminating a below-floor pit that was open to the reverberation room, improving the acoustical diffusion within the room, enlarging the opening between the reverberation room and an adjacent anechoic chamber, renovating the anechoic receiving chamber, constructing an innovative sound transmission loss test fixture, and installing of a high power reverberation room sound system. |
Evolution of Trim Modeling with PEM for Structureborne Noise Prediction in Full Vehicle | The need in the automotive industry to understand the physical behavior of trims used in a vehicle is high. The PEM (poro-elastic method) was developed to permit an explicit representation of the trims in the FEM full vehicle models and to give tools to diagnose the effect of the trims and test design changes (porous material property, geometry, etc.,). During the last decade, the evolution of software and hardware has allowed the creation of models with highly detailed trim description (porous material using Biot parameters, plastic trims, etc.,). These models can provide good correlation up to 400Hz compared to measurements in contrast to classical NSM (Non Structural Mass) methodology which shows limitations. This paper will first introduce the classical method using non-structural masses, local masses and high values of acoustic damping to represent the trim which shows limitations for predicting the response above 200Hz and does not allow a detailed analysis of the effect of trims on the vibro-acoustic behavior of the vehicle. A review of the literature of the evolution of the modeling techniques for full vehicles with PEM representation of the trims is presented from early models with only some porous trims represented as PEM to the latest ones where most of the trim parts ranging from acoustic porous trim (dash insulator, absorbers, etc.,) to the elastic plastic parts (dashboard, pillar trims, etc.,) are included in the model. The influence of modeling accurately the coupling conditions between the trims and the inner cavity or the structure will be discussed. The different results available to diagnose the problems and the influence of the design improvements and visualize them via methods such as intensity contour plots will be introduced. |
Non-Linear Dynamic Analysis of a SuperPlug™ Door Module Response to a Door Slam Event | The SuperPlug™ door module is a new Delphi innovation. It is a one-piece composite structure, which integrates several door components into one assembly. This reduces the total part count, simplifies the vehicle level assembly process, and reduces labor cost (see the Appendix). The door slam durability test is an important factor in door module design. As more hardware is integrated into the SuperPlug, this subsystem performance in a door slam test becomes important. Therefore, the correct placement of components and the supporting structure is critical. Currently, the evaluation of door slam durability for the SuperPlug is a process of build then test. This is time consuming and costly due to a long testing lead-time and the expense of tooling a new mold. It was realized that a numerical process for assessing the effect of door slam would be required. This process would compute the dynamic response using finite element analysis (FEA). The first attempt within the Doors Systems group to simulate door slam used static FEA [1]. It was based on the assumption that the maximum dynamic loads could be modeled as point forces at the center of gravity of each component. This approach had the advantage of producing results quickly. However, the results are not considered realistic because factors like inertia, time and contact were not included in the analysis. It was then recommended to apply dynamic FEA methods that can consider these factors. This paper is a summary of a master’s degree thesis work on door slam [1]. It will describe how dynamic FEA was used to determine the response of a SuperPlug to a door slam. Discussion on how the FEA results compare with door slam tests will be presented. |
Autoliv’s Sound and Vibration Laboratory for Automotive Safety Component Development | The new sound and vibration laboratory at Autoliv’s Ogden Technical Center (OTC) was purpose-built with a focus on automotive safety restraint product development (air bags, seat belts, steering wheels, etc.). The laboratory requirements stem from the continued industry trend of quieter vehicles which drives the need for components with extremely low levels of rattle noise. The laboratory at OTC complements similar Autoliv testing facilities around the world. Test articles range from several cubic inches up to approximately one cubic foot and contain varying degrees of moving elements. With the new laboratory at OTC, Autoliv can test new product designs earlier in the development process and obtain test results and feedback faster. The function of the OTC test lab is vibration-induced rattle noise; shake components with a known input and measure the resulting noise. To provide an acceptable signal to noise ratio, the new laboratory was designed to have a 25 dBA re 20 μPa noise floor, reasonable Transmission Loss though the various partitions, modest internal reverberation control, and an ultra-quiet electrodynamic shaker. Achieving these goals required a site acoustic and vibration survey during the project planning phase, the results of which were compared to the performance criteria to drive the various architectural decisions. The resulting facility is capable of generating, recording, and analyzing the target sounds without concern for noise contamination. With this high quality vibro-acoustic information, design decisions can be made early in the product design cycle. |
The Noise and Vibration Response of Eight Light Vehicles on Sinusoidal and Conventional Rumble Strips | Noise and vibration measurements were conducted on eight light vehicles ranging from small compact passenger cars to a large sport utility vehicle on and off shoulder rumble strips of two different designs to assess the input to a vehicle operator when the vehicle departed from the travel lane. The first design was a more conventional design, consisting of cylindrical indentions ground into the pavement at regular 30 cm intervals, and a continuous sinusoidal profile with a peak-to-peak length of 36 cm. Triaxial vibration measurements were made at six locations, including the steering wheel and column, the seat cushion and track, and the front and rear spindles. Interior noise was measured at six locations, one at the operator’s outward ear and five at the front seat passenger (three in the fore/aft locations of the seat and at outboard and inboard ear locations). In addition to the in/on vehicle measurements, pass-by noise levels were made. The measurements were performed at 97 km/h and 72 km/h. The primary purpose of the measurements was to develop a recommendation for a standard rumble strip evaluation procedure that could be implemented by transportation agencies to assure comparable results when considering rumble strip designs that produce minimal exterior noise while maintaining sufficient warning input to the vehicle operator. This research did reveal some markedly different results between the test vehicles in both interior noise and vibration as well as pass-by noise. In this paper, these results are presented, and initial draft test procedures are reviewed. |
Practical Uses for Road Noise Cancellation | Today’s automotive customers have come to expect luxury and electric vehicles to be quiet and refined pieces of machinery. As customers have come to expect powertrain cancellation in most vehicles today, they are also increasingly looking for a reduction in road noise to improve their overall perception of luxury and electric vehicles. While the field of noise cancellation is ever expanding, several auto makers are exploring the possibility of introducing a real time Road Noise Cancellation (RNC) system to meet these customer expectations. An RNC system can be integrated into the vehicle infotainment system and be utilized to either noticeably reduce or shape the vehicle noise floor. This paper will look at the current traditional Noise and Vibration (N&V) methods of reducing road noise and then also the benefits associated with actively controlling the amount of road noise using an RNC system. |
Human Resources Integration Master Plan: A Response to Revolving Door Management | Taylor (1999) reported the effects of national cultures on the work values of aviation mechanics and Patankar (1999) reported the effects of their professional and organizational cultures. Taylor and Patankar (1999) found effects of national and professional cultures on the outcomes of maintenance human factors programs. Considering those effects, this paper focuses on a strategy that would encourage the champions of human factors programs to develop a human resources master plan and integrate it with the organizational culture. |
Structural Modules with Improved Crash Performance Using Thermoplastic Composites | A new group of composite materials “Advanced GMT” which are used for the economic production of light weight complex shaped parts in the automotive industry are presented. Advanced GMT consist of a combination of different technical textiles such as woven or stitched fabrics and non-woven mats which are impregnated with a polypropylene resin to a laminate. The laminate is flow molded to complex shaped components with a total cycle time of 30 to 60 seconds using standard equipment. The use of advanced GMT for weight saving and performance improvement of structural modules is discussed. Examples of such modules include hatchback or side door modules, front-end modules, bumper beams with integrated energy absorbers (crash cones) or spare wheel wells and structural elements in the power train. Common for all these type of modules or components is the need for geometric freedom in the design, crash worthiness including high specific energy absorption and ductile failure behavior, structural stiffness and economic production of large series. A case study of a side door module is presented. Aspects of the functional integration is shown with the complex features of the part allowing mounting of several elements such as side window railings, the lock, speakers etc. The versatility of advanced GMT is shown by a comparison in the crash behavior of the door module. The addition of local reinforcement of advanced GMT to a GMT structure increased the crash energy absorption with 300%, without weight increase. |
A Discussion On Using A Pendulum as a Method for Impact Testing Vehicle Sub-Systems | The purpose of this paper is to discuss the use of a pendulum as a repeatable method for impact testing vehicle subsystems and components. Tests on three different vehicle subsystems are presented as examples of impact testing that has been performed using a pendulum. Impact testing on two different roll bar designs to compare effectiveness, impact testing on various van side cargo doors to compare door latch integrity, and impact testing on various fuel tanks to compare the integrity of the fuel tank with and without shields installed. These tests were not intended to replicate the forces, energy, or impact pulse on the vehicle in the actual collision but rather evaluate how the vehicle subsystem reacted to impacts that were similar to that which occurred in the collision. Using proper instrumentation, it can be used to determine the forces or energy required to cause a localized failure or event, determine if an engineered solution has corrected the problem, and used to compare one design to another. |
Material and Design Innovation Techniques for Expanded Polypropylene (EPP) Products Used in Automotive Interior Applications | The use of Expanded Polyolefin foams including Expanded Polypropylene (EPP) material for interior applications has grown over the years to include applications throughout the vehicle. The demand for weight and cost reduction has forced designers to seek out the most versatile material available to satisfy the need for performance, durability, as well as design flexibility. The role of light-weight materials such as EPP has expanded. As such, the design challenges have also enabled the use of EPP in applications requiring energy management, as well as structural, acoustic, and storage/stowage functions. This paper will review the design guidelines that enable EPP to be used in numerous automotive interior applications. As EPP foam becomes more widely specified, and as the applications become more multifunctional, it is important to understand the potential solutions available to satisfy all aspects of design, performance, quality, and safety. Recent material developments and innovations allow for EPP to be specified in a wide range of densities, and with a variety of surface finishes and textures, as well as surface properties that allow it to be used in applications subject to NVH (Noise, Vibration and Harshness) requirements, and those requiring material compatibility. Technical innovations now allow for material optimization, which enable EPP to conform to the stringent performance requirements and BSR (Buzz, Squeak and Rattle) guidelines for today's automotive interiors. Performance can be affected using either mechanical or chemical solutions to satisfy OEM requirements. This paper will also highlight current production examples of EPP applications and their latest design and performance characteristics. Examples of recent performance studies will be cited; including graining and textured surfaces, acoustic enhancements, low friction solutions, and molded part operational and attachment methods. |
Advanced Source Localization Techniques Using Microphone Arrays | Microphone arrays used in vehicle acoustics are mainly designed for fast setup and basic evaluation (e.g. using delay-and-sum beamforming) resulting in a restriction to free field environments. Applications in vehicle interiors require advanced source localization techniques taking into account the reflections at the different panels appearing as mirror sources. Coherence filtering techniques allow for the detection of these mirror sources. An additional sensor is placed as a reference close to the main source. This reference signal is used to filter the array signals increasing the overall dynamic range of the acoustic source mapping. The discrimination of the original source and the reflections is obtained by manipulating the impulse responses between the reference signal and all microphone signals. Other advanced signal processing techniques can be used to increase the limited dynamic range of conventional beamforming such as principal component analysis removing the dominant sources. An implementation allowing for online application based on spatial filters will be presented. In addition the production requirements of large scale arrays, for example wind tunnel measurements and pass-by or fly-over measurements, are discussed. Manufacturing a large scale array with an appropriate precision for the microphone positions and the video system would be very expensive. A very efficient solution turns out to be a combination of a small calibrated camera module (consisting of a video system plus a small number of microphones with high-precision positioning) and a large scale array containing microphones with low-precision positioning. Array measurements using a standard loudspeaker for excitation serve as input for nonlinear optimization techniques to identify the positions of all microphones based on the orientation of the camera module. The techniques also allow for combining small arrays to increase the spatial resolution. This paper describes the theoretical background of different source localization techniques based on microphone arrays. Application examples are used to illustrate not only their advantages but also their potential drawbacks. |
Evaluation of Ground Vehicle Wind Noise Transmission through Glasses Using Statistical Energy Analysis | The contribution of wind noise through the glasses into the vehicle cabin is a large source of customer concern. The wind noise sources generated by turbulent flow incident on the vehicle surfaces and the transmission mechanisms by which the noise is transmitted to the interior of the vehicle are complex and difficult to predict using conventional analysis techniques including Computational Fluid Dynamics (CFD) and acoustic analyses are complicated by the large differences between turbulent pressures and acoustic pressures. Testing in dedicated acoustic wind tunnel (AWT) facilities is often performed to evaluate the contribution of wind noise to the vehicle interior noise in the absence of any other noise sources. However, this testing is time-consuming and expensive and test hardware for the vehicle being developed is often not yet available at early stages of vehicle design. In addition, modifications of the vehicle exterior geometry that may be beneficial to interior noise are often difficult to implement during the testing or to evaluate properly via test. This paper describes a test-based approach to measuring and understanding the contribution of exterior wind noise to the interior cabin noise through the individual glasses and the development of a correlated Statistical Energy Analysis (SEA) model capable of predicting the effect of a design change to any combination of thickness or material changes to the glasses. AWT testing was performed with interior microphones, accelerometers on the glasses, and arrays of flat exterior pressure transducers to establish the acoustic and structural-acoustic transfer functions to the interior. An underbody skirt, extensive taping of exterior gaps, and “blocker” parts on the interior of the glasses were used in order to isolate the noise contribution through individual glasses. Two versions of the front side glass -monolithic and laminated - were tested to compare the effect of the glass material and damping on transmitted wind noise and to provide a reference from which the wind noise load at this important location could be inferred. The data set from this testing was processed and used to correlate an SEA model of the test vehicle capable of being used for design studies of the effect of the glasses on the interior wind noise. |
Progress in Aeroacoustic and Climatic Wind Tunnels for Automotive Wind Noise and Acoustic Testing | There has been significant progress in developing test facilities for automotive wind noise and automotive components since the early 1990s. The test technology is critical to the development of modern vehicles, and essentially every major automotive manufacturer owns and operates their own aeroacoustic wind tunnel, or has rental access to one and conducts a significant amount of wind noise testing. The current status for climatic wind tunnels is that many new CWTs are being defined with acoustic test requirements. These test capabilities in AAWTs and CWTs will continue to enable the development of vehicles with better wind noise attributes, fewer problems with sunroof ‘booming’, and lower noise levels for HVAC and auxiliary systems. In the future, it is expected that the test demand for AAWTs and CWTs with low acoustic background noise will continue to increase as customers expect better automotive products, especially across more of the product line. The objective of this work is to present some of the progress and challenges involved in designing wind tunnels with low background noise in order to meet the requirements of automotive companies for their product development needs. |
Miga Aero Actuator and 2D Machined Mechanical Binary Latch | Shape memory alloy (SMA) actuators provide the highest force-to-weight ratio of any known actuator. They can be designed for a wide variety of form factors from flat, thin packages, to formmatching packages for existing actuators. SMA actuators can be operated many thousands of times, so that ground testing is possible. Actuation speed can be accurately controlled from milliseconds to position and hold, and even electronic velocity-profile control is possible. SMA actuators provide a high degree of operational flexibility, and are truly smart actuators capable of being accurately controlled by onboard microprocessors across a wide range of voltages. |
Automotive Engineering: January/February 2021 | Gearing EVs for greater efficiency Ingear, an innovative 2-speed transmission born in Canada, aims to unlock electric-vehicle performance and efficiency. Built-in Google vehicle apps arrive Android Automotive OS opens the door, cautiously, for third-party developers. Riding on air: Activated carbon aims at autos An old piece of science is set to bring new applications across the mobility spectrum. Allison builds a testing powerhouse Allison Transmission's new Vehicle Environmental Test center in Indianapolis is open for business for external and in-house customers alike. The VET has everything vehicle development teams need to improve testing efficiencies. Editorial The EVs are coming. Now what? SAE Standards News SAE J3178 Information Report for battery adhesives, sealants available Supplier Eye On my 2021 radar What We're Driving CES 2021: GM creates BrightDrop electrified delivery and logistics company Magna execs warn of impending EV complexities Hyperscreen brings new meaning to 'widescreen' display Dana's twin-clutch axle boosts Ford Bronco Sport's off-road cred Sparkling RWD platform underpins Genesis GV80 Nissan's 2021 Rogue is a COVID beater |
Noise, Vibration and Harshness of Electric and Hybrid Vehicles | The noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is a critical feature for customers to assess the performance and quality of vehicles. NVH characteristics are higher among factors that customers use to judge the vehicle's quality.This book sets out to introduce the basic concepts, principles, and applications of the NVH development and refi nement of Battery Electric Vehicles (BEV), Hybrid Electric Vehicles (HEV), and Fuel Cell Electric Vehicles. Each type comes with its own set of challenges. |
Passive Noise Reduction Possibilities for Trucks | Passive noise reduction decreases the transmission of noise and vibrational energy without altering or changing the noise generating components and mechanisms. The lessening of the transmission of noise and vibrational energy is achieved through the use of noise control materials and parts which provide vibration damping, insulation, or sound absorption. Noise sources radiate sound power and vibrate. The airborne noise propagates to the exterior and causes a particular maximum “A” weighted level to be measured during pass-by tests. Exterior or pass-by noise, and interior or in-cab noise are the two major noise problems for trucks. The major tasks of soundproofing a truck include the definition of treatments for exterior and interior noise and the choice and application of damping insulation and absorption materials in the cabin and engine compartment. |
The Building and Test-Track Evaluation of an Aluminum Structured Bertone X1/9 Replica Vehicle | A vehicle build and evaluation program to demonstrate the feasibility of Alcan's Aluminum Structured Vehicle Technology (ASVT) is described. Five replica Bertone Xl/9 sports cars have been built on the production manufacturing facilities of Carrozzeria Bertone in Turin. The all-aluminum alloy body structures were produced with strength and stiffness equivalent to production steel bodies but with a weight reduction of approximately one third. Modes and frequencies of vibration, interior noise characteristics and 30 mph barrier test results for vehicles with aluminum and steel bodies are compared. High load input, 1000 mile pave and accelerated corrosion tests have proved the vehicles' durability. |
Analysis of the Sound Field in an Automobile Cabin by using the Boundary Element Method | A method of analyzing the three-dimensional sound field in a full-size automobile cabin was studied. The acoustic resonant frequency and the acoustic mode of the cabin were calculated by using the boundary element method (BEM), and were then compared with an experiment conducted on a full-size cabin model made of plaster. The calculated resonant frequencies agreed with measured ones to within about 3% below 170 Hz, and the calculated modes and frequency response curves were in good agreement with experiments when the cabin wall was rigid. In the case of a wall partially lined with absorbing materials, the calculated resonant frequency and the damping ratio were approximately the same as the experimental ones. From these studies, it is concluded that the BEM is useful for analyzing the sound field in a full-size automobile cabin. |
Insulating Glazing in Side Windows | The main problem with the car climate while running is thermal asymmetry on the human body. This asymmetry is caused by solar radiation, drafts from cold air and drafts due to radiation from cold surfaces. During winter, the cold surfaces of the side windows are a major source of discomfort, not only because of the above-mentioned cold radiation towards the outer upper body parts, but also as a result of the air stream needed for demisting the windows. This air stream has a very low temperature when reaching the B-pillar, where it easily deflects, hitting the driver's/passenger's shoulder. In order to avoid these problems, tests have been carried out with side-lights consisting of two hermetically sealed panes with a small air space in between. It was found that the surface temperature is significantly raised, by some 15°C, at low ambient temperatures. Not only are the heat losses reduced, but mist formation is also prevented. Negative aspects are weight and cost. For future development, chemically tempered glass might create possibilities for lighter solutions. |
Environmental Influence on the Acoustic Performance of OEM Automotive Loudspeakers | Automotive audio systems and loudspeakers are typically designed, evaluated, and optimized, for best acoustical performance under indoor laboratory testing conditions. Review of the current loudspeaker engineering test standards, including those published by the car manufacturers, confirms this. Environmental testing is limited primarily to accelerated life tests which are subjective in analysis and often destructive. Although there are some post environmental test requirements for irreversible changes to acoustical performance, there are no requirements on how much the acoustical performance of loudspeakers may change while exposed to either high humidity or non - temperate temperature conditions. The effect of humidity and water on the acoustical performance of today's “waterproof” automotive loudspeakers is shown to be potentially audible. Recommendations are made for designing more environmentally robust automotive loudspeakers. |
Time Delay Imaging for Automotive Sound Systems | Delayed arrivals of a stereo source are manipulated to suppress undesirable vehicle cabin acoustics and replace them with optimum acoustics for reproduction of commercial recordings. These optimum playback acoustics are derived from concert hall and listening room measurements. An experimental vehicle sound system implementing these concepts is described. |
Towards an Objective Estimate of the Subjective Reaction to Diesel Engine Noise | A microcomputer-based analyser is being developed to estimate subjective reaction to noise from diesel-powered road vehicles. An interactive technique is envolving to match certain combinations of objective measurements to the subjective preferences of individuals, using a control signal from the microcomputer. For a pilot experiment on diesel engine noise at cold idle conditions, the sound stimuli were obtained from engine surface vibration signals. The pilot experiment results suggest that the impulsive characteristic of the sound could be more important than the overall level. |
Applications of Shape Memory Alloys in the Transportation Industry | Shape memory alloys (SMAs) - which have the ability to change from a “deformed” state to an original “remembered” state when triggered thermally - offer engineering properties available in no other material. Their potential has not been fully exploited. Existing applications for SMAs in the transportation industry include electric fog lamp louvers and a device to reduce rattling noise in manual transmissions. Future applications in the transportation industry include the use of high density, zero insertion force electric connectors, which are capable of withstanding extreme shock and vibration. |
New Concepts for Acoustic Material Selection | Significant developments in moldable noise reduction materials will allow design engineers of off-highway equipment to incorporate molded parts concepts into their design schemes for both the cab and engine compartments as their use of contoured shapes continues to increase. When properly designed, and used in conjunction with complementary treatments which have been carefully selected on the basis of proven acoustic test criteria, molded sound barriers and sound absorption parts are more cost effective than the oft seen overkill of conventional materials. |
Aerodynamic Characteristics of Subaru XT | In recent years much more attention is being paid to aerodynamics, resulting in vehicles that are far more highly refined aerodynamically emerging one after another. SUBARU's belief is that aerodynamic design of such vehicles should be well balanced with engine cooling, aerodynamic noise, field of view, dirt splash and other aspects and should not impair roominess, driving comfort, safety, and other requirements while properly controlling aerodynamic force. At SUBARU, vehicle aerodynamic design usually takes the following steps. First, 1/5-scale models are built and the aerodynamic characteristics of the actual vehicle are evaluated mainly based on such models. This is followed by building full-scale models with which equipment, underfloor, and other details are subjected to further evaluation, and thus development is promoted. |
Experimental Research on Vibratory Properties of an Engine Hood | A method and measurement system are developed for the experimental determination of vibratory properties of complex structures and applied to the determination of the engine hood for the passenger car “ZASTAVA”. Using a mechanical transfer impedance, the vibratory properties and damping factors are determined. The driving force at one point and the velocities at different points of the engine hood are measured. The vibratory properties of the engine hood have been analyzed and compared with regard to the stages of production completion: (1) engine hood without reinforcements, paint, and anti-rumble material; (2) engine hood without paint and anti-rumble material; and (3) engine hood complete. In all cases the engine hood was mounted on the nude car body for testing. Three levels of constant sinusoidal vibration force were applied in the middle point of the engine hood. The results are given in the form of velocity-frequency curves (velocity spectrum) for different measured points, force levels and different assembly stages in production. The hood reinforcements resulted in decreased output velocity levels of a factor between 2.0 and 2.5. On the other hand, the increase of the stiffness of the engine hood structure shifts the resonance frequencies and extends the peak outputs toward lower frequencies. A method for determination of the damping factor and relative damping are presented. By applying the anti-rumble material noise levels decreased by 1.0 to 1.5 dB(A). The output vibration levels decreased as well. |
Acoustic Analysis of a Light Truck Cab | Acoustic analysis of a Light Truck cab in the frequency range of 0 to 140 Hz was performed by utilizing an analytical method combined with experimental data. The structural and acoustic modes of the cab were determined by utilizing the MSC/NASTRAN dynamic analysis capability. Chassis, powertrain, and suspension components were simulated with the experimental modal data, acquired from dynamic testing of an actual vehicle. Triaxial transfer functions were obtained at all six cab-mount locations due to shaker excitation at the pinion nose and the 4 spindles, as well as neutral engine run-ups. The overall system model was constructed by combining analytical structural and acoustic modes with the experimental modal data using the modal synthesis technique and an in-house developed computer code called MOTRAN. The acoustic mode shapes, response at critical cab-structure locations, and interior sound level at the driver's ear were obtained. After the validity of the model was shown, the model was used to improve the acoustic response of the cab structure in terms of noise-related problems such as boom and drone. A new post processing method was developed to identify and determine the effects of "panel deadening" on the acoustic response of the vehicle. After extensive analytical iterations, an effective set of structural improvements were determined, and the recommended design modifications implemented on the vehicle. Subjective and objective evaluations were conducted to verify that the noise characteristics of the cab structure were indeed improved with the proposed design change. |
Effect of Glass Angles on the Cooling Loads of Automobile Air Conditioners | The characteristics of the directional total transmissivity of solar insolation through the glass panels of windshield, backlight and windows of automobiles are presented. The effect of the glass angles on the interior air temperature of the automobiles and the cooling loads of their air conditioners are discussed. |