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An Evaluation of Laminated Side Window Glass Performance During Rollover | In this study, the occupant containment characteristics of automotive laminated safety glass in side window applications was evaluated through two full-scale, full-vehicle dolly rollover crash tests. The dolly rollover crash tests were performed on sport utility vehicles equipped with heat-strengthened laminated safety glass in the side windows in order to: (1) evaluate the capacity of laminated side window safety glass to contain unrestrained occupants during rollover, (2) analyze the kinematics associated with unrestrained occupants during glazing interaction and ejection, and (3) to identify laminated side window safety glass failure modes. Dolly rollovers were performed on a 1998 Ford Expedition and a 2004 Volvo XC90 at a nominal speed of 43 mph, with unbelted Hybrid II Anthropomorphic Test Devices (ATDs) positioned in the outboard seating positions. Vehicle dynamics, occupant kinematics, and glazing failure modes were evaluated through: on-board instrumentation, analysis of on-board and off-board high speed video and film, a survey of the evidence in the rollover debris field, and post-test inspection of the vehicle, ATDs, and glazing. Laminated side window safety glass did not prevent complete ejection of the ATDs. Five of the six ATDs in the Expedition were completely ejected from the vehicle, and 3 of the 4 ATDs were fully ejected in the XC90 test. Containment of the two ATDs that were not completely ejected was unrelated to glazing contact; the laminated window adjacent to each ATD vacated the window opening and both were partially ejected during the roll sequence. Side window glass fracture and failure was observed in association with ATD loading, ground contact deformation, and combinations thereof. On the basis of the performance observed in this study, it is concluded that heat-strengthened trilaminate glass is not a suitable candidate for occupant containment during rollover. Comparison of these full-scale rollover tests to prior laboratory-based evaluations of laminated side glass demonstrates that the prior studies fail to account for several aspects of the rollover environment, which contribute significantly to glazing loading, fracture, and failure. |
CFD-based Modelling of Flow Conditions Capable of Inducing Hood Flutter | This paper presents a methodology for simulating Fluid Structure Interaction (FSI) for a typical vehicle bonnet (hood) under a range of onset flow conditions. The hood was chosen for this study, as it is one of the panels most prone to vibration; particularly given the trend to make vehicle panels lighter. Among the worst-case scenarios for inducing vibration is a panel being subjected to turbulent flow from vehicle wakes, and the sudden peak loads caused by emerging from a vehicle wake. This last case is typical of a passing manoeuvre, with the vehicle suddenly transitioning from being immersed in the wake of the leading vehicle, to being fully exposed to the free-stream flow. The transient flowfield was simulated for a range of onset flow conditions that could potentially be experienced on the open road, which may cause substantial vibration of susceptible vehicle panels. As these conditions cannot generally be replicated in the wind tunnel, a comprehensive numerical simulation methodology is required if this issue is to be addressed before vehicle prototypes are built. Transient aerodynamic simulations were performed using a Lattice-Boltzmann Method (LBM) and several different approaches were used to create dynamic onset flow conditions approaching the vehicle, such as simulating a: instantaneous transition to a twenty-degree yaw crosswind; twenty-degree harmonic yaw at 10 Hz; flow behind a ‘bluff body’ turbulence generating grid; ‘passing disturbance’; vehicle in the wake of another vehicle, at a range of separation distances. A structural solver was used to predict the amplitude of vibration of the hood under these flow conditions. The amplitude response was largest when the frequency content of the oncoming flow matched the natural frequencies of the hood; the turbulence grid was found to produce the largest vibration for this reason. This study shows that transient aerodynamics simulation coupled with a structural solver can be used to predict the onset of vibration for different flow conditions, which could be encountered on the road but cannot be easily reproduced in the wind tunnel. |
Validation of Interior Noise Prediction Obtained using Statistical Energy Analysis and Fast Multipole BEM | Statistical Energy Analysis (SEA) is an effective tool for evaluating the acoustic performance of a vehicle structure and sound package. SEA is typically used to predict both interior noise levels and to set noise reduction targets for various components. A typical full vehicle SEA model includes acoustic loads from airborne sources such as engine, tire and exhaust noise [1]. Each source is typically spatially compact (for example, a tire contact patch) but the source radiates sound that then propagates across the entire exterior surface of the vehicle. In order to characterize a source it is therefore necessary to know both the sound pressure level in the vicinity of the source and also the way in which sound from the source diffracts around the vehicle. A companion paper has investigated the numerical prediction of the diffraction of acoustic sources around a vehicle using the Fast Multipole Boundary Element Method [2]. In this paper, the exterior loads predicted by the FMM BEM method are applied to a full vehicle SEA model and used to predict the interior noise within the vehicle. The results are compared with experimental measurements and good agreement is observed. Modeling guidelines and assumptions are presented and discussed. |
Development of Sound Source Search Technology for High Frequency Noise in Vehicle Interiors | Continuously variable transmission (CVT) and hybrid systems, which have metal belts and electrical units not found in conventional transmissions, are susceptible to extremely High Frequency belt and electromagnetic noise between 5 to 10 kHz. The evaluation and reduction of high frequency (HF) noise of 5 kHz and more is therefore a critical point for improving the quietness of vehicles installed with such systems. This article describes new sound source search technology capable of identifying sources of noise up to 15 kHz in the vehicle interior. Unlike conventional beamforming methods, this new system uses an improved microphone array provided with additional acoustic material. This article outlines the development of the system and its application to sound source identification of HF noise in a hybrid vehicle. |
Why Thermoplastic Door Hardware Systems Make Economic Sense Now | Engineering thermoplastics are widely used in a variety of automotive components systems because of their excellent balance of mechanical performance, design flexibility, aesthetics, parts integration, and low specific gravity. This combination of properties allows for the creation of highly integrated modules, which can increase assembly efficiency and reduce mass, part count, warranty and ergonomic issues, and systems costs. As a result, the use of engineering thermoplastic materials can enhance market competitiveness at a time of increased global competition. To evaluate the economic advantages of polymers in a specific vehicle system, a design for assembly (DFA) case study was conducted with the goal of determining the variable system cost case for a generic thermoplastic door module system vs. conventional-build door systems based on assembly savings gains. This paper will describe the study and show the results achieved. |
An Alternative Approach to Robust Design: A Vehicle Door Sealing System Example | Designing a high-quality door sealing system at low cost is an economic and technological engineering challenge. Robust design is a systematic and efficient technique to meet this challenge of design optimization for performance, quality, and cost. This technique, also called parameter design, focuses on making product and process designs insensitive (i.e. robust) to hard-to-control variations called noise factors. In this paper, we illustrate and apply the principles of robust design using a response model approach to a door sealing system design problem where vehicle interior sound is the primary response being studied. The Appendix contains a glossary of all italicized words for reference. |
Measurement of Transient Vibrational Power Flow in a Car Door Panel Using Intensity Technique | In a structure, the noise source does not always coincide with the origin of excitation. Vibrational energy is transmitted in the structure and noise is radiated from the surface. For noise and vibration control in beam or shell structures, it is important to clearly identify the excitation sources and vibrational energy transmission characteristics. In this paper, measurement of transient vibrational power flow in a car door excited by impact using the envelope vibration Intensity technique is described. Vibrational power flow caused by flexural vibration in the car door panel is measured with the three channel method. The vibrational power flow is expressed with vibration intensity vectors at each measuring point. Instantaneous distributions of measured vibration intensity vectors in the car door panel are shown in this paper. Temporal and spatial variations of the vibrational power flow are discussed. |
Use of FCRASH in a Door Openability Simulation | During frontal and rear end type collisions, very large forces will be imparted to the passenger compartment by the collapse of either front or rear structures. NCAP tests conducted by NHTSA involve, among other things, a door openability test after barrier impact. This means that the plastic/irreversible deformations of door openings should be kept to a minimum. Thus, the structural members constituting the door opening must operate during frontal and rear impact near the elastic limit of the material. Increasing the size of a structural member, provided the packaging considerations permit it, may prove to be counter productive, since it may lead to premature local buckling and possible collapse of the member. With the current trend towards lighter vehicles, recourse to heavier gages is also counterproductive and therefore a determination of an optimum compartment structure may require a number of design iterations. In this article, FEA is used to simulate front side door behavior. Ford guidelines require the side doors, hatches and lift gates to be designed to remain closed during 35 mph perpendicular front (fixed) barrier crash tests. These guidelines also require the side doors to be designed to be capable of being opened without tools after the impact. While earlier analytical techniques [2] to handle door openability were based on door aperture deformation computations, this work describes a technique that is based on more realistic approach which directly simulates the process of door openability itself, using a finite element simulation. Therefore, it enables the simulation of an actual door behavior during and after perpendicular fixed barrier impacts. |
Development of a Door Test Facility for Implementing the Door Component Test Methodology | This paper describes the development of an automated Door Test Facility for implementing the Door Component Test Methodology for side impact analysis. The automated targeting and loading of the door inner/trim panels with Side Impact Dummy (SID) ribcage, pelvis, and leg rams will greatly improve its test-to-test repeatability and expedite door/trim/armrest development/evaluation for verification with the dynamic side impact test of FMVSS 214 (Occupant Side Impact Protection). This test facility, which is capable of evaluating up to four (4) doors per day, provides a quick evaluation of door systems. The results generated from this test methodology provide accurate input data necessary for a MADYMO Side Impact Simulation Model. The test procedure and simulation results will be discussed. Other features and advantages of the automated Door Test Facility are: elimination of “cut and weld” of structural braces of the old process accommodation of passenger car and light truck doors through a wide range of SID rams “seating” adjustments synchronization of SID rams movement and loading rate “freezing” the forward movement of “bottomed-out” SID ram(s) to maintain constant force to prevent trim panel spring back automated retraction of SID rams upon test completion. |
Glazing Effects of Door or Deformations in Crashes, Part 2 | The non-uniformity of temper of 27 motor vehicle door windows as measured by the polarization method is presented, illustrated by two photographs of windows between crossed polarizers. The tempered glass fracture characteristics of 11 Geo Prism door windows are illustrated by two video frames of the windows after fracturing by door deformation slowly applied at bumper level. The speed of some moderate sized fragments was measured to exceed 60 km/h, due to strain relief rather than contact by an intruding object. Glazing history is briefly summarized, with our support of the NHTSA conclusion that more than 1300 lives per year could be saved cost effectively by replacing tempered glass by an “advanced glazing.” |
Pressure Fluctuations in a Flow-Excited Door Gap Cavity Model | The flow-induced pressure fluctuations in a door gap cavity model were investigated experimentally using a quiet wind tunnel facility. The cavity cross-section dimensions were typical of road vehicle door cavities, but the span was only 25 cm. One cavity wall included a primary bulb rubber seal. A microphone array was used to measure the cavity pressure field over a range of flow velocities and cavity configurations. It was found that the primary excitation mechanism was an “edge tone” phenomenon. Cavity resonance caused amplification around discrete frequencies, but did not cause the flow disturbances to lock-on. Possible fluid-elastic coupling related to the presence of a compliant wall was not significant. A linear spectral decomposition method was then used to characterize the cavity pressure in the frequency domain, as the product of a source spectral distribution function and an acoustic frequency response function. The method was used to assess the effects of modifying the cavity geometry, adding sound absorbing material, and blocking the cavity orifice. |
Experimental Development of a Unique Door Cavity Sound Absorber | Airborne sound traveling through vehicle doors was a significant source of unwanted noise entering the passenger compartment of Saturn vehicles. To reduce these sound pressure levels, several different noise controls were assessed using nonstandard acoustical tests. The noise controls tested include door trim absorbers, barrier watershields, and various noise controls applied in the door cavity. Only when the noise controls were applied in the door cavity were significant noise reductions seen. The final developed part for use in the door cavity further enhanced noise reduction by using a combination of sound absorption and sound transmission loss. |
High Strain-Rate Tensile Testing of Door Trim Materials | The objective of this study was to determine dynamic tensile characteristics of various door trim materials and to recommend a practical test methodology. In this study, Polypropylene (PP) and Acrilonitryl Butadiene Styrene (ABS) door trim materials were tested. Slow speed (quasi-static-0.021 mm/s) and high speed tests were conducted on a closed loop servo-hydraulic MTS system. The maximum stress of these materials increased from quasi-static to dynamic test conditions (as much as 100%). The dynamic stiffness of PP increased two times from quasi-static tests. No significant change in stiffness was observed for ABS during quasi-static and dynamic tests at different strain-rates. Quasi-static and medium strain-rate (10-20 mm/mm/s) tests may be adequate in providing data for characterizing the dynamic behavior of trim materials for CAE applications. Strain gages can be used to measure the quasi-static and in some cases, dynamic strain. Strain gage effect on material properties can be assessed by comparing the maximum stress from tests with and without strain gages. |
Sound Power Measurement in a Semi-Reverberant, Volume Deficient Chamber | Sound power can be determined using a variety of methods, but precision methods require the volume of the noise source to be less than 1% of the chamber volume leading to relatively large test chambers. Automotive torque converter performance and noise testing is completed in an enclosed metallic test fixture which inhibits the use of precision methods due to volume and space limitations. This paper describes a new method developed to accurately determine sound power of an automotive torque converter in a relatively small enclosure through characterization of the test environment. The test environment was characterized using two reference noise sources designed to represent torque converter noise output and physical geometry. Sound pressure levels of the sources were measured at multiple microphone locations and at three source amplitude levels to characterize the environment. Test results were analyzed statistically to determine the microphone positions that best represent the overall sound levels in the chamber. Optimum measurement positions were found to depend on source size but independent of source amplitude. Accuracy was determined based on the variance between the sound pressure levels at each microphone position. Sound power correction factors were found using sources of known sound power and the optimum microphone positions. The new method allows estimation of sound power of operational torque converters in a dynamometer test fixture. |
Acoustic Diagnostic Network Algorithms, their Description and Implementation from Concept into a Comprehensive Vehicle Optimization Program. | Acoustic Diagnostic Network Algorithms (DNA) are experimental methods that extract airborne acoustic characteristics from a motor vehicle and decompose this information into a set of networks from which the source, path and receiver noise sources and paths can be determined. Unlike traditional transfer path analysis Acoustic DNA takes the problem into the fine detail. It answers questions such as what, where and how does a vehicle's acoustic systems need to be changed in order to achieve any given objective. This paper describes the fundamental methodology and features together with how it has been implemented into a computer program that has been used successfully in over 50 vehicle projects within the Authors Research and Development group on a wide range of motor vehicles. |
Understanding the aeroacoustic noise mechanisms and noise control techniques of roof rack systems | Aeroacoustics is one of the top NVH concerns in the automotive industry. HEV/EV have increased the challenge in rebalancing wind noise, and SDC is pushing sound quality requirements to be significantly more demanding than they are in conventional ICE manually-driven vehicles. The most severe aeroacoustic phenomena in ground vehicles are the ones with a tonal nature. Roof rack systems are directly exposed to the airflow and generate broadband noise and a discrete aeolian tone. Typical crossbar profiles are variations over an elliptical profile, i.e. not as blunt as a circular cylinder, neither as thin as a wing section, and a particular solution optimized for one profile will prove less effective in different designs. Therefore, the objective of this project is to investigate the noise mechanisms involved in elliptical crossbars through actual acoustic measurements taken on track. The first part of the project correlated exterior acoustic pressure and intensity measurements taken on track and in an aeroacoustic wind tunnel with the objective of assessing accuracy and repeatability. Exterior sound pressure on-track has demonstrated good accuracy in capturing both narrow and broadband noise effects, despite the uncontrolled background noise. The crossbar wake interaction with the roof plane was investigated through local flow visualization and reference aeroacoustic measurements. The second part of the project compared the noise generated by an elliptical cylinder with that generated by a circular cylinder and a NACA 0012 airfoil with the same thicknesses and at the same operational conditions. Results have shown that the elliptical crossbar noise characteristics have similarities when compared to those of blunt bodies at low Reynolds numbers and wing sections at higher speeds. Different leading and trailing edge geometries demonstrated that the trailing edge is the key contributor to the aeolian tone, while the leading edge affects primarily the broadband noise. Noise control techniques such as Angle of Attack and two and three-dimensional Boundary Layer Tripping (BLT) were investigated. Positive and negative incidence angles presented opposite trends towards noise reduction and have proven to be ineffective at higher speeds. 2D and 3D BLT did not eliminate the main tone but reduced its amplitude and bandwidth. 3D BLT techniques have demonstrated an advantage over 2D BLT. Innovative solutions such as Perforation and active Trailing Edge Blowing (TEB) were assessed. Both Perforation and TEB were effective in reducing the aeolian tone but presented side effects such as high frequency whistling, thus requiring further geometric optimization. |
Instructions for New Projects and Validation Guidelines of Tonneau Covers for Pickup Truck Bed | The purpose of this paper is to suggest guidelines for new projects of soft tonneau covers for pickup truck beds made up of aluminum framework and soft coverage. As the main objective, this paper will make an overall about new accessories projects focusing on each one of the main components of the assembly. The target is to obtain a low cost tonneau cover with a great performance regarding functionality, water accumulation, sealing, noise, robustness, vibration and compatibility with another pick up box's accessories. This article also explores basic procedures for testing and validation of a new soft tonneau covers or a carry over one, with its use extended to a different pickup truck. It is one of the first technical documents about truck soft tonneau covers available, so few references could be found in technical databases. Into this scenario, this article had the objective of give an overall about the subject, offering basic information for new developments and being a start point for future and in-depth studies about this truck component. |
CAA Application to Automobile Wind Throb Prevention Design | When a window opens to provide the occupant with fresh air flow while driving, wind throb problems may develop along with it. This work focuses on an analytical approach to address the wind throb issue for passenger vehicles when a front window or sunroof is open. The first case of this paper pertains to the front window throb issue for the current Ford Escape. Early in a program stage, CAA (Computational Aeroacoustics) analysis predicted that the wind throb level exceeded the program wind throb target. When a prototype vehicle became available, the wind tunnel test confirmed the much earlier analytical result. In an attempt to resolve this issue, the efforts focused on a design proposal to implement a wind spoiler on the side mirror sail, with the spoiler dimension only 6 millimeters in height. This work showed that the full vehicle CAA analysis could capture the impact of this tiny geometry variation on the wind throb level inside the vehicle cabin. The independent wind tunnel effort came to the same conclusion, and the difference between the analysis and testing is only about 1 dB. With the implementation of this spoiler, the program target was finally met. The second case of this paper deals with the sunroof throb issue for an SUV. The work concentrates on the modeling method of wind deflectors made of meshed fabric material and carrying out CAA analysis to access the sunroof wind throb level. The result shows that CAA can predict very well the impact of the wind deflector made of meshed fabric material on the wind throb level, in line with the subjective evaluation on proving ground. In summary, this work manifests that CAA is a very effective tool for wind throb prevention design when hardware prototypes are not available. |
Custom Configuration of a Vehicle Electrical Control System for Production and Service | International Truck Engineering has incorporated a cab electrical system controller (ESC) into their vehicle design. This was done to facilitate a larger number of configurations with a simpler hardware design. The ESC makes use of SAE J1939 and J1708 to communicate with instrument cluster, door, power train and other modules. It also has various discrete inputs and outputs. A proprietary operating program written for the ESC uses a set of binary configuration structures stored in flash ROM and includes a proprietary “byte code” interpreter. The configuration describes how to process all I/O signals to/from a central data array, byte code to execute and the instrument cluster layout. Byte code operates on the data array between input and output processing. The switches and gauges in the instrument cluster plug into network modules. Due to the variability of the International Truck & Engine vehicle products, the content of the ESC configuration can vary widely from vehicle to vehicle. It is the IT (Information Technology) organization's task to provide a specific configuration for each ESC. Based on customer ordered features, the configuration must contain the proper byte code modules, I/O processing and cluster configuration information. IT must also select the proper switches, gauges and warning lights and their locations, as well as match the discrete I/O to signals on pre-existing wiring harnesses. The software and hardware included in the configuration must be validated to prevent software and hardware conflicts. In addition to the initial configuration, IT must also provide vehicle service support. This includes reconfiguration of the ESC for software updates, recall support and customer driven additions or modifications. The system that IT developed to solve these issues is discussed. |
Closed-Loop Recycling of Monomaterial Door-Panel Systems | Pressures to increase the recyclable and recycled content of passenger vehicles are accelerating. In Europe, there is interest in eliminating halogenated polymers. Globally, more and more concern is focused on materials and methods that are ecologically friendly. Automakers and their suppliers are being encouraged to design and assemble components in new ways to facilitate separation, identification, and resource recovery at the end of the vehicle’s useful life - something that is not only good for the environment, but also the bottom line. One area of the vehicle that has proved challenging for applying such design for disassembly and recycling (DFD/R) principles has been the interior, owing to the sheer number of materials used there, and the great number of laminate structures that make disassembly nearly impossible. A good example is a door panel inner, which typically consists of a rigid plastic substrate, a foam pad, and a vinyl, leather, or cloth covering. This component is usually comprised of different materials tied with adhesives and polyester scrim fabrics. Fortunately, recent material developments as well as process enhancements have now made it possible to quickly and efficiently manufacture all-olefin door panels without adhesives or scrim, making the monomaterial door panels excellent candidates for recycling. But how recyclable are these systems? A recent manufacturing study successfully recycled fully covered door-trim panels comprised of an olefin-based coverstock, a cross-linked olefin foam pad, and a polypropylene (PP) substrate. Processing scrap was chopped and reintroduced - at predetermined weight ratios - back into the virgin resin feedstream used to produce additional PP door substrates. A variety of tests were performed both on plaques and full door panels comprised of varying ratios of virgin + recycled material to see if the presence of the recycled material affected any physical or mechanical properties, processability, or other engineering specifications. The results of this testing program are presented here, along with recommendations for implementing a closed-loop recycling program. |
An Integrated Automobile Keyless Operation System | An integrated automobile keyless operation system is developed. The system consolidates the ignition key and lock/switch, security and keyless entry and other functions into one unit. The system uses a small handheld portable wireless remote controller to replace the ignition key, the door key and the trunk key. A receiver replaces the ignition switch and functions as controlling switches for door-locks and/or trunk-lock. The system incorporates the latest advancement in wireless technologies and digital-signal processing. By consolidating components, the design cuts manufacturing cost, improves reliability and offers outstanding convenience and enhanced security. |
Sensory Evaluation of Commercial Truck Interiors | Vehicle interior harmony is related to human factors but it deals with human emotional attachment to the product. Kansei, or sensory engineering provides an effective approach to address harmony issues. This paper reports a preliminary investigation of human sensory evaluation of commercial truck interiors, especially the door interiors. To investigate the end users' needs and preference, a questionnaire survey was administered to twenty-six commercial truck drivers. Responses on usability, styling, harmony, and ergonomics issues of each driver's own truck were recorded. Furthermore, a set of 12 semantic differential scales, together with a preference ranking scale, was served to evaluate six truck door interiors. Results show that commercial truck drivers are more concerned with functionality and usability than styling and visual harmony. However, concerns on interior styling and harmony represent more than one-third of the design issues reported by the participants, indicating that interior harmony issues should not be overlooked. Three factors of door interior visual harmony were identified: color and emotion, geometric shape, and spatial arrangement. The color and emotion factor showed a high correlation with preference ranking merit value. Future work will be carried out to associate principal harmony factors with design parameters of door interiors. |
Foresight Vehicle: Large Area Flexible Circuits for Automotive Applications Manufacturing Technology - A Review of Process Options | It is the intention of motor vehicle manufacturers to achieve weight and cost savings by replacing wiring harnesses with flexible printed circuits in doors, roof liners, boots and cockpits. These circuits will be required in high volume and must meet the requirements of the vehicle and equipment suppliers with respect to cost effectiveness and reliability while presenting an achievable, economically sound manufacturing technology to the circuit suppliers. Design issues include requirements for CAN-bus1, EMC/RFI protection, 42 volt systems and the integration of functional modules 2,3,4. Alternative construction options and criteria for their assessment are proposed. The range of processes from which a manufacturing technology can be established are identified and discussed. The challenges presented to available processes and equipment by the potentially very large circuits are examined. |
A Development Procedure to Improve the Acoustical Performance of a Dash System | This paper discusses a development procedure that was used to evaluate the acoustical performance of one type of dashpanel construction over another type for a given application. Two very different constructions of dashpanels, one made out of plain steel and one made out of laminated steel, were studied under a series of different test conditions to understand which one performs better, and then to evaluate how to improve the overall performance of the inferior dashpanel for a given application. The poorly performing dashpanel was extensively tested with dashmat and different passthroughs to understand the acoustic strength of different passthroughs, to understand how passthroughs affect the overall performance of the dash system, and subsequently to understand how the performance can be improved by improving one of the passthroughs. |
Massive Point Cloud Data Sets and Single Point Measurement Acquisition in the Production Floor Environment | In typical production lines of automotive manufacturers, body parts are produced every several minutes. Sample parts are measured at certain intervals with a CMM machine at approximately 30 points to verify correct production. The points measured on each sample part are compared with reference points of a golden part or with the CAD model. This paper presents results achieved with a high-accuracy non-contact 3D measurement system capable of measuring both the full surface of sample parts and surface points (surface point measurement, or SPM), after production, on the production floor. The technology used enables high-speed image acquisition of large data sets together with CMM-like capability of measuring individual points, both accomplished simultaneously. SPM measurement of a car door requires approximately 15 minutes; measurement of a full door surface, including SPM, requires less than 1 hour if operated manually, or alternatively 3 minutes for SPM and approximately 10 minutes for full surface measurement if performed by a robot-based system. The system is capable of measuring shiny, oily and/or dirty parts, which makes it suitable for measurement right on the production floor. The resulting surfaces and points measured are aligned to vehicle coordinates by the system, and compared to the CAD design. SPMs are compared to their reference points, and reports are exportable. Examples of series of COP/CAD comparisons will be presented, taken on the production floor, illustrating the gradual development of a production defect and its detection with the full surface data. Such defects can immediately be found, when measuring the entire surface of each part, during production (in process). Corrective action can be taken before inaccuracies get out of control. |
A Method to Determine the Power Input Associated with Rain Excitation for SEA Models | Statistical Energy Analysis is used to predict the sound pressure level (SPL) in the interior of the vehicle. This is accomplished by knowing the energy sources (tire, engine, wind, etc) affecting the interior as well as the acoustic performance (absorption and transmission loss) of the interior trim components (headliner, door panels, instrument panel, etc). One of the noise sources that has not been seriously examined to-date is panel excitation by precipitation. The excitation of the roof due to raindrops can be a major noise source. Knowing how to properly model this power input would help analyze different headliners or roof treatments to minimize the SPL in the interior cavity. This will involve computational determination of mass, speed, and energy of standard water droplets for one of rain condition. A power spectrum is presented for one rain intensity condition on a test fixture. |
E-Modularization of Rear Closures: Integration of New Generation of Electrical Systems | This paper presents the potential for rear closure submodules. Side door modules and lightweight rear closures have attracted a lot of attention in recent years. However the characteristics of future liftgates allow the design of specific mechatronic sub-modules (e-modulesTM). Beside structure, rear closures satisfy three main functions: rear vision, rear signaling and rear access. All are undergoing a generation change that will be outlined in the first part of this paper, system by system. Each time the rationale behind modular integration, whether electronic or mechanical, will be reviewed. The second part presents examples of e-modulesTM that illustrate the potential gains in terms of ease of assembly, packaging optimization and network integration. |
Development of Composite Body Panels for a Lightweight Vehicle | Recently weight reduction is increasingly needed in automotive industry to improve fuel efficiency and to meet a CO2 emission requirement. In this paper, we prepared composite body panels for the lightweight vehicle based on a small passenger car. Fender, roof, door, side outer panel, and tailgate are made from hand layup using a glass/carbon hybrid reinforcement. Hood is made from low pressure sheet molding compound (SMC) to investigate feasibility of mass production. Both hand layup and low pressure SMC materials are newly developed and their physical properties are examined. CAE simulation was done for strength analysis and optimization of thickness for the body panels. |
A New Wavelet Technique for Transient Sound Visualization and Application to Automotive Door Closing Events | Transient automotive sounds often possess a complex internal structure resulting from one or more impacts combined with mechanical and acoustic cavity resonances. This structure can be revealed by a new technique for obtaining translation-invariant scalograms from orthogonal discrete wavelet transforms. These scalograms are particularly well suited to the visualization of complex sound transients which span a wide dynamic range in time (ms to s) and frequency (∼100Hz to ∼10kHz). As examples, scalograms and spectrograms of door latch closing events from a variety of automotive platforms are discussed and compared in light of the subjective rankings of the sounds. |
Percentile Frequency Method for Evaluating Impulsive Sounds | The Percentile Frequency method originated in an attempt to quantify the frequency content of door slam sounds. The method is based on the Specific Loudness Patterns of Zwicker Loudness. Zwicker states that the area of the Specific Loudness Pattern is proportional to the total loudness. The method summarizes each Pattern as seven frequencies identifying the contributions of fixed percentages of the total area (i.e. 10%, 20%, 30%, 50%, 70%, 80% and 90%). Applying the method to each Pattern in a time series generates a family of curves representing the change in relative frequency content with time. The process, in effect, normalizes the frequency content of the impulse for loudness and reduces the data to a two dimensional plot. On a Percentile Frequency plot a simple impulse appears as a pattern of “nested, inverted check marks.” More complicated impulses, such as rattles, have more complicated shapes that are still “nested” together. Applying this understanding to practical problems, the method has been used to visually show the progress of a project to reduce rattles occurring in door slam sounds. The method also has been used to quantify the low pitched “thump” of a door slam sound. In addition, a further extension of the method has been successful in differentiating high pitched door latch closing sounds. By incorporating these techniques into a general door slam sound test, it should be possible to evaluate objectively for rattles, latch sound, and “thump” as well as loudness. |
Door System Design for Improved Closure Sound Quality | Door closing sounds are an important element of the craftsmanship image of a vehicle. This paper examines the relationship between closure sound quality and door system design. The perception of door closing sound quality is shown to be primarily related to it's loudness and sharpness. Of the two, sharpness is more important than loudness. Other factors, like ring-down may also affect closure sound quality. The door system is made up of a number of components. The most important in terms of sound quality are the door and body structure, latch, and door seals. Each of these are classified as either a sound source, a transmission path or a sound radiator. Methods for improving the design of these components for good closure sound quality are discussed in some detail. |
A Study on The Hybrid Finite Element Modeling for Side Impact Simulation | In this study we suggest simplified and design oriented hybrid modeling methodology to the development of crashworthy structure. This hybrid model consists of main structure, which are modeled by beam and springs and doors modeled by shells. The main structures such as B-pillar roof rail and side sill are represented by nonlinear springs which have the same section properties as shell model have. The localized collapse of main structures are represented by non-linear spring elements whose moment-rotation characteristic is calculated based on Wierzbicki’s equation. The joint parts are represented by non-linear springs, which have the same moment-rotation characteristics as those of real parts to hold actual collapse characteristics. To represent force transition between structure and door, anti-sliding shells are introduced in the area of side-sill and lower part of Bpillar. Using this hybrid modeling methodology, we can get a good correlated result for full model and reduce calculation times around 80% for full FE shell model. |
CFD Simulation of Side Glass Surface Noise Spectra for a Bluff SUV | Simulation of local flow structures in the A-pillar/side glass region of bluff SUV geometries, typical of Land Rover vehicles, presents a considerable challenge. Features such as relatively tight A-pillar radii and upright windscreens produce flows that are difficult to simulate. However, the usefulness of aerodynamics simulations in the early assessment of wind noise depends particularly on the local accuracy obtained in this region. This paper extends work previously published by the author(1) with additional data and analysis. An extended review of the relevant published literature is also provided. Then the degree to which a commercial Lattice-Boltzman solver (Exa PowerFLOW™) is currently able to capture both the local flow structure and surface pressure distribution (both time averaged and unsteady) is evaluated. Influential factors in the simulation are shown to be spatial resolution, turbulence and boundary layer modelling. It is demonstrated that, whilst reasonable predictions are obtained for the surface noise spectra, both the size and strength of the A-pillar vortex are substantially over-predicted. Finally an attempt is made to estimate the frequency range that the simulation could be reasonably expected to capture. This analysis suggests that the simulation is bounded by the limitations of the turbulence model, rather than spatial resolution. |
Low-Cost Audio for Automobiles | Much design effort is given to the development and tuning of high-end automotive audio systems. Typically, premium speakers, separate amplifiers and careful tunings are used to create very high audio performance levels. Lower cost vehicles and vehicles of lower trim levels often feature more ordinary speakers and no separate amplifier. This typically leaves a number of listeners with little option for enjoying adequate bass performance, improved stereo imaging, etc. Small changes in acoustical component features and specifications can produce significant returns in spectral performance. Additionally, low-cost, powerful audio digital signal processing (DSP) has made its way into modern receivers. As the processing power of these devices improves, there are new opportunities for lower-level vehicles to produce customer-pleasing levels of audio performance. This paper addresses issues facing designers of lower-end audio systems and proposes solutions for potentially vexing problems such as those caused by non-linear speaker excursion. Informal listening test results from expert and non-expert listeners are also included. |
Study and Application of Prediction Method for Low Frequency Road Noise | When a vehicle drives over road seams or a bumpy surface, low-frequency noise called drumming is generated, causing driver discomfort. The generation of drumming noise is closely related to the vibration characteristics of the suspension, body frame, and body panels, as well as the acoustic characteristics of the vehicle interior. It is therefore difficult to take measures to get rid of drumming after the basic vehicle construction has been finalized. Aiming to ensure drumming performance in the drawing review phase, we applied the Finite Element Method (FEM) to obtain acoustical transfer functions of the body, and Multi Body Simulation to get suspension load characteristics. This paper presents the results of the study of drumming prediction technology using this hybrid approach. The paper also describes the results of 1) analyzing actual driving behavior when drumming occurs using a multi-point simultaneous measuring system, 2) analyzing suspension vibration characteristics as a cause of drumming, and 3) validating the correlation between the FEM model and an actual vehicle using Robot-controlled 3D Scanning Laser Vibrometers. Modifications made to the actual body structure are also introduced as a case study on effective drumming reduction. |
An Iterative Approach Based on Prony's Method to Calculate the Surface Impedance of Acoustic Materials Measured in situ | In many cases the in situ measurement of the absorption coefficient requires an iterative method for the correct calculation of the surface impedance of a sample. This happens because when spherical waves reflect on a sample's surface the pressure field above it is a function of the sample's surface impedance. As the pressure field involves an integral term, numerical integration is required in the iterative algorithm, which can be time consuming. The aim of this paper is to present an iterative approach based on Pony's method, which instead of numerical integration uses a series expansion with a few terms. Therefore the time of processing is decreased. Besides the description of the method, simulations and measurements (with a p-u probe inside an office room and a car) are presented. A comparison, with numerical integration, regarding the accuracy and the time of processing of Pony's method is also discussed. |
Auditory Localization of Backup Alarms: The Effects of Alarm Mounting Location | Sound localization of a backup alarm is important in situations when vehicles are reversing. Previous work has demonstrated the effects of ambient noise level and the spectral content of the backup alarm on localization. In the current study, we investigate the effects of backup alarm mounting location on localization performance. To address this question, we asked blindfolded listeners to localize backup alarms installed in positions that provided either direct (e.g., installed on the outer rear aspect of the vehicle) or indirect (e.g., installed within the inner frame rails of the vehicle) sound propagation paths to the listener. Additionally, we explored the effects of ambient noise level and the direction of origin of the alarm (behind, in front of, or to the left or right of the listener), and the interactions among all three factors (alarm location, ambient noise, and alarm direction relative to the listener). Localization performance was examined in terms of percent correct localization, as well as percent front-back confusion errors. When the alarm stimuli were presented in front, the alarm that was mounted directly in front of the listener -- providing a direct path to the listener --produced more correct localizations than the other alarms. This direct-path alarm also resulted in the least front-back confusions overall. However, when the alarm stimuli were presented behind the listener, the alarm mounted at the top of the rear of the truck --providing a direct but elevated path to the listener -- produced the worst performance and the most front-back confusion errors. An important factor affecting listeners' localization performance was the orientation of the listener relative to the direction from which the alarm stimuli originated. When the alarm was to the right or left of the listener, all alarm mounting locations produced equally good performance and no front-back confusions. Alarms originating from behind the listener, however, generally produced the worst performance, and the most front-back confusions, for the majority of the alarm mounting locations. |
Efficient CFD Simulation Process for Aeroacoustic Driven Design | The transport industries face a continuing demand from customers and regulators to improve the acoustic performance of their products: reduce noise heard by passengers and passersby; avoid exciting structural modes. In both the aerospace and automotive areas, flow-induced noise makes a significant contribution, leading to the desire to understand and optimize it through the use of simulation. Historically, the need for time-consuming, computationally expensive transient simulations has limited the application of CFD in the field of acoustics. In this paper are described efficient simulation processes that, in some instances, remove the requirement for transient analyses, or significantly reduce the total process time through intelligent pre-processing. We will outline this process and provide both automotive and aerospace industrial examples, including analyses of highly complex geometries found in real life. Section 2 describes a modeling hierarchy which includes steady-state, transient and frequency-based time-periodic methodologies. Section 3 contains four popular classes of application spread across the transportation sectors: - Airframe noise simulation of a complex nose landing gear; - Aeroacoustics of avionic cooling rack in an Airbus cockpit; - Automotive sunroof buffeting with structural impedance; - Fan noise signature in the presence of gusts. For these case studies, the main focus is the prediction of aeroacoustic noise sources. The propagation of noise to the far-field is not considered here, though some qualifying comments are made in section 2.4. |
Optimization of Bus Body Based on Vehicle Interior Vibration | In order to solve the abnormal vibration of a light bus, order tracking analysis of finite element simulation and road test was made to identify the vibration source, finding that the rotation angular frequency of the wheels and the first two natural frequency of the body structure overlaps, resonance occurring which lead to increased vibration. To stagger the first two natural frequency and excitation frequency of the body, thickness of sheet metal and skeleton of the body-in-white were chosen as the design variables, rise of the first two natural frequency of the body-in-white as the optimization objective, optimal design and sensitivity analysis of the body-in-white was carried out with the modal analysis theory. Combining with the modal sensitivity and mass sensitivity of sheet metal and skeleton, the optimum design was achieved and tests analysis was conducted. Comparing the test results before and after optimization, the effectiveness and rationality of the optimization is verified. |
Assessment of a Vehicle's Transient Aerodynamic Response | A vehicle on the road encounters an unsteady flow due to turbulence in the natural wind, due to the unsteady wakes of other vehicles and as a result of traversing through the stationary wakes of roadside obstacles. There is increasing concern about potential differences between the steady flow conditions used for development and the transient conditions that occur on the road. This paper seeks to determine if measurements made under steady state conditions can be used to predict the aerodynamic behaviour of a vehicle on road in a gusty environment. The project has included measurements in two full size wind tunnels, including using the Pininfarina TGS, steady-state and transient inlet simulations in Exa Powerflow, and a campaign of testing on-road and on-track. The particular focus of this paper is on steady wind tunnel measurements and on-road tests, representing the most established development environment and the environment experienced by the customer, respectively. Measurements of the surface pressure on the front sideglass were used for comparisons as this area exhibits a complex flow which is highly sensitive to yaw angle and which is also an important region, for wind noise considerations in particular. It was found that, if the transient on-road environment is known then steady-state wind tunnel measurements can be used to predict accurately the transient surface pressures, provided the methodology is sufficiently rigorous. Admittance or transfer function techniques are commonly used to compare transient and steady-state results and the limitations of these methods are shown here when the spectra of self-excited and externally imposed unsteadiness overlap. A new method is introduced to obtain a “true” transfer or admittance function, unconfused by the presence of self-excited unsteadiness. The aerodynamic admittance was found to be close to unity up to a frequency of 2-10 Hz and it then drops progressively. |
A Comparative Study of Automotive Side Window Occupant Containment Characteristics for Tempered and Laminated Glass | This study investigates occupant containment characteristics of tempered and laminated automotive moveable side glass in rollover collisions. FMVSS 216 test protocols were used to induce roof damage or sheet metal damage around the window opening in Lincoln Navigators equipped with tempered and laminated side glass. Dummy-drop tests were then performed to investigate relative containment. The results demonstrate that, for rollovers in which the window structure is compromised, tempered side glass and laminated side glass perform comparably relative to occupant containment. Also discussed are the general strength characteristics of different types of glass construction, the availability of laminated side glass in recent model U.S. vehicles, and anecdotal data supporting the conclusions of testing. |
On the Use of the Fast Multipole Method for Accurate Automotive Body Panel Acoustic Load Predictions | Knowledge of the external sound field around a car body is critical for vehicle acoustic development. Airborne isolation predictions, and thus panel and trim design depend on this data. Nowadays, such information is the result of experimental methods, as previously investigated simulation solutions proved either too costly, or not precise enough. In this paper, we investigate the use of a method combining computational efficiency and results accuracy: the Fast Multipole Method. This boundary-integral method uses an iterative solver and does not require a full assembly and factorization of the system matrix, thus allowing precise calculations over an extended frequency range even for large objects. In the present study, we demonstrate the potential of the method on a mid-range van, the Renault Scenic. |
SEA Model Development Considerations for Cost-Driven or Developing Market Vehicles | In South America and other developing markets the NVH development of a vehicle is often limited by the cost of the sound package components. In an era where cost reduction is crucial not only in developing markets, but also in developed markets where any cost or weight savings is a large competitive advantage, lessons learned from considerations for NVH analysis for vehicle design in developing markets can be applied to vehicle NVH design everywhere. A Statistical Energy Analysis (SEA) model was used to target and identify the dominant paths in need of sound package modifications to decrease the over sound pressure levels and also to identify paths in which sound package (and cost) could be reduced or deleted with no discernable degradation to the overall interior levels. This model will be used to support or challenge ongoing proposed sound package modifications to the vehicle and serve as a baseline template for design phase work for other vehicles of a similar body style. |
Contribution Analysis of Vehicle Interior Noise Using Air-borne Noise Transfer Function | The efficient insulation of noise transmitted from the powertrain is one of the important issues in developing the variation or minor change of the vehicle. This paper deals with the contribution analysis of each path of interior noise by window mask method using air-borne noise transfer function and shows the application of Taguchi method in finding the best combination of the insulation countermeasures. To this aim, the vehicle interior cabin is segmented into 25 windows and the air-borne noise transfer functions between source and receiver points are measured by acoustic reciprocal method. |
Investigation of Factors Influencing Vehicle Audio Speaker Locations for Better Sound Quality and Spread | The NVH performance of today's automobiles has been improved to levels where common user can easily perceive the issues related to sound quality inside the passenger compartment. With NVH development resulting in quieter and quieter driving conditions, the importance of better acoustic in car-entertainment has been improved by 2-3 notches. The focus of this paper is further concentrated on the methodology to evaluate and optimize speaker location in a MPV. The speaker location was optimized for its location inside passenger compartment and its mounting characteristics. Two different configurations of speaker fitment locations for different seating patterns were tested in vehicle. Frequency Response Function and sound quality parameters were measured experimentally and calculated using sound quality algorithm respectively. The optimal position of speaker location is then determined by analyzing the data for a) uninterrupted reach of the signal to all passenger locations throughout its frequency range. b) Noise contamination of the source because of reflections from nearby interior components. c) Influence of support stiffness on the source contamination. The evaluation methodology was established as a standard practice for using on different vehicles for speaker location optimization. |
Operating Noise Synthesis on a Class 8 Truck Cab | The objective of this work was to synthesize the time and space average operating airborne noise excitation field from discrete noise sources, to the exterior surfaces of a Class 8 truck cab while operating fully loaded at 60 mph. This noise field was subsequently used as input to a statistical energy analysis (SEA) model, for designing a sound package to reduce interior noise. As a relatively simple and inexpensive alternative approach to direct measurements using a heavy-duty chassis dynamometer in a semi-anechoic chamber, the method nevertheless provided an acceptable input for the SEA development work. |
Using the Hybrid FE-SEA Method to Predict Structure-borne Noise Transmission in aTrimmed Automotive Vehicle | A Hybrid method that rigorously couples Statistical Energy Analysis (SEA) and Finite Element Analysis (FEA) has been used to predict interior noise levels in a trimmed vehicle due to broadband structure-borne excitation from 200Hz to 1000Hz. This paper illustrates how the Hybrid FE-SEA technique was applied to successfully predict the car response by partitioning the full vehicle into stiff components described with FE and modally dense components described with SEA. Additionally, it is demonstrated how detailed local FE models can be used to improve SEA descriptions of car panels and couplings. The vibration response of the untrimmed body-in-white is validated against experiments. Next, the radiation efficiency and vibration response of bare and trimmed vehicle panels are compared against reference numerical results. Finally, interior noise levels in bare and trimmed configurations are predicted and results from a noise path contribution analysis are presented. |
CAE Interior Cavity Model Validation using Acoustic Modal Analysis | The ability to predict the interior acoustic sound field in a vehicle is important in order to avoid or to minimize unwanted noise conditions, such as boom or high pressure levels at cavity resonance frequencies. In this work an acoustic modal analysis is carried out for a minivan. The testing procedure is discussed and some results are shown. With the seats removed and for low frequencies the interior of the vehicle is similar to a rectangular box for which an analytical solution exists. At higher frequencies and with the seat, the interior acoustic field displays complex mode shapes. |
Root Cause Identification and Methods of Reducing Rear Window Buffeting Noise | Rear Window Buffeting (RWB) is the low-frequency, high amplitude, sound that occurs in many 4-door vehicles when driven 30-70 mph with one rear window lowered. The goal of this paper is to demonstrate that the mechanisms of RWB are similar to that of sun roof buffeting and to describe the results of several actions suspected in contributing to the severity of RWB. Finally, the results of several experiments are discussed that may lend insight into ways to reduce the severity of this event. A detailed examination of the side airflow patterns of a small Sport Utility Vehicle (SUV) shows these criteria exist on a small SUV, and experiments to modify the SUV airflow pattern to reduce RWB are performed with varying degrees of success. Based on the results of these experiments, design actions are recommended that may result in the reduction of RWB. |
Prediction and Improvement of High Frequency Road Noise of a Mid-Size Sedan | An airborne SEA model to predict high frequency interior noise is built for a mid-size sedan. The 60 KPH running condition is simulated based on this model and then the corresponding result is compared to the measured interior noise. A very similar prediction is found. Also, weak points of sound insulation and effective absorption area in this vehicle are identified using the model. It is shown that in an early design stage and when the proto vehicle is not available yet, the airborne SEA model is very useful to find out weak points of vehicle sound packages. |
Investigation of Gravel Noise Mechanisms and Impact Noise Transfer | Impact noise, inside a car, due to tire-launched gravel on the road can lead to loss of quality perception. Gravel noise is mainly caused by small-sized particles which are too small to be seen on the road by the driver. The investigation focuses on the identification of the mechanisms of excitation and transfer. The spatial distribution of the particles flying from a tire is determined, as well as the probable impact locations on the vehicle body-panels. Finally the relative noise contributions of the body-panels are estimated by adding the panel-to-ear transfer functions. This form of Transfer-Path-Analysis allows vehicle optimization and target setting on the level of the tires, exterior panel treatment and isolation. |
Long-Range Human Body Sensing Modules with Electric Field Sensor | The authors have developed a long range version human body sensing module. This module has a high measurement accuracy with a capacitance of less than two femto Farads and can detect more distant human bodies compared with conventional sensors. Furthermore, optimizing the electrode structure of this module, noise tolerance and directivity have been improved. We produced some prototypes of this sensor module and evaluated the sensitivity of them in a vehicle. The results show that the prototype can detect a hand at the distance of 300 mm from the sensor electrode. |
A Development And Test Environment for Automotive LIN Network | “LIN-BOX” is designed as a development tool for simulation, implementation and test of the automotive LIN (Local Interconnect Network) control devices or entire network. The tool can be used to simulate master and/or slaves around LIN system. The configurable signal processing makes it possible to simulate and test the communication behavior. LIN-BOX monitors the bus traffic in the vehicle. The data on LIN bus can not only be shown on various windows but also written into log files. LIN-BOX has been used by several cases for debugging and validation, the result shows that it is a powerful tool for LIN cluster design, simulation and test. |
Study cases using the method of Statistical Energy Analyse SEA for airborne sound transmission in a vehicle body | The acoustics insulation on the car body is ones of the more important target in the NVH (Noise Vibration and Harshness) vehicle development process. The method of SEA is a validated statistical approach to solve airborne noise transmission problems. In the vehicle analysis above 300 Hz where material trim and leakage paths makes a important contribution in the vehicle interior acoustics shows the methodology its advantages over deterministic methods. |
Sound Quality Engineering of a New Transport Refrigeration Unit | The redesign of a diesel driven transport refrigeration unit is described, with focus on sound quality goals. Acoustic level and quality goals were set with customer feedback based on jury tests. Sound source levels of specific components were identified, with the noise level of the diesel intake and exhaust, the condenser fan, and noise of the gearbox having the most impact on sound quality. A post-design jury test confirmed the effectiveness of the redesign effort. |
Modeling of Firewall Panel with Laminated Metal using Experiment and Numerical Methods | For the automotive industry, the sound quality inside the vehicles is very important. This importance has increased significantly in the last years within the globally competitive automotive market. The interior vibroacoustic behavior depends on the dynamic characteristics of the car body. Several treatments are used to reduce the structural energy of the body panels. For instance, it may be applied passive damping technology, by use of viscoelastic materials, to control their noise and vibrations. This paper presents a comparison of the vibroacoustic characteristics of two firewall panels, made with normal and quiet steel. Experimental and numerical (FEM and BEM) techniques are used to get modal and acoustic data. |
Scan & Listen: a simple and fast method to find sources | The particle velocity field close to a source almost matches the surface vibration whereas the sound pressure field is mainly caused by the background noise. Here a new method is proposed that is to simply listen to the particle velocity field to find sources. The method shows to give a very fast first impression of the acoustic problem at hand. |
Seat/Floor Coupling CAE Study for Body/Vehicle NVH | In today's competitive automobile environment with shorter vehicle development time and fewer prototypes/tests, CAE is becoming very crucial for vehicle development. Seat is a critical system of automobiles for customer satisfaction because seat provides support, safety, and comfort especially NVH for vehicle occupants. In this paper, the effects of seat system on body and vehicle NVH were studied. How the seat system affected body and vehicle NVH, and how seat to floor coupling affected vehicle NVH were investigated. Two groups of finite element body models, body-on-frame and unitized body, were used for this study to ensure the effect of body architecture was included in this study. In the baseline body models, the seats were represented by detailed finite element models. Then, several versions of body models were built by modeling seats in different finite element representations. Three critical vehicle road load cases (engine idle, coarse road at 30mph, and rough road at 40mph) were investigated in this study. Body NVH performance (local/global modes and seat track/floor attachment responses) and vehicle road NVH performance (front/rear interior sound and seat track/floor attachment vibration) of different body versions were assessed against that of baseline models. The conclusions would determine the seat contribution (seat/floor coupling) for body/vehicle NVH performance. The results would also guide the seat modeling methods for body/vehicle NVH CAE analysis. |
NVH Optimization for Passenger Car Thermal Systems | Noise and vibration of passenger car thermal systems are some of the major contributing factors to customer satisfaction. The optimization of these characteristics requires an integrated approach involving detailed analysis, simulation and testing. This paper describes selected noise, vibration and harshness (NVH) issues, discusses solutions and provides examples of its successful applications for thermal systems in passenger cars. The major components of a thermal system include condenser, radiator and fan module, main HVAC module, auxiliary HVAC module as well as air conditioning (AC) additional components such as lines, seals, hoses and vibration isolators. All components can contribute individually or as a system to the noise problem. Significant sound level reductions and improvements in sound quality have been achieved applying detailed analysis, Computer Aided Engineering (CAE) tools, and advanced testing methods. Examples presented in this paper include an auxiliary HVAC module of half the size and equivalent overall sound level compared to past designs, considerable reductions in objectionable noises such as aspirator and defrost bleed noises, and improvements in vibration through optimized placement of stiffening members. |
Integrated Approach and Ideas for Designing Lightweight NVH Parts in Passenger Vehicle | The Interior noise is now one of the signatures of passenger vehicles. It contributes significantly to a customer's perception of quality. The vehicle acoustic package can be an important piece to the acoustic signature, and can be used not only to reduce sound level inside the vehicle but also to shape the sound such that it meets the expectation of customer and increasing competition between the Vehicle Manufacturers. The conflicting objective of maintaining high Noise, Vibration and Harshness (NVH) characteristics at the same time reducing the weight of the vehicle is a major priority within the Automotive Industry. Moreover to meet ever-growing demand to minimize emission and to achieve greater efficiency from automobiles, there has been a constant effort to reduce the weight of the vehicle body structure along with improving NVH of vehicle. This paper reflects various measures used in the new generation automobiles to provide a superior acoustic package to the customer for a quite and pleasant drive along with improving vehicle body structure by means like bead pattern optimization and tailor rolled blank design in terms of weight reduction to give a highly efficient and greener car for creating greater customer satisfaction. |
Application of Acoustic FEA to the Automotive and Aircraft Industry | Numerical simulation techniques are widely used in automotive and aircraft sectors. The optimization of industrial products with respect to acoustic performance requires appropriate modeling strategies in order to handle various noise sources and different propagation paths. The present paper focuses on the application of finite element techniques (FE) to the solution of vibro-acoustic and aero-acoustic problems. State-of-the-art FE techniques are reviewed and illustrated by appropriate examples. |
Difficulties Encountered in the Correlation of Vehicle Response to Bench Testing of Driveline Gearboxes for NVH Attributes | Correlating a bench test stand to predict the response of a driveline gearbox in the vehicle can be very difficult. Many sources of variation and error may prevent correlation. This paper outlines the issues related to both vehicle and bench testing that prevents proper correlation. The importance of understanding both the NVH measurements and statistics are vital to proper interpretation. The identified issues are backed up with real test cases where these issues occurred in a series production gearbox program. A successful correlation case study is presented for comparison. |
Predicting the Acoustics of Squeak and Rattle | This paper discusses the development of a computationally efficient numerical method for predicting the acoustics of rattle events upfront in the design cycle. The method combines Finite Elements, Boundary Elements and SEA and enables the loudness of a large number of rattle events to be efficiently predicted across a broad frequency range. A low frequency random vibro-acoustic model is used in conjunction with various closed form analytical expressions in order to quickly predict impact probabilities and locations. An existing method has been extended to estimate the statistics of the contact forces across a broad frequency range. Finally, broadband acoustic radiation is predicted using standard low, mid and high frequency vibro-acoustic methods and used to estimate impact loudness. The approach is discussed and a number of validation examples are presented. |
TEST EQUIPMENT MAKER'S COOPORATIVE APPROACH TO THE MEASUREMENT NEXT GENERATION AUTOMOTIVES: COMPARISON OF NOISE AND VIBRATION CHARACTERISTICS BETWEEN ICE VEHICLE AND EV | The car's ride of electric vehicle (EV) is quite different from that of internal combustion engine(ICE)vehicle. Nonetheless, only limited discussion has held so far. We have carried out noise and vibration measurements using EV in order to compare to ICE vehicle. We have found that sound quality index in addition to sound pressure level are useful to evaluate distinguished sound of EV. Also, the characteristics of sound field in cabin are found to be quite different each other. |
Improving SEA Predictions with Experimental Data | Statistical Energy Analysis (SEA) has been used widely by industry and academia for more than 20 years to predict the mid-to-high frequency range behavior of complex acoustic systems. At Gulfstream Aerospace Corporation (GAC), SEA models have been developed to predict the interior cabin noise levels of completed Gulfstream aircraft. These models are also used for acoustic evaluations of design changes prior to implementation as well as a diagnostic tool for investigating noise and vibration issues. Throughout the development of the SEA models, extensive experimental testing in GAC's Acoustic Test Facility (ATF) was conducted on numerous aircraft components represented in the models. This paper demonstrates the importance of using experimental data to improve the accuracy of the SEA predictions by accurately adjusting the material properties and acoustic parameters of the SEA model to better match the ATF experimental data. This is particularly important for complicated SEA models with thousands of subsystems and junctions. |
Prediction of Vehicle Interior Sound Pressure Distribution with SEA | Statistical Energy Analysis (SEA) is the standard analytical tool for predicting vehicle acoustic and vibration responses at high frequencies. SEA is commonly used to obtain the interior Sound Pressure Level (SPL) due to each individual noise or vibration source and to determine the contribution to the interior noise through each dominant transfer path. This supports cascading vehicle noise and vibration targets and early evaluation of the vehicle design to effectively meet NVH targets with optimized cost and weight. A common misconception is that SEA is only capable of predicting a general average interior SPL for the entire vehicle cabin and that the differences between different locations such as driver's ear, rear passenger's ear, lower interior points, etc., in the vehicle cannot be analytically determined by an SEA model. However, because the interior acoustic energy distribution varies due to absorption and distance effects that can be modeled, an SEA model is capable of predicting the SPL at different interior locations with good accuracy at high frequencies. This paper discusses the SEA modeling assumptions used to generate a typical model of a vehicle cabin interior and surrounding structure. The distribution of acoustic absorption and its effect on the local interior SPL responses are addressed. Measurements of transfer functions to various points of the vehicle interior from exterior and interior acoustic sources and structureborne sources for a typical vehicle are presented and compared to SEA model predictions. Observations and recommendations about typical interior transfer function correlation, modeling limitations, and use of the SEA model as a design tool are given. |
SEA Wind Noise Load Case for Ranking Vehicle Form Changes | Vehicle manufacturers demand early design assessment of vehicle wind noise attribute so as to eliminate engineering waste induced by late design changes. Vehicle wind noise attribute can be simulated with a Statistical Energy Analysis (SEA) model using exterior surface turbulence pressure on the vehicle greenhouse panel as the wind noise load. One important application of SEA wind noise model is the wind noise assessment for vehicle form design. Vehicle form optimization for wind noise plays an important role in lightweight vehicle architecture, since that reduction in the wind noise load will compensate the loss of vehicle body acoustic attenuation caused by down-gauge glazing and body panels. In this paper, two SEA wind noise load cases currently used in vehicle SEA wind noise modeling have been analyzed and evaluated against vehicle measurements. Two types of evaluations have been made: prediction of the interior cabin noise level at driver's ear location and simulation of level change in the interior cabin noise corresponding to different exterior mirrors. The correlation result shows that current wind noise load cases over-predict the interior cabin noise and mis-simulate the level change in interior cabin noise in response to mirror shape change. A new SEA wind load case has been proposed. The prediction of the interior cabin noise from the proposed load case shows a good correlation with vehicle measurement. The correlation result shows that the proposed load case improves the simulation of change in the interior cabin noise in response to mirror shape change. Further effort is needed to improve the determination and representation of acoustic energy in the pseudo acoustic near field. |
An Efficient Modeling Approach for Mid-frequency Trim Effects | In traditional FE based structure-borne noise analysis, interior trims are normally modeled as lump masses in the FE structure model and acoustic specific impedance of the trim is assigned to the FE acoustics model when necessary. This simplification has proven to be effective and sufficient for low frequency analysis. However, as the frequency goes into the mid-frequency range, the elastic behavior of the trim may impose some effects on the structural and acoustic responses. The approach described in this paper is based on the structural FE and acoustic SEA coupling analysis developed by ESI, aiming to improve the modeling efficiency for a possible quick turnaround in virtual assessments. The idea is to reassemble the FE-SEA hybrid analysis results for the trimmed condition by combining radiated sound power from untrimmed body structure with trim component absorption, insertion loss data and other necessary information which can be extracted easily and quickly from an untrimmed FE model, and/or SEA model. |
Reconstruction of Vibro-Acoustic Responses of a Complex Vibrating Structure Using Helmholtz Equation Least Squares | This paper presents an experimental study on using the Helmholtz equation least squares (HELS) based nearfield acoustic holography (NAH) method for reconstructing the vibro-acoustic responses on the surfaces of arbitrarily-shaped structures. Specifically, we demonstrate the capability of HELS to reconstruct normal surface velocity (NSV) and perform panel contribution analysis. The test object is a hexagonal-shaped structure made of eight panels and frames that mimic a scaled automotive passenger compartment. The test was conducted inside a fully anechoic chamber with the structure excited by a point force using random input signals. The radiated acoustic pressures were measured via a linear array of microphones at a very close distance to the structural surfaces, and taken as the input to the HELS codes to reconstruct NSV and surface acoustic pressures (SAP). The first part of the study establishes the accuracy of the HELS reconstructions by comparing the reconstructed NSV to the benchmark NSV directly measured using a laser vibrometer. The second part is panel acoustic contribution examination (PACE) that utilizes the reconstructed NSV and SAP to determine the normal-component of the time-averaged acoustic intensity on the panel surfaces. The relative contributions from individual panels toward sound pressure level at any field point inside the compartment are determined by summing the acoustic power flow from individual panels to the field point. PACE enables one to establish the ranking of each panel for its contribution to the sound pressure level (SPL) at any field point, say, the driver ear position. The major advantage of using the HELS approach is that it can characterize the structure-borne noise on the source surface and surrounding fluid medium, as well as determine the panel contributions toward SPL values at any number of field points based on a single set of pressure measurements. |
Scan and Paint for Acoustic Leakage Inside the Car | Leakage ranking of vehicle cabin interiors is an important quality index for a car. Noise transmission through weak areas has an important role in the interior noise of a car. Nowadays the acoustic leakage inside a cabin can be measured with different techniques: Microphone array-based holography, Trasmission loss measurement, Beamforming analysis, Sound intensity P-P measurements and ultrasound waves measurements. Some advantages and limits of those measurement approaches for quantifying the acoustic performance of a car are discussed in the first part of this paper. In the second part a new method for fast leakage detection and stationary noise mapping is presented using the Microflown PU probe. This method is called Scan & Paint. The Microflown sensor can measure directly the particle velocity which in the near field is much less affected by background noise and reflection compared with normal microphones. This makes the sensor very suitable for measurements inside a complex and reactive environment like the interior of the car. A camera is used to film the sweep measurement procedure of some surfaces in the cabin interior of a Toyota Avensis. The audio data is processed and synchronized with the video data. A velocity or intensity colormap can be calculated for the different interior parts of the car under test. |
Improved Noise Source Identification Using Sound Quality Metrics Mapping in Vehicle Noise Measurements | A method of mapping a sound field using sound quality metrics has been investigated with an aim of identifying noise sources based on their sound characters rather than traditional measures such as sound pressure level (SPL) and intensity. The method having 11 metrics was implemented in four different array applications, namely near-field acoustical holography, planar beamforming, spherical beamforming, and patch acoustical holography. The sound quality metrics (SQ) mapping was applied to diesel engine measurements as well as vehicle interior measurements. In both applications, there have been a number of attempts to identify impulsive noise sources and therefore in this investigation an impulsiveness metric was developed. The proposed metric was validated against ideal impulses as a function of impulse repetition frequency, amplitude and duration of impulses. The results of noise source identification in both applications revealed that the proposed impulsiveness mapping enabled the detection of impulsive or rattling sources to be more effective compared to the use of SPL and intensity. Furthermore, a number of potential improvements on the SQ mapping are discussed. |
Sensation and Measurement of Low and Very Low Frequency Time-Varying Sounds in Accordance with the Very Short Impulse Response of Low-Frequency Human Hearing | Human hearing, with its active transducers, attention process and remarkable signal-processing abilities, challenges the transportation-product sound quality engineer to measure accordingly and has clearly given rise to the practice and tools of sound quality engineering. Transient events and/or level changes of various durations and magnitudes and over various frequency bandwidths are measurable with due care in the majority of “real-world” acoustic time-signal histories, and frequently carry subjective importance. Inspired by recent work with wind-turbine sound situations, the focus of this paper is to suggest reconsideration of some low-frequency measurement methodologies in the transportation realm. Results will be presented coherent with the hearing system's unusually short impulse response at low and very low frequencies (principal magnitude within about 10 milliseconds, slight effect to about 75 milliseconds), which make low-frequency impressions not only sensitive to time variation, but even to very short-term transitory levels. Hearing-event evaluation is strongly weighted by short-term near-peak values not revealed in overall results and largely erased in conventional constant-percentage-bandwidth measures versus time such as 1/3-octaves. This sound quality concept is generally known and applied at mid and high frequencies, but would be productive to extend to low and very low-frequency sensation and measurement. |
Measuring Damping Loss Factors of High Performance LASD Coatings | One of the most effective NVH solutions used in the automotive industry to reduce structure-borne noise is to apply vibration damping treatments to the vehicle structure. These damping treatments need to meet increasing weight reduction targets, while offering the same or better damping properties. While Liquid Applied Structural Dampers (LASD) are now delivering high damping performance at lower densities, traditional damping measuring techniques are falling short in describing the performance of these extensional layers when applied onto more realistic test samples or real structures. This paper discusses the damping performance of LASD technology, in particular the newer generations of acrylic-based waterborne LASD materials, which through improvements in polymer architecture are achieving increased damping efficiencies together with reduced density. The paper further describes a test method for evaluating the composite damping loss factor (CDLF) properties of LASD treatment layers applied to metal panels used as test samples. The panel test method is based on the calculation of the reverberation time as determined from the initial decay rate of the band filtered impulse response functions. The damping data determined by using this test method is found to be in good agreement with similar data measured independently by using power injection methods (PIM). Correlations between damping performance of LASD treatments measured by using panel testing, one dimensional beam testing, and body-in-white testing methods are also discussed. The damping measurement technique described was used as a validation tool for the latest generation, lower weight, high performance, LASD materials. Panel measurements correlate well with existing test techniques and provide useful information on damping performance, in a high modal density environment, which can be used as input into advanced NVH modeling techniques. |
Damping Mass Effects on Panel Sound Transmission Loss | The primary function of damping treatment on a vibrating panel in a vehicle is to reduce vibration levels or radiated sound power by the dissipation of energy. However, in automotive applications the mass effects of damping materials should not be ignored, especially with regard to airborne noise performance. In this paper, a Finite Element-Statistical Energy Analysis (FE-SEA) hybrid analysis is used to evaluate the mass effects of applied damping materials on Sound Transmission Loss (STL). The analysis takes into consideration effects on both the elastic properties and modal mass of the panel. It is shown that while uniformly distributing the mass of the damping material over the panel generally over-estimate the mass effects on STL, an area weighting approach underestimates the effects. Results are confirmed by laboratory testing. A nomogram is generated to show the total effect of the mass of the damping material on STL. |
Simulation of Noise Reduction in Passenger Trains Using Metal Foams | One of important problems in railway transportation systems is control of noise and vibration. Metal foams are very good medias for absorbing noise. So in this paper, noise of motion of a train is simulated by MATLAB software and the reduction of noise level in a compartment of passenger car that is equipped by metal foam sheets is considered. Commonly, the sound absorption coefficients are obtained experimentally and they are available in datasheets and references. The different parameters that influence on the capability of this equipment were considered. For example the microstructure, thickness, magnitude of compaction, relative density and etc of metal foam is effective parameters. High porosity has good effect on the performance of absorber sheet. By increasing of compaction ratio, in frequency domain we will have enhancing of absorption of the noise. Compaction process is done by two different ways: one is direct and else is progressively. Relative density has inverse relation with reduction of sound pressure level. So with these considerations the absorption ability of metal foams is less than glass wool as one of the best available noise absorbers in industry. But by changing the microstructure such as rolling, compaction and derailment and also increasing area of used metal foam, we can achieve to high level performances. |
Spirit AeroSystems Acoustics Lab: Measurement and Analysis Capabilities | Previously part of a larger OEM, Spirit AeroSystems became a standalone company 5 years ago and is currently a Tier One supplier of aerostructures. Products include fuselage components, wing structures, engine struts and nacelles, and at the request of various OEMs, fully stuffed fuselages and podded engines where all of the wiring, heating, duct work, etc. is installed prior to delivery. While operating as part of the Propulsion Structures and Systems Business Unit, the design, testing and analysis services provided by the acoustics lab potentially impact all programs at all stages of development because of increasing noise regulations and material certification requirements for implementation in high noise environments. In order to address these issues, the acoustics lab has three main objectives: support design and development of engine nacelle lining technologies, ensure components meet structural fatigue requirements and ensure aircraft interiors meet noise regulation exposure limits. Historically, the primary focus of the lab has been the development and testing of acoustic liners and their components and qualification of assemblies and materials that will be exposed to high level noise environments. One objective of this paper will be to discuss the methods used to design, develop, and verify the performance of an acoustic liner and the structural integrity of not only the acoustic liners but any assembly or material installed in a high level noise environment. A second objective will be to discuss the development of new testing and analysis capabilities that arose from the relatively recent requirement to address structural acoustic and interior noise requirements. |
A Pragmatic Approach to Production NVH Test of Seat Adjusters | A powered seat adjuster is a complex mass-produced assembly that is heavily optimized for low cost and light weight. The consequence is an inevitable degree of uncontrolled variation in components, subassemblies, and final product. Automakers are driving an exceptional focus on quality and the showroom experience of the car buyer is paramount. Therefore, any seat adjuster with the potential to not satisfy the customer's expectation is likely to be screened on the production line. This paper describes NVH metric design in the context of automated production line detection of seat adjuster defects. A key requirement of the production environment is that the metrics offer intuitive explanations of possible defects and are based on industry-standard formulations. The metric set is a hybrid of objective and subjective parameters with a focus on ensuring a robust sorting process that maximizes detection while minimizing the possibility of failing acceptable product. As a set, the metrics are therefore capable of correlation to human subjective impression of the seat track sound as well as direct indication of specific defects that may fail one or more objective metrics. |
Practical Considerations of Driveline Vibration and Acoustic Test Cell with Case Study of McLaren's Driveline Dynamometers | Test Facilities for Vibrations and Acoustics can be very complicated. With the addition of necessary high power motor dynamometers for load application, the complexity of the test cell increases dramatically. The motors and subsequent additional fixtures and shafts necessary to apply loading conditions can produce additional source noises that would interfere with test measurements. In addition, facility interfaces can dramatically influence the test cell setup and reduce the measurement capabilities. This paper addresses common considerations needed in considering a new test cell for driveline vibration, acoustics, efficiency, and durability testing using motored dynamometers. In addition to outlining common design points, a practical application of 2 new dynamometers utilized for vibration, acoustics, efficiency, and durability testing and their subsequent capabilities are outlined. |
VALIDATE - Basis for New Sophisticated Research Platform for Virtual Development of Vehicle Systems | The Stuttgart Driving Simulator currently under construction at the University of Stuttgart makes out the main component of the University's new automotive research platform. The facility will be one of the largest of its kind in Europe. The simulator is based on a powerful eight axes motion system to realistically recreate the linear and rotary motion as perceived by the driver during a real trip. To add further value to the driving simulator, it is designed to house a real vehicle which can be easily exchanged - from small passenger cars up to large luxury sedan vehicles as well as SUVs. To assure a sound testing environment, the driving simulator features a realistic graphical and acoustic representation of the vehicle environment such as roadway, environment, and traffic. This is achieved through a complex surround visualization system with very high level of detail as well as an advanced spatial acoustic noise generator. Additional to this, high-quality dynamic force feedback systems at the control elements (pedals, steering wheel, gear stick, etc.) ensures a realistic vehicle and driver milieu. The research platform currently set up is predominantly specialized for energetic topics within the automotive research and development and hence well suited for contemporary topics like sustainable mobility. A major research topic will cover the field of driver influences. With the measurement vehicle, as a further component of the research platform, a first, for German conditions representative study, has been conducted. The acquisition of the driving resistances and power flows in IC, the onboard electrical system, auxiliaries, exhaust system, and cooling system during real drives confirms the strong influence of the driver on the fuel consumption and thus the CO₂ emissions. On average, the driver accounts for a 6.5% fuel consumption variation and in a standard situation variations in fuel consumption up to 65% due to driving style have been measured. Based on the knowledge about the saving potential in various driving situations, appropriate assistance systems can be designed and qualitatively and quantitatively tested and verified in the new driving simulator environment. |
Optimum Constraint Strategy for Liftgates | The present study defines the functional requirements for a liftgate and the body in order to avoid rattle, squeak, and other objectionable noises. A Design For Six Sigma (DFSS) methodology was used to study the impact of various constraint components such as bumpers, wedges, and isolated strikers on functional requirements. These functional requirements include liftgate frequency, acoustic cavity frequency, and the stiffness of the liftgate body opening. It has been determined that the method of constraining the gate relative to the body opening has a strong correlation to the noise generated. The recommended functional performance targets and constraint component selection have been confirmed by actual testing on a vehicle. Recommendations for future liftgate design will be presented. |
Experimental Analysis of the Filter Element Influence in A/C System | The study objective is to evaluate the thermal comfort and vehicle safety emphasizing on air-conditioning system. Several aspects of automobiles thermal comfort are associated with security issues as the windows defogging and defrosting, and air quality inside the vehicle. For the automotive industry, constant air flow in the vehicle is the reason of continuous research on the improvement of the stream and quality of the air that reaches the occupants. This work presents flow bench and vehicle experimental tests results ass an evaluation of the possibilities of the filter element improvement, for the flow, air filtering and temperature adjustment optimization inside the vehicle. Comfort and safety evaluations were made by the air stream inside the vehicle and experimental tests in a climatic chamber. All the tests were made in the same vehicle. Local head losses were evaluated at the flow bench and the vehicle conditioning at the climatic chamber. The pressure inside the vehicle was analyzed during the flow variation, to ensure a comfortable condition for vehicle occupants. |
Door Latch Strength in a Car Body Environment | Federal Motor Safety Standard (FMVSS) 206 regulates the minimum strength of side door latches in passenger carrying vehicles. The purpose of the standard's requirements is “to reduce the likelihood of occupants being ejected from vehicles in real world accidents.” Investigation of unwanted door openings during accidents has revealed various types of latch failures that do not produce latch and/or striker damage consistent with that found in Federal Motor Vehicle Safety Standard compliance testing. An intersection collision in which a striking vehicle contacts the struck vehicle aft of the affected door has for many years been considered the “most critical to door latch performance” (1). This type of car to car collision will often result in structural separation of the door end panel, “B” post striker panel or latch/striker assembly. These structural failures combine tensile and shear loading on the latch/striker assembly. This paper defines the state of the industry with regard to vehicle door latch strength using a simple testing method that produces door latch separations more consistent with common intersection side impact collisions. The test methodology simultaneously applies both longitudinal and lateral loads as the vector sum of the FMVSS 206 defined loads. To place the test findings in perspective, results are normalized using the existing 206 requirements. |
Development of Cabin Air Quality System | In recent years, concern among car users regarding air quality has been steadily increasing. Pollen and diesel vehicle exhaust gases entering the cabin and smoke from fellow passengers not only reduce the quality of experience for everyone in the car, but are also harmful to the health. Therefore, we developed: 1 A low pressure loss, dust-removing, selectively deodorizing filter that effectively absorbs malodor from diesel vehicle exhaust gas, without affecting A/C performance. 2 An automatic intake door control system that excludes outside exhaust gas 3 An optic catalytic air purifier with germ removal and long life deodorizing functions. We here report on the system combining these functions. |
Effects of Vehicle A-pillar Shape on Local Mean and Time-Varying Flow Properties | Separated flow is the main generator of aerodynamic noise in passenger vehicles. The flow around the A-pillar is central to the wind noise as many modern vehicles still have high fluctuating pressures due to flow separations in this region. Current production vehicle geometry is restricted due to the amount of three dimensionality possible in laminated windscreen glass (and door opening etc). New materials (e.g., polycarbonate) offer the possibility of more streamlined shapes which allow less or no flow separation. Therefore, a series of experimental investigations have been conducted to study the effects of the A-pillar and windshield geometry and yaw angles on the local flow and noise using a group of idealised road vehicle models. Surface mean and fluctuating pressures were measured on the side window in the A-pillar regions of all models at different Reynolds numbers and yaw angles. Flow visualisation was also used to see the flow structure and supplement the surface mean and fluctuating pressure data. Frequency based analysis was conducted. The studies show that depending upon the curvatures of A-pillar and windshield, the fluctuating pressure coefficients can be reduced significantly. Reynolds number sensitivities were minimal and the surface mean and fluctuating pressures can be scaled if no feedback mechanism is present. A relationship between the surface fluctuating pressure coefficients and local A-pillar radii was established. |
System Design Parameters in Determining Automotive Sidelite Glazing Performance | A study has been conducted to develop design criteria for materials for use in glazing systems and to identify the parameters affecting actual intrusion-resistance. The intent is to be able to provide the automotive consumer with enhancements in occupant security and safety through incorporation of enhanced protective glass (EPG) in body glass locations. Based on actual sidelite attacks and measurements of human applied forces, an appropriate and comprehensive test methodology has been developed. The test method extends beyond simple impact by providing a measure of the applied force or energy to gain entry to the vehicle through the sidelite as installed in a vehicle. Tests have revealed that the performance level depends not only on the particular glazing type utilized, but how it engages with the door system which in turn controls the in-service performance. Information generated by this methodology has compared favorably with time-to-vehicle-entry obtained from direct human attack. This type of comprehensive testing has provided valuable information for guiding glazing development and outlining parameters for proper design of door systems. The sidelite testing and product evaluation has also provided insight into factors which relate to occupant interaction and safety when occupant contact with body glass occurs. Many of the relationships overlap between occupant security and safety, such that, if a reasonable degree of intrusion-resistance is provided, there will be a commensurate benefit in occupant safety (c.f., ejection-mitigation). |
ISS Crew Refrigerator Freezer Rack - Comparing EcosimPro and ESATAN Modeling | The Crew Refrigerator/Freezer Racks (RFR) are being developed and built at Astrium Friedrichshafen under ESA contract. The RFR will provide conditioned storage volume for astronaut food during transport in the MPLM and on board the ISS. To support the design of the RFR a thermal model has been established at Astrium in the early project phase using the ESATAN software which is the ESA standard thermal analysis tool. This model has been extended to allow full operational simulation of the RFR during a typical mission scenario. For demonstrating the capabilities of EcosimPro, a state of the art tool to address Environmental Control and Life Support analysis, the same model is built up with EcosimPro. The results are validated by comparing them to those from the ESATAN simulation. Three simulation cases are investigated: steady state operation mode, 8 hours passive period with increase of ambient temperature from 30°C to 49°C and recovery, door opening every 3 hours for up to 30 seconds at ambient temperature of 30°C. |
“A Dry Aircraft is a Safer Aircraft – Beating Condensation by Using Dry Air” | The airline industry seems to be providing more leisure features on planes like inflight entertainment, Internet access and Digital TV, but it seems the airline industry has ignored the issue of excess condensation on aircraft, which had plagued carriers since the birth of the airline industry. How safe are passengers when a wide body aircraft carries in excess almost a half ton of water and ice between the cabin and skin of the aircraft? Besides the added weight straining the aircraft, excess condensation soaks wires and connectors which can cause electrical shorts. There have been instances of emergency doors frozen shut, locked by ice stemming from excess water dripping inside the plane. Extra water also causes “rain-in-the-plane”, an issue that has gained national attention and causes passenger discomfort. It's time for the industry to address what has become a serious issue. With decision makers searching for an answer on how they can ensure their passengers' safety, one way is to prevent excess condensation in aircraft. Up until now, solutions were expensive, temporary and vacuous. CTT has taken the lead in addressing these problems and understanding the root causes. They have developed technology to which addresses these problems economically and permanently. With commercial airlines searching for the answer, CTT can present strategies to prevent these problems and help airline executives keep their passengers as safe as possible. The speaker is the CEO of CTT Systems. The company developed a system that solves the condensation by using dry air. |
Peugeot Fractal demonstrates a new take on sound design | Peugeot used the 2010 SR1 concept to introduce its i-Cockpit touchscreen-based system, designed to control heating and ventilation, navigation, audio, connectivity, and the trip computer. The first-gen system entered production in the 2012 Peugeot 208. The company took the i-Cockpit concept one stage further in the Fractal electric urban coupe concept at the 2015 IAA Frankfurt Show, to include sound. The concept plays a “sound signature,” created by DJ and sound designer Amon Tobin, which is triggered when the driver opens the car using the smart watch remote locking system. “Behind this concept of an electric car-that is not really new, there was this question that electric cars emit no sound,” explained Matthias Hossann, Head of Concept Cars and Advanced Design at Peugeot. |
Momentum, the Magazine for Student Members of SAE International 2010-09-01 | High-speed education @ formula hybrid event Annual competition provides a hands-on learning experience for undergraduate and graduate engineering students. Body-shaped for supermileage Six different single-occupant vehicles designed and built by teams of collegiate engineering students snared four-digit fuel economy at Eaton Corp.'s Marshall, MI, test track during the 31st annual SAE Supermileage competition in June. Mercedes-AMG goes with the current flow Opening the doors on new technology. First flight approaches for 'disruptive' new UAV engine An earlier iteration of UAS' Nightwind 2 in flight, powered by an off-the-shelf industrial engine. Three resume tips for college grads Employers often hire recent graduates to mold new hires to their own corporate culture and work philosophy, leading some employers to look more for potential than for specific experience. SAE, Deere announce 'learn twice' initiative Students involved in SAE International's Collegiate Design Series can get their team's registration fee reimbursed by working with local elementary and high school teachers to teach science, technology, engineering, and math concepts through the "A World In Motion" curriculum. EngineerXChange being launched to help attract younger members With the launch of EngineerXchange in October, SAE is hoping to communicate with young engineers via the Web and social media. |
Automotive Engineering: March 2021 | Engineering Ford's future Product platform and operations chief Hau Thai-Tang on navigating the microchip shortage, compact-unibody trucks, EV and AV challenges, and driving engineering efficiencies amid the lockdown. NAWA aims for 5-minute EV charge A new nano-based carbon electrode is key to reducing electric-vehicle charging time. Hemphill's mission: Support the innovation ecosystem Schaeffler America CTO Jeff Hemphill brings impressive technical chops and well-honed communication skills to his new role as 2021 SAE International president. Editorial The legacy of the pioneering, controversial EV-1 SAE Standards News Help wanted: SAE tech standards committee, task force seeks new members SUPPLIER EYE Electrification and the Two-Cycle Imperative Electrified Corvettes in development German OEMs flex 3D manufacturing muscle ZF builds 'middleware' to address vehicle software escalation TDK unveils power-generating wheel sensor Bosch consolidates computing talent in new mobility division Ford F-150 Raptor goes 4-door only; R version next year Q&A Celina Mikolajczak, VP of battery technology for Panasonic Energy of North America, discusses The relentless pace of EV battery development and manufacturing |
Momentum, the Magazine for Student Members of SAE International 2012-10-31 | The Nano in retrospect A senior graduate student in the Department of Mechanical Engineering at the Indian Institute of Technology looks at the development of the world's cheapest car and its effect on Indian car users. A different riff on your basic two-seat electric car Markus Lienkamp, Chair of Automotive Engineering at the Technical University of Munich, is leading the Visio.M project, a German government-supported R&D effort to produce a low-cost, high-utility electric car that might attract the interest of the middle European mass market. Materials lead the way to vehicle mass reduction Reducing a vehicle's mass opens the door for a downsized engine and transmission, a lighter cradle and body structure, smaller wheels and brakes, as well as a weight-slimmed suspension. The start point for this ripple effect is materials. |
Momentum: October 2014 | Buckeye Current's TT triumph The Ohio State University reprised its third-place finish in the 2014 TT Zero for all-electric motorcycles, beating some of the pros on the world's toughest race circuit. Kettering FSAE team improved as season progressed Lowest priced may not mean the best, but certainly not the worst. Leveling the field: getting #girlsinstem Despite facing the brunt of gender segregation, women are forging ahead and dramatically improving STE M, both academically and professionally. Mercedes-AMG's SLS departure opens door to new GT Powering the car is an all-new biturbo 4.0-L V8 available with two power levels: hot (GT) at 340 kW (456 hp) and exceedingly hot (GTS) at 375 kW (503 hp). |
Analytical and Experimental Approach to Acoustic Package Design | The interior noise signature of passenger vehicles is a significant contributor to a customer's perception of quality. The vehicle acoustic package can be an important piece to the acoustic signature, and can be utilized not just to reduce the sound levels inside the vehicle but also to shape the sound such that it meets the expectations of the customer. For this reason the definition, design, and development of an acoustic package can be vital to meeting vehicle-level acoustic targets. In many situations this development is conducted experimentally, requiring the availability of prototype vehicles and acoustic package components. Of more value is the ability to develop components early in the design phase, leveraging analytical tools to define component-level requirements and targets to meet the vehicle-level targets, and ultimately meet the final customer expectations. This paper presents efforts made to further combine the benefits of experimental and analytical approaches to acoustic package design. The benefits of which include the ability to predict interior sound levels for alternative acoustic package configurations early in the design phase, allowing for listening studies to verify component and vehicle-level targets. Additionally, the performance of alternative designs can be quantified in the frequency domain and using sound quality metrics, while minimizing the necessity for physical testing. A current market vehicle was utilized for this development, in which experimental measurements were developed and conducted for optimum cooperation and utilization of analytical tools. The acoustic package was characterized to predict the sound levels for alternate acoustic package designs, listening studies were performed and metrics were calculated for each configuration to verify performance against the vehicle-levels targets, and developed solutions were verified through experimental testing. |
A CFD/SEA Approach for Prediction of Vehicle Interior Noise due to Wind Noise | For most car manufacturers, aerodynamic noise is becoming the dominant high frequency noise source (> 500 Hz) at highway speeds. Design optimization and early detection of issues related to aeroacoustics remain mainly an experimental art implying high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the development of a reliable numerical prediction capability. The goal of this paper is to present a computational approach developed to predict the greenhouse windnoise contribution to the interior noise heard by the vehicle passengers. This method is based on coupling an unsteady Computational Fluid Dynamics (CFD) solver for the windnoise excitation to a Statistical Energy Analysis (SEA) solver for the structural acoustic behavior. The basic strategy is to convert the time-domain pressure signals generated by CFD everywhere on the panels into structural power inputs, which in turn are used as input to an SEA model leading to the noise inside the cabin. This approach quantifies the windnoise contribution coming from different panels (e.g. side windows, windshield) at various locations inside the vehicle (driver and passenger headspace). In this paper the key technical and numerical aspects of the approach are presented, and interior noise predictions corresponding to real automotive cases are compared to experimental measurements. As examples of the usage, a vehicle exterior shape design study and an acoustic package optimization study are presented. |
A Systematic and Disciplined Process for Developing Drive Files for Squeak and Rattle and Durability Tests in the Lab | The pressure to shorten vehicle product development time-to-launch means more in-lab tests must be performed earlier, and before vehicle prototypes are available for road or test track evaluations. Squeak and Rattle (S&R) evaluations of subsystems/modules and components must be performed using realistic road excitation conditions. How S&R performance degrades as the vehicle, module or component accumulates customer miles or kilometers must be assessed before the design is frozen. Durability tests must be performed earlier in the design/development timeline as well. All these pressures point to having a systematic, disciplined and streamlined methodology or protocol for acquiring and processing road vibration data useful for S&R and durability tests. The protocol must comprehend data acquisition, sampling, and signal processing; properly editing acceleration time histories for either in-lab replication as time histories or as PSD random vibration; creation of drive files that replicate multiple road surfaces; combining multiple road surfaces and speeds into fewer (if not one) tests that replace one-test-for-one-road-condition approaches; selecting overall vibration amplitudes for composite multiple roads; and performing such tests in order to satisfy S&R and durability experts, design/release engineers seeking design validation, and multiple other stakeholders. This paper presents such a protocol based on the expertise from different engineers working on a multitude of vehicle development programs from different companies in different countries over many years. |
A Generic Model for Analysis and Optimization of Fuel Filler Door with Torsional Spring | A mathematical model was developed for the analysis of a fuel filler door with a torsional spring. The model calculates performance indices such as opening and closing forces, kinetic energy during opening and closing and the maximum spring stress. The model was integrated with an optimization program. Two types of optimization problems were formulated: the traditional problem which does not include the effects of random design parameters, and the stochastic type optimization, which does. An example shows how the mathematical model, in conjunction with optimization techniques, can help determine fuel filler door designs. |
Modelling the Dissipative Effect of Seal Air Hole Spacing and Size on Door Closing Effort | Door weather strip seals are designed with ventilation holes spaced at regular intervals along the seal system to expedite the flow of air from the seal system during the door closing process. The flow of air through the ventilation holes represents a nonlinear damping mechanism which, depending upon hole size and spacing, can significantly contribute to door closing effort. In this study we develop one- and two- dimensional versions of a nonlinear damping model for seal compression load deflection (CLD) behavior which incorporate the effects of seal damping response due to air flow through the ventilation holes. The air flow/damping models are developed from first physical principles by application of the mass and momentum balance equations to a control volume of entrapped air between consecutive air ventilation holes in the seal system. Both model formulations indicate that the damping component of seal force per unit length generated during seal compression is directly proportional to , where L and D represent, respectively, the spacing distance and diameter of the air ventilation holes. Numerical predictions for the damping force at a section in a production vehicle door seal system during closing are made using the two models and results compared. |
Door Structural Slam Durability Inertia Relief Approach | The automotive industry faces many competitive challenges including weight and cost reduction to meet CAFE standards. In particular, a thin door panel optimized for weight reduction can cause high manufacturer warranties and durability problems. Traditionally, the assessment of door slam durability is accomplished by tests rather than using computer aided techniques. Many simple CAE techniques such as simple linear static and dynamic analyses have been used to evaluate the door structural integrity. However, the door slam event requires complex analysis due to the transient impact phenomenon. To solve this complex door slam event with a computer based technique is a challenging and interesting problem for CAE engineers. However, a simplified technique has been developed to anticipate the potential durability problem in the door. This technique involves the use of the computer- based finite element method incorporating inertia relief and fatigue life prediction. Actual testing validated the analytically predicted results. This method provides an inexpensive way of predicting door slam durability reducing development time and product cost. As a result, the new approach aided the door design robustness. |
Research on the Application of Aluminum Door Beams for Automobiles | The effect of cross-section and type of alloy on the performance of aluminum extrusions as door beams was investigated. As a result, aluminum door beams were developed which have bending properties comparing favorably with those of door beams made of high tensile strength steel with a tensile strength of 1470 N/mm2. Furthermore, a technology to design door beams with the required performance and bending properties dealing with various car models was developed by making the most of the versatility of aluminum extrusions produced in various types of cross-sections. |
Response of the Eurosid-1 Thorax to Lateral Impact | The Eurosid-1 dummy was subjected to a series of lateral and oblique pendulum impacts to study the anomalous “flat-top” thorax deflection versus time-histories observed in full-scale vehicle tests. The standard Eurosid-1, as well as two different modified versions of the dummy, were impacted at 6 different angles from -15 to +20 degrees (0 degrees is pure lateral) in the horizontal plane. The flat-top deflections were observed in the tests with the standard Eurosid-1, while one of the modified versions reduced the flat-top considerably. Full scale vehicle tests with the standard and modified Eurosid-1 suggest similar reductions. A second series of tests was conducted on the modified Eurosid-1 to investigate the effect of door surface friction on the shoulder rotation and the chest deflection. The data suggested that increasing the friction on the door surface impeded shoulder rotation and ultimately reduced the chest deflection in the Eurosid-1. |