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Development of a Parametric Blend Door Computer-Aided Design System | This paper describes the development of an analytical tool for the design automation of the temperature blend door mechanism in an automotive HVAC system. The function of the blend door is to control the temperature of the air blown into the cabin interior by regulating the mix of air passing through the heater core. The objective in the design process is to achieve a prescribed function of temperature with respect to control position at the instrument panel. The control effort to effect the desired temperature change is also another important consideration for customer satisfaction. The current design process is empirical in nature and relies on laboratory and vehicle testing with prototypes. The process is also iterative in nature and may continue until the end of the overall design cycle of the complete air handling subsystem. A parametric feature-based computer model, described subsequently in detail, allows for virtual prototyping of the blend door control mechanism. With this model, various blend door designs can be explored early in the design cycle. Late changes required for packaging can also quickly be analyzed. Kinematic analysis of the blend door mechanism allows the control curve and control effort to be predictive. This desktop simulation tool will enable designs to be optimized or permit the number of options to be narrowed, which will reduce test time and shorten design cycle time. Illustration of the desktop tool is based upon predicting control curves and efforts for a production HVAC system. Also, airflow and temperature data from CFD analysis for this production system is presented. Finally, predicted results are compared and correlated with actual laboratory and vehicle test data. |
Development of a Film Door Type Air Conditioning Unit | Recently, an increasing demand for comfort has been accelerating the trend toward multifunctional car air conditioners, including zone air conditioning which controls the cabin temperature independently for the driver and the passenger and compensates for the side solar radiation. In addition, the multifunctional air conditioner should be compact to save cabin space and ensure passenger comfort. This report describes the development of a compact and multifunctional car air conditioning unit. |
Design and Development of Automatically Deployed Entry Steps for a Fire Truck Cab | An automatically deployed fold-down step has been developed for use on fire apparatus cabs. The step operates pneumatically as the cab doors are opened. This feature optimizes the ergonomics of cab entry while maximizing the interior space available for occupants and equipment. |
Measures to Quantify the Sharpness of Vehicle Closure Sounds | Impulsive sound events (i.e. door closing) are often characterized as being undesirably sharp sounding. A high degree of perceived sharpness is normally related to large amounts of high frequency energy relative to the low frequency energy. In this project third octave data generated from a filterbank was used to calculate the center of gravity (cg) of the third octave bands. The result is the frequency corresponding to the centroid of the third octave data. Sounds with substantial high frequency energy have a centroid location that occurs at a higher frequency. The mean of the third octave cg over the duration of the transient event was investigated, in addition to sharpness as defined by Aures [1] and calculated on a commercially available analyzer. Correlation analyses to subjective data indicate that the mean third octave cg and the commercially available method produce comparable results for the vehicle closure sounds studied here. Sounds with more high frequency energy during the Initial impact were sharper, while sounds with substantial low frequency energy following the impact were less sharp. |
Extended Cab Side Access Panels - Compact Pick-Up Trucks | In the past, all known, compact pickup truck structures have been limited to the use of two doors to allow for access to the interior regions of the cab. This paper will address the issue of locating a side access panel to an existing vehicle structure, the development criteria used for the panel hinges, the integration of the safety belt system and the advantages of the interior trim attachment methods. Examination will include a review of specific design considerations used to meet governmental and consumer requirements. |
POGO™ Flexible Tooling Universal Holding Fixture for Cutting, Drilling and Assembly in the Aerospace Industry | The aerospace industry has entered a new level of World Class Manufacturing, in which manufacturing functions require fixturing to be just as flexible as the machine tool doing the operation. Flexible tooling has opened new doors for the aerospace industry by creating new tools which are automatically reconfigurable and totally reusable on future programs. Benefits include decreases in non-recurring costs, (such as in the area of tool design and fabrication) and recurring costs, (such as in the area of tool setup / removal and storage). |
Improving Recyclability Through Planned Product Revisions | Whether propelled by a concern for the environment, increasingly stiff legislation, or higher disposal costs, companies are trying to reduce the environmental impacts of their products. At the same time, designers are forced to balance the need to get a product out the door with the desire to improve the product's functionality. Candidate designs are often so constrained that addressing environmental goals proves impossible. In this paper, we discuss the improvement of recyclability for vehicle assemblies through a process of planned design changes over multiple revisions of the product. Specifically, we present the results of a case study describing the creation of a strategy for focusing the recyclability improvement effort to a generic instrument panel (I/P). The possible improvement in recyclability is examined as well as the impact on other design characteristics as the limiting factors for the instrument panel are chosen. Based on this analysis, a plan for focusing the design effort to improve vehicle recyclability is provided. |
Application of a Laser Vibrometer for Automotive Aeroacoustic Analysis | The Scanning Laser Vibrometer can make full field, high resolution measurements of the normal surface velocity of automotive door glass and sheet metal vibrations. These properties make the vibrometer a very useful tool for locating compliant and noisy areas on the surface of a vehicle, generated by exterior wind noise. An advantage of the vibrometer is that it measures the vibration of the surface, capturing the transfer of noise through the surface, rather than simply measuring the exterior wind noise. Methods of experimental setup, testing, and problem analysis on outside rear view mirror/A-pillar/Sideglass configurations and body panel vibrations are discussed in the paper. |
Optimizing Parts and Systems Integration with Engineering Thermoplastics to Meet the Challenges of Future Automotive Door Systems | As automakers struggle to meet often conflicting safety, weight, styling, and performance requirements, engineering thermoplastics (ETPs) are making increasing inroads into applications that once were the exclusive domain of metals, glass, and thermosets. A good example of this is in the door systems area, where the performance, design flexibility, aesthetics, parts integration, and lower specific gravity offered by ETPs are allowing highly integrated and efficient modules to be created that, in turn, increase assembly efficiency and reduce mass, part count, warranty issues, and systems costs. This paper will use several case studies on innovative door hardware modules and door panels to illustrate the advantages offered by this versatile class of engineering materials. |
Development of a Sled-to-Sled Subsystem Side Impact Test Methodology | A sled-to-sled subsystem side impact test methodology has been developed by using two sleds at the WSU Bioengineering Center in order to simulate a car-to-car side impact, particularly in regards to the door velocity profile. Initially this study concentrated on tailoring door pulse to match the inner door velocity profile from FMVSS 214 full-scale dynamic side impact tests. This test device simulates a pulse quite similar to a typical door velocity of a full size car in a dynamic side impact test. Using the newly developed side impact test device three runs with a SID dummy were performed to study the effects of door padding and spacing in a real side impact situation. This paper describes the test methodology to simulate door intrusion velocity profiles in side impact and discusses SID dummy test results for different padding conditions. |
Experimental Assessment of Wind Noise Contributors to Interior Noise | Wind noise reaches the interior of a vehicle through a variety of mechanisms including: aerodynamic excitation of vibration and reradiation from the greenhouse surfaces; acoustic transmission through door seals including gaps and glass edge leaks, and due to airborne transmission of noise generated by wind interaction with body panels. This paper presents experimental results that quantify contributions to interior noise from individual greenhouse surfaces and from airborne sources on the underbody. The measurements were carried out on a production vehicle in a wind tunnel. Greenhouse surfaces, in addition to the driver window are important contributors to interior noise along with airborne transmission of noise generated due to the flow over and through the vehicle underbody. |
Sound Transmission Through Primary Bulb Rubber Sealing Systems | Structural sound transmission through primary bulb (PB) sealing systems was investigated. A two-degrees-of-freedom analytical model was developed to predict the sound transmission characteristics of a PB seal assembly. Detailed sound transmission measurements were made for two different random excitations: acoustic and aerodynamic. A reverberation room method was first used, whereby a seal sample installed within a test fixture was excited by a diffuse sound field. A quiet flow facility was then used to create aerodynamic pressure fluctuations which acted as the excitation. The space-averaged input pressure within the pseudo door gap cavity and the sound pressure transmitted on the quiescent side of the seal were obtained in each case for different cavity dimensions, seal compression, and seal designs. The sound transmission predictions obtained from the lumped element model were found to be in reasonable agreement with measured values. The measured noise reduction was found to be very similar for both types of excitation. This confirmed that an acoustic excitation may be used instead of aerodynamic pressure fluctuations for sound transmission measurements, and that the barrier performance of the PB seal was not significantly affected by the presence of a static pressure gradient associated with the mean flow. The wind tunnel method was also found to yield a better signal-to-noise ratio than the reverberation room method. |
Static and Dynamic Dent Resistance Performance of Automotive Steel Body Panels | In recent years, strict weight reduction targets have pushed auto manufacturers to use lighter gauge sheet steels in all areas of the vehicle including exterior body panels. As sheet metal thicknesses are reduced, dentability of body panels becomes of increasing concern. Thus, the goal becomes one of reducing sheet metal thickness while maintaining acceptable dent resistance. Most prior work in this area has focused on quasi-static loading conditions. In this study, both quasi-static and dynamic dent tests are evaluated. Fully assembled doors made from mild, medium strength bake hardenable and non-bake hardenable steels are examined. The quasi-static dent test is run at a test speed of 0.1 m/minute while the dynamic dent test is run at a test speed of 26.8 m/minute. Dynamic dent testing is of interest because it more closely approximates real life denting conditions such as in-plant handling and transit damage, and parking lot damage from car door and shopping cart impact. The dent resistance performance of the three steel types are examined and compared for both static and dynamic test conditions. |
DEVELOPMENT OF A UNIQUE, GAS-INJECTION MOLDED DOOR HARDWARE MODULE FRAME | A unique design, engineering, and manufacturing approach has been used to create the first all-plastic door hardware module frame. The result of many years of intensive development efforts by a team of companies, the gas-assist injection molded frame features a high degree of parts consolidation and has been critically acclaimed as “the first major metal-replacement automotive part since the bumper, a quantum leap in injection molding complexity, and the biggest commercial breakthrough ever in gas assist molding [1].” The program also proved to be an excellent example of the types of technological breakthroughs that can come from concurrent engineering and strategic partnering. This paper will provide an overview of the component's development, describe the many challenges facing the team, and share solutions that contributed to the success of the program. It will also illustrate the benefits of successfully implementing a design and production strategy that carefully matches design, materials, tooling, and processing. |
Automotive Body Component Field Corrosion Behavior in the De-Icing Salt Zone | Doors were removed from recycle-yard vehicles in Syracuse, N. Y. and examined in the laboratory as part of an on-going field study on corrosion behavior trends in the de-icing salt region of the U. S. Lower doors, including hem-flange internal surfaces, were examined, and performance trends as a function of materials selection, age and mileage were determined. The results to date on doors from 167 Syracuse vehicles are indicative of the nature and history of salt-induced corrosion in the region, and they indicate the degree of benefit from galvanized construction and body design features. |
Material Options for Automotive Interior Trim | This paper outlines the relationship between airbag door choices and instrument panel coverstock materials which are being used in the global automotive market for passenger vehicles as well as those materials that are being considered for use in future vehicles. The introduction of an invisible airbag door into the instrument panel is changing the material and testing requirements as safety and reliability are now key considerations. Increasing material options are available to meet these requirements. In this paper, we review the material options, processing methods available, advantages/disadvantages of each, and the current market status of the different materials. |
Design and Development of a Magnesium/Aluminum Door Frame | This paper describes the methodology by which a combination die cast magnesium and extruded aluminum door frame was developed using a current production steel door design as the base model for comparison. Product performance data, such as side impact requirements and overall door stiffness, along with the packaging of existing internal hardware, is presented. The results are verified by computer modeling. A prototype casting was produced to validate and compare castability requirements and geometry constraints of the door frame. An economic study is included that investigates the potential of developing such a system suitable for production. The results suggest that economic benefits may be obtained by using such a lightweight door system compared to an existing steel door design. |
Measurement of Airborne Noise Reduction of Production Door Components on a Buck | Various automobile door components were evaluated for air-borne noise reduction using production and prototype door assemblies which were modified to fit an SAE J-1400 test fixture. The in-door laboratory evaluation provided a single noise reduction rating in decibels for diverse door assembly components, with different noise reduction mechanisms. This test method overcame some of the shortcomings associated with evaluating each component individually in accordance with an acoustical material test standard. |
Nd:YAG Laser Welding for Automotive Manufacturing Applications | The power output of commercially available continuous wave (CW) Nd:YAG lasers has increased substantially over the last few years. Models which can deliver 4 kW to the workpiece are now available. At this power level, the Nd:YAG laser can effectively compete with the CO2 laser in many laser welding applications. The easier, fibre optic based, beam delivery of the high power Nd:YAG laser makes a number of applications possible which were considered impractical using CO2 laser technology. This paper will first describe the general characteristics of an Nd:YAG laser system as configured for welding, and contrast these features with a typical CO2 laser welding system. Points of discussion include: laser power, beam delivery options, focus spot characteristics including the capabilities of twin spot beam delivery with an Nd:YAG laser, and the interaction of the laser beam with the metal surface, including a brief description of the laser generated plasma. Some specific configurations for an Nd:YAG laser-based weld cell will then be described. In the second section, a number of applications for Nd:YAG laser welding will be described, and sample parts and weld characteristics will be shown. These applications include: welding of tailored blanks for body stampings using 1D and 2D weld geometries, welding of reinforcing patches onto blanks for shock towers, laser welding of hemmed door and hood joints, laser welding of tailored tubes for hydroforming, laser welding of aluminum panels, and laser welding for auto body assembly. The Nd:YAG laser is not expected to replace the CO2 laser completely, but there are a number of applications which are better suited to laser welding with an Nd:YAG than a CO2 laser. The ability to deliver the laser power to the workpiece through a flexible fibre also opens new laser welding applications, and creates more competition for traditional joining techniques. |
Intelligent Audio Amplifier | An intelligent amplifier has been developed which delivers output power to either a two or four speaker audio system. The amplifier determines the number of speakers present during the start-up sequence and configures itself either as two BTL amplifiers or four single ended amplifiers. The system does not require any wiring modifications to operate in either mode and will reconfigure itself on each start-up cycle allowing system modifications, such as adding speakers, without additional wiring or hardware modifications. Difficulties arise when determining the presence of speakers in an automotive environment. Extraneous noise sources such as door slams, hatch slams and engine cranking can cause erroneous measurements thus inappropriate configurations. The presented circuit was determined to be immune to these noise sources and is based upon: 1. Integration of measurements over a fixed period of time 2. Applying a large voltage to overcome noise sources without creating audible disturbances 3. Fixed switch on behavior |
Concept to Production: Continuous Surface Keypad Switch | The objective of this paper is to impart the challenges presented and the solutions derived to transform an artist's rendering into a production driver's door switch to be used in the interior of a high profile sports car. The challenges took many forms throughout the process, from data translation and packaging, to the final decorative issues. The results are a finished product providing a new approach to automotive interior switch design. It incorporates a low profile, continuous plane keypad with “soft touch” feel, tactile feedback, and integrated back lighting. |
Optimized Radii for Draw Dies | This paper deals with the radii of draw dies for sheet metal parts, like fenders, hoods, and doors. For relative flat parts, like hoods, it is important to get at least a 2% forming rate in the middle of the part to reach minimum of stiffness, work hardening, and sufficient geometric accuracy. This can be influenced by the punch radii. Therefore, optimal punch radii should be known. First experimental results about optimal punch radii where published by J.L. Duncan and B.S. Shabel in the SAE-Paper No. 780391. At the Institute for Metal Forming Technology of the University of Stuttgart, Germany, a “Modified Duncan Shabel Test” (MDS-Test) has been developed. This test makes it possible to investigate not only the punch radii but also the die radii. This paper shows optimal punch and die radii as a function of sheet metal, sheet thickness, as well as of the die material. |
High Mileage Squeak and Rattle Robustness Assessment for Super Duty Cab Weight Reduction Using High Strength Steel and Adhesive Bonding | Squeak and rattle is one of the major concerns in vehicle design for customer satisfaction. Traditionally, squeak and rattle problems are found and fixed at a very late design stage due to lack of up-front CAE prevention and prediction tools. An earlier research work conducted at Ford reveals a correlation between the vehicle overall squeak and rattle performance and the diagonal distortions of body closure openings under a static torsional load. This finding makes it possible to assess squeak and rattle performance implications between different body designs using body-in-prime (B-I-P) and vehicle low frequency noise vibration and harshness (NVH) CAE models at a very early design stage. This paper presents an application of this squeak and rattle assessment method for a design feasibility study concerning a cab structure of a super duty truck for weight reduction using high strength steel and adhesive bonding. The study indicates that downgaging and substitution of mild steel with high strength steel combined with adhesive bonding in selected areas of a cab structure can achieve 12.7 Kg (4% of B-I-P) weight reduction without tooling changes while maintaining high mileage squeak and rattle performance of the baseline vehicle. |
High Frequency Effects on Localization and Sound Perception in a Small Acoustic Space | As compared to home audio, the automobile has a different spatial and spectral distribution of sound. This can cause stereo images to blur or shift due to conflicting localization cues. The impact of interaural time and level differences is discussed, along with frequency-selective pinna and head cues. Review of the literature shows that our poorest localization is for mid frequencies (∼2kHz). Yet in an automobile, low frequencies are severely relocated with a minimum effect on fidelity. It is suggested this is because middle frequencies dominate the perception and localization of sound. Therefore, some high frequency information might also be relocated. |
Prediction of Flow-Induced Noise in Automotive HVAC Systems Using a Combined CFD/CA Approach | Noise emission from automotive HVAC systems has become an important factor for passenger comfort. Consequently, efforts are made during the design phase to minimize noise generation, and to improve sound quality. Predictive tools for the aeroacoustic behavior of components, subsystems and whole systems early on in the design phase are therefore desirable. In this paper a combined Computational Fluid Dynamics (CFD) and Computational Acoustics (CA) approach for the prediction of sound generation and propagation is investigated. Three different experimental setups, ranging from a more academic example to examples relevant in the design process of climate control systems, have been devised to provide test data for the evaluation. Experimental and numerical results are presented and discussed. |
Experimental Investigation of the Response of the Human Lower Limb to the Pedestrian Impact Loading Environment | Three limbs were taken from post mortem human subjects and impacted on the lateral aspect by a free-flying (30 km/h) impactor below the knee joint. Tri-axial MHDs and tri-axial accelerometers were used to determine the kinematics of the limb; strain gages were used to measure surface strain on the tibia and femur; and acoustic sensors were used to identify the onset and timing of injury. This data set was analyzed to compute the response of the knee joint to a bumper impact. Post-test necropsy results showed that the primary injury mechanism in each case was complete avulsion of the Medial Collateral Ligament (MCL) and the Anterior Cruciate Ligament (ACL). |
Geometric Visibility of Mirror Mounted Turn Signals | Turn signals mounted on exterior rearview mirrors are increasingly being used as original equipment on passenger cars and light trucks. The potential for mirror-mounted turn signals (MMTS) to improve the geometric visibility of turn signals is examined in this paper. A survey of U.S. and UN-ECE regulations showed that the turn signals of a vehicle that is minimally compliant with U.S. regulations are not visible to a driver of a nearby vehicle in an adjacent lane. Measurements of mirror location and window geometry were made on 74 passenger cars and light trucks, including 38 vehicles with fender-mounted turn signals (FMTS). These data were combined with data on driver eye locations from two previous studies to assess the relative visibility of MMTS and conventional signals. Simulations were conducted to examine the potential for signals to be obstructed when a driver looks laterally through the passenger-side window. With a vehicle population that is fifty percent light trucks, MMTS are visible 52 percent more often than FMTS in this scenario. Based on the lateral visibility analysis, the optimal height for geometric visibility of a signal in the adjacent-vehicle scenario is 124 cm above the ground, approximately the average height of a light truck mirror. A plan-view eccentricity analysis showed that an MMTS is much closer to the viewing driver’s forward-directed line of sight than rear-mounted turn signals when the viewing driver’s vehicle is in or near the blind zone between the signaling driver’s mirror and direct peripheral fields of view. MMTS can improve the geometric visibility of turn signals in the adjacent-vehicle scenario that is believed to precede many lane-change/merge crashes. Further research will be necessary to determine if improved geometric visibility is accompanied by improved detection of turn signals by viewing drivers, and whether improved detection of turn signals has important safety implications. |
Dynamic Element Analysis | A new formulation for dynamic analysis of the response of vibro-acoustic systems is developed. The method is based on a discrete element formulation similar in geometry to a finite element model. However, the Dynamic Element Analysis uses transcendental functions for the response interpolation functions. The phase of the functions converges at high frequencies to the Statistical Phase. At low frequencies the interpolation functions converge to the polynomials used in finite elements. Thus, the Dynamic Element Analysis covers a wide frequency range without requiring a refinement of the mesh, and it provides a deterministic response in the mid-frequency range before converging to a statistically correct response at high frequencies. Examples are shown of the response of structures and acoustic radiation. |
Lessons Learned Through Working With General Motors | In many companies and corporations, a number of very good ideas never reach fruition, even after a substantial investment in time and money. Can corporations afford to squander such assets…or is it a result many other forces and variables that inadvertently conspire to failure? The Vibration Advisor Expert System is one of these great ideas with a significant amount of time and money invested and a proven functionality that didn't make it. This paper will describe the project and offer for discussion and thought, some of the reasons for implementation failure. It was the right tool at the right time - but it did not benefit the Corporation. |
Measurement of Sound Impulses Due to Airbag Deployment in a Standardized Enclosure | The consistent measurement of airbag deployment noise places special demands on the enclosure in which the measurements are performed. The acoustical characteristics of the enclosure must be stable over long periods. It must also be sufficiently robust to withstand the loads involved. The use of a standardized enclosure provides a uniform basis for comparable measurements in different laboratories. The reasons for selecting a specific small cabin as the standard enclosure are discussed in this paper. Some examples of tests performed in the small cabin with a wide range of airbag systems are presented. High-speed film recordings of the deployment of the airbags were made simultaneously with the acoustic measurements. The stability of the acoustic environment and of the enclosure were important factors in obtaining reliable and comparable results. |
Road Noise Reduction Using a Source Decomposition and Noise Path Analysis | It is considered that improper usage of rubber bushes and weak dynamic characteristics of chassis and body structures yield interior road noise problems. This paper describes systematic processes for road noise improvement along with measurement and analysis process. Firstly, the noise sources are identified by using a source decomposition method. Secondly, the main noise paths are identified by using a noise path analysis (NPA) method. Thirdly, the design modification of body panels is suggested for road noise reduction by using a panel contribution analysis. Finally the method is validated by applying to road noise improvement process for a new vehicle. |
A Study on the Development Process of a Body with High Stiffness | Design optimization of a vehicle is required to increase a product value for noise and vibration performances and for a fuel-efficient car. This paper describes the development process of a high stiffness and lightweight vehicle. A parameter study is carried out at the initial stage of design using the mother car, and a design guide with a good performance is achieved early prior to the development of the proto car. Influences of body stiffness based on the relative weight ratio of the floor and side structures are analyzed. Results show that bending and torsional stiffness has a significant effect on weight distribution ratio. Influences of the distribution of side joint stiffness are analyzed through numerical experiments. Results reveal that the stiffness difference between the upper and lower parts should be small to increase the stiffness of a body. In addition, the process of designing the body attachment stiffness is summarized to ensure the vibration isolation of the suspension mounting unit. In the case of the rear suspension mounting unit, the body attachment stiffness is found to increase in the left and right direction, when the package tray pass-through structure is used on the rear wheel housing and rear floor joint, to minimize rear seat noise. This paper is expected to shorten the development period by the present stiffness analysis process. And a body with high stiffness and lightweight is developed for the vibration and noise performance at the initial stage of design. |
Statistical Energy Analysis of a Fuel Cell Vehicle | In this paper the application of Statistical Energy Analysis (SEA) to the sound package design for a fuel cell powered sedan is presented. Fuel cell vehicles represent a different challenge to a vehicle with a conventional powertrain. With the replacement of the internal combustion engine (ICE), a principal source of airborne and structure-borne powertrain noise, the expectation is that the cabin noise levels would be significantly reduced as the main noise sources would be road and wind noise. A fuel cell powertrain, however, has a number of mechanical sources on the body structure that will radiate airborne noise and may transmit significant structure-borne noise to the vehicle interior. With this alternative power train, much of the conventional wisdom on vehicle sound package developed from experience with ICE's must be reconsidered. Utilizing an SEA model, the paper discusses the unique problems encountered in designing a noise control package for a fuel cell-based vehicle, the packaging design issues related to space, weight and design restrictions, and presents some initial correlation results. It is concluded that an SEA model can be used to provide design recommendations on the high frequency NVH performance of the vehicle structure. |
Development of a New Standard for Measurement of Impulse Noise Associated With Automotive Inflatable Devices | The SAE Recommended Practice for measuring impulse noise from airbags, SAE J247, “Instrumentation for Measuring Acoustic Impulses within Vehicles”, was first published in 1971 and last affirmed in 1987. Many advances have occurred in understanding and technology since that time. Work in the automotive industry to investigate the characteristics of noise from airbag deployments has shown that large components of low frequency noise can be present when an airbag deploys in a closed vehicle. Others have shown that this low frequency noise can have a protective effect on the ear. Likewise, work for many years at the US Army Research Lab has investigated the risk of hearing loss for a human subjected to an acoustic impulse. That research led to the creation and validation of a mathematical model of the human ear, called Auditory Hazard Assessment Algorithm - Human (AHAAH). In 1998, the SAE Impulse Noise Task Force (INTF) of the Inflatable Restraint Standards Committee performed a series of experiments to help understand the predictions of the AHAAH model. This work compared in-vehicle test results with those obtained from an acoustic reverberation chamber. These tests used a method published by a German Airbag Consortium called the AK-ZV Working Committee and documented in report AK-ZV01. Much of this work was summarized in SAE J2531, an Information Report developed by the SAE Impulse Noise Task Force, documenting the state-of-knowledge in 2003. Also in 2003, Banglmaier and Rouhana reported on the results of over 100 tests performed to help clarify test conditions for the assessment of noise-induced hearing loss (NIHL). Based on all of this information, a new revision of SAE J247 has been drafted and is in the process of committee editing. This paper describes the changes made to SAE J247 and the rationale for those changes. |
Application of Statistical Noise Generation and Radiation for Aeroacoustic Predictions in the Automotive Industry | Flow-induced noise is an important issue in the automotive industry. TNO in cooperation with AVL developed an efficient hybrid Computational AeroAcoustics (CAA) method, aimed at actual engineering applications, i.e. fast, robust, accurate and able to handle highly complex geometries. The hybrid method is based on standard Reynolds Averaged Navier-Stokes solution of the flow field under consideration, and combines an Statistical Noise Generation and Radiation (SNGR) technique to generate a time-accurate realization of the turbulence and a high order, quadrature-free discontinuous Galerkin - Linearized Euler Equation (LEE) solver to predict the propagation of the acoustic waves. Owing to the unstructured grid strategy the present approach is both particularly well suited for the complex geometries common to car design as well as sufficiently flexible in selecting acoustically interesting subdomains. This paper demonstrates the capabilities of the CAA method in two cases on the noise induced by the flow around a car, and more specifically, by the A-pillar and rear-view mirror on the side window. |
Xtreme Make-Over In 24 Hours | Our conference chairman told me that this special technical section was structured to provide “some words of wisdom from the old guys” or something to that effect. I know I can meet most of his requirements. I am a pensioner and an oak tree. However, “words of wisdom” maybe a challenge. Solving noise problems, setting acoustical performance targets and guidelines, and developing noise control systems for new and carry-over vehicles can be very challenging and time consuming particularly in today's culture. In the 1970's and 80's, and 90's we had the same challenges. Our customers demanded and appreciated a quiet vehicle. They want to talk to each other without shouting or to enjoy a favorite music selection regardless of weather, road conditions, or vehicle speed. The use of ear plugs or cotton is not acceptable! Noise Gremlins (Figure 1) can ruin a good day! Management, on the other hand, reasonably requires that we accomplish all of these objectives as soon as possible (yesterday preferred), don't spend any money, design it for easy assembly and above all keep-the-lead-out! Don't add any weight to the vehicle! Did your boss make any of these demands recently? |
A Study of NVH Vehicle Testing Variability | At certain key stages in the vehicle development process, prototype vehicles are available for NVH testing. This testing fulfills two functions: primarily it is used to assess the status of the vehicle to the program NVH performance targets, but it also provides an opportunity to validate the vehicle SEA model. These single vehicle test events provide a snapshot of the NVH performance but do not provide any understanding of the variability of the NVH performance, which is due to many factors: components, build or assembly and test setup variability. SEA models can be used to estimate the vehicle level variability, if the variability of the interior components is understood, but there is limited data available to confirm the accuracy of these predictions. In this paper we examine the repeatability and reproducibility through a standard gage R&R study of Engine Noise Reduction (engine NR) and Tire NR testing. We also examine the variation in NR from vehicle-to-vehicle through testing on six compact sedans of the same vehicle line. A more limited chassis dynamometer study on three of the six vehicles is also presented to look at typical running vehicle measures such as articulation index, loudness and overall SPL for tire and powertrain noise. Although the sample population is small, we have extracted estimates of variation in body noise reduction due to test setup, actual component and build variation and the implications for predicting variability through SEA models. |
Electromagnetic Compatibility of Direct Current Motors in an Automobile Environment | As the volume and complexity of electronics increases in automobiles, so does the complexity of the electromagnetic relationship between systems. The reliability and functionality of electronic systems in automobiles can be affected by noise sources such as direct current (DC) motors. A typical automobile has 25 to 100+ DC motors performing different tasks. This paper investigates the noise environment due to DC motors found in automobiles and the requirements that automobile manufacturers impose to suppress RF electromagnetic noise and conducted transients. |
CAE Virtual Test of Air Intake Manifolds Using Coupled Vibration and Pressure Pulsation Loads | A coupled vibration and pressure loading procedure has been developed to perform a CAE virtual test for engine air intake manifolds. The CAE virtual test simulates the same physical test configuration and environments, such as the base acceleration vibration excitation and pressure pulsation loads, as well as temperature conditions, for design validation (DV) test of air intake manifolds. The original vibration and pressure load data, measured with respect to the engine speed rpm, are first converted to their respective vibration and pressure power spectrum density (PSD) profiles in frequency domain, based on the duty cycle specification. The final accelerated vibration excitation and pressure PSD load profiles for design validation are derived based on the key life test (KLT) duration and reliability requirements, using the equivalent fatigue damage technique. The coupled vibration and pressure simulation is then implemented by applying both the base acceleration and pressure pulsation loads to the manifold CAE model, in terms of PSD functions, using the frequency response analysis technique. The computer simulation generates dynamic response of the air intake manifold structure, in terms of stress PSD results at identified hotspot locations. The durability life of the air intake manifold design is then evaluated based on the simulated stress and material fatigue damage model. The fatigue damage model is established from fatigue data of the manifold material obtained at different test temperatures. The presented procedure has helped the engineering team to identify potential durability design problems without a prototype, and to guide the design changes and modifications. It has shown that CAE virtual tests provide a way to speed up air intake manifold product development, and to minimize prototypes and costs. |
Development of the Vibrational EFA (Energy Flow Analysis) Software EFADSC++ R4 and its Applications to Automobiles | The Energy Flow Analysis (EFA) offers very promising results in predicting the noise and vibration responses of system structures in medium-to-high frequency ranges. We have developed the Energy Flow Finite Element Method (EFFEM) based software, EFADS C++ R4, for the vibration analysis. The software can analyze the built-up structures composed of beam, plate, spring-damper, rigid body elements and so on, and has many useful functions. For the effectiveness and convenience of software, the main functions of the whole software are modularized into translator, model-converter, and solver. The translator module makes it possible to use of finite element (FE) model for the vibration analysis at low frequencies. The model-converter module changes FE model into energy flow finite element (EFFE) model. It is generates joint elements to cover the vibrational attenuation in the complex structures composed of various elements and can solve the joint element equations by using the wave transmission approach very quickly. The solver module supports the various direct and iterative solvers for multi-DOF structures. EFADS C++ R4 can also use the analytic parameters input by user. The simulation about the local part of real automobile is performed sucessfully. |
Diagnostics of Engine Noise During Run-up Using HELS Based Nearfield Acoustical Holography | This paper describes the diagnostics of noise sources and characteristics of a full-size gasoline engine during its run-up using Helmholtz Equation Least Squares (HELS) method based nearfield acoustical holography (NAH). The acoustic pressures are measured using an array of 56 microphones conformal to the contours of engine surfaces at very close range. Measurements are collected near the oil pan, front and intake sides. The data thus collected are taken as input to HELS program, and the acoustic pressure mappings on the oil pan, front and intake surfaces are calculated. These reconstructed acoustic quantities clearly demonstrate the “hot spots” of sound pressures generated by this gasoline engine during its run-up and under a constant speed condition. These acoustic pressure mappings together with order-tracking spectrograms allow for identification of the peak amplitudes of acoustic pressures on a targeted surface as a function of the frequency and engine rpm. This information enables one to correlate a particular drive train order at a specific frequency and rpm to the peak amplitude of the sound pressure at a specific location on the engine surface, e.g., an oil pan. The depth and breadth of clearly defined information obtained can be very helpful to identify noise sources and how they change with the engine speed. |
The Effects of Body Joint Designs on Liftgate Chucking Performance | Liftgate chucking is one of the major squeak and rattle concerns for vehicles with a large body closure opening in the liftgate area. High frequency chucking noise is generated as a result of the contact between the latch and striker of a liftgate. Traditionally, liftgate chucking problems (if present) are found and fixed by using a more robust latch/striker mechanism at a very late design stage that normally results in cost penalties for vehicle programs. Significant effort has been made at Ford in identifying and clarifying up-front drivers or body performance metrics that predominantly influence downstream squeak and rattle sensitivity. Two key body performance metrics (diagonal distortions at the liftgate opening and relative displacement between the latch and striker of a liftgate) are found to affect liftgate chucking sensitivity. The effects of body joint designs on liftgate chucking performance are discussed using these metrics in CAE analyses. A joint design that balances performance, weight and cost is identified in the process. |
On the Relation Between Exposure to Sound and Auditory Performance | This paper presents the results of 10 years of work on the relation between exposure to sound and its effect on hearing. More than ten thousand persons were examined. Highlights of the results are: (a) a person's everyday exposure to sound can have a beneficial effect on hearing such as reducing the effect of aging and lowering the susceptibility to damage; (b) women are more susceptible to low-frequency noise than men; (c) impulsive sound is particularly dangerous to hearing; (d) three different resonances appear to cause most damage after being exposed to intense impulsive sound; and (e) there is a strong relation between the structure of impulsive sound and damage to hearing. With regard to the effect of the peak sound pressure from airbag deployment, driver airbags are less damaging to the ears than firearms because of masking effects. |
An EFEM0-SEA Integrated Model of a Trimmed Van | High frequency responses of structural-acoustic systems may be predicted by statistical energy analysis (SEA) or energy finite element method (EFEM). To combine the good features of these two techniques, a simplified energy finite element method, referred to as EFEM0, has been developed recently. The EFEM0 technique, which is compatible with SEA, integrates the joint coupling procedures for discontinuous systems and the finite volume formulation for continuous system. The EFEM0 models have been verified either analytically or experimentally for one- and multi-dimensional systems. In this study, the EFEM0 technique is applied to a passenger van for a noise control investigation. The general scheme is to incorporate the EFEM0 coupling factors into a SEA model in order to release some SEA assumptions and improve the SEA model, especially for relatively high damping, strong coupling and direct field cases. The EFEM0-SEA integrated model for the trimmed van is validated by experimental data. Several noise control strategies will be discussed for the integrated model to optimize the sound package. |
Sound Package Design for a Convertible by Statistical Energy Analysis | The application of SEA (Statistical Energy Analysis) to the sound package design for a convertible is presented. SEA modeling was used optimize the soft-top construction and the acoustic insulation in the top-stack area (where the soft-top is stored) which were shown to be important transmission paths for tire noise. Correlation between measurement data and predictions from the SEA model is presented and good agreement shown. It is concluded that SEA can be applied to determine the special sound package requirements for convertible vehicles. |
Novel Design of a Multi-Function Acoustics Laboratory for the Testing and Evaluation of Automotive Acoustics Systems and Components | The acoustic performance requirements of vehicle interior trim elements and sound package elements have increased significantly in recent years. Additionally, the burden of developing these products has been shifted from the Original Equipment Manufacturers (OEMs) to suppliers. To aid in developing lightweight, low cost, and high performance parts, a flexible acoustic testing facility was designed for use in many different applications. Specific, purpose-built chambers for only one type of measurement are typically not cost effective facilities. |
Towards a Standard for Material Friction Pair Testing to Reduce Automotive Squeaks | Today vehicle owners perceive squeaks and itches inside a vehicle cabin as a major negative indicator of vehicle build quality and durability. Manufacturers struggle to bear the high costs of squeak and rattle (S&R) related warranty. Although the benefits of structural integrity and tight manufacturing tolerances with respect to the prevention of S&R are known, today's cost, weight, crash requirements, aesthetic demands and environmental/fire hazard rules quite often dictate the design of S&R prone sub-systems. Even sub-systems with the best possible structural design and manufacturing tolerances are not immune to extreme environmental conditions, and mating materials can initiate contact leading to S&R. One method of minimizing the possibility of squeaks is by the judicious selection of mating material pairs. This paper describes a test process aimed at the quantification of material pair compatibility. Also described is a state of the art, flexure-based (virtually frictionless) test instrument that has been developed for such material pair compatibility studies. A group of 17 material pairs with known historical problems were identified by experienced automotive designers and were put through 374 tests encompassing several realistic temperature and humidity extremes in a complex test matrix. Material pair samples were “rubbed together” in an accurately controlled manner. The types of relative displacement that were used were single excursion pull and realistic road inputs in the form of a shaped random profile. The material pairs included combinations of PVC, ABS, TPO, PP and painted metal from sub-systems such as instrument panels, center consoles, body panels, door trim and weather-strips. Instationary Zwicker loudness was used as a metric for quantifying the squeak in addition to classical friction parameters. From the test data, a classification of the material pairs was made pertaining to their propensity to generate squeak and itch (S&I). Initial levels of correlation with GM material experts' classifications of the same pairs are promising and are the motivation for further studies. The Team (Defiance, GM and MB Dynamics) feels strongly about the need for a comprehensive materials database that is the result of a uniform experimental procedure to identify pertinent material characteristics in order to understand, verify and significantly reduce stick-slip in automotive applications. The Team feels that the test equipment, test procedures and analysis methods that were developed during this project and that are described in this paper, greatly contribute towards this cause. The Team wants to extend the invitation to other interested parties (tribology researchers, scientists, automotive or other engineers), to bundle efforts, share best practices and lessons learned, and work towards a standard for material friction pair testing. |
Design of a World-Class Vehicle Acoustical Laboratory Facility | This paper examines the critical design elements and issues associated with converting facility goals and business objectives into a functional facility. The design of the General Motors Noise and Vibration Analysis Laboratory (NVAL) will be discussed to help clarify key points. A team-oriented design approach is essential to meet the stringent safety, flexibility and operational requirements associated with noise, vibration and harshness (NVH) facilities. The first step is establishing the design team and their respective roles in the process. The challenge of “how to build a facility that meets the specified objectives” is addressed in the programming phase. Operational and financial objectives are reviewed and validated. Upon completion of the programming effort, the team attacks the special technical challenges borne out of that process. This is the beginning of the design development phase of the project and involves tackling such issues as acoustic isolation, vibration isolation and HVAC system noise control. The goal is to meet the technical challenges associated with actual facility capabilities and simultaneous testing of different operations within the building. At the conclusion of these critical elements, the design team is prepared to complete the detailed design of the facility and plan for the ensuing construction.(1) This paper offers a summary of the NVH facility design process, as well as key items learned through the course of the GM NVAL design effort. |
Development of Windshield Defogging | South America is traditionally a follow source region where vehicles are mostly developed and validated in the lead development regions with the goal of having a single design applied globally. Most of these developments are proven efficient, which is the case of air conditioning systems, however heating and ventilation systems have particular regional requirements according to details suggested at this paper where we explore regional needs (tropical climate condition) and unique development specifications for windshield defogging. |
Wavelet-Based Visualization of Impulsive and Transient Sounds in Stationary Background Noise | Scalograms based on shift-invariant orthonormal wavelet transforms can be used to analyze impulsive and transient sounds in the presence of more stationary sound backgrounds, such as wind noise or drivetrain noise. The visual threshold of detection for impulsive features on the scalogram (signal energy content vs. time and frequency,) is shown to be similar to the audible threshold of detection of the human auditory system for the corresponding impulsive sounds. Two examples of impulsive sounds in a realistic automotive sound background are presented: automotive interior rattle in a vehicle passenger compartment, and spark knock recorded in an engine compartment. |
Validation and Improvement of Body Panels FE Models from 3D-Shape and Vibration Measurements by Optical Methods | In this paper, we propose a strategy for validation and improvement of structural finite elements (FE) models using vibration and 3D-shape optical measuring method. The main advantage of these methods is to provide a whole field information allowing to speed-up the measurements, combined with an high spatial resolution ensuring updating quality. This strategy is especially adapted to the improvement of light weight body panel structures. Several application examples are presented. |
Evaluation of Wind Noise Sources Using Experimental and Computational Methods | Experiment and CFD have been performed to clarify the distribution of wind noise sources and its generation mechanism for a production vehicle. Three noise source identification techniques were applied to measure the wind noise sources from the outside and inside of vehicle. The relation between these noise sources and the interior noise was investigated by modifying the specification of underbody and front-pillar. In addition, CFD was preformed to predict the noise sources and clarify its generation mechanism. The noise sources obtained by simulation show good agreement with experiment in the region of side window and underbody. |
Electromagnetic Compliance Issues of Project Oculus | Project Oculus, an experimental configurable sensor platform for deploying airborne sensors on a C-130 aircraft, is currently in its pre-flight testing phase. The electronics driving the platform are available commercially off the shelf (COTS) and as such are not automatically rated to comply with stringent military electromagnetic standards as defined in MIL-STD-461. These COTS electronics include efficient switching power converters, variable frequency motor drives (VFD), and microprocessor based equipment, all of which can present electromagnetic interference (EMI) issues. Even in a design where EMI issues were not considered up front, it is often possible to bring the overall configuration into compliance. Switching and digital clock signals produce both conducted and radiated noise emissions. Long cable runs and enclosure apertures become noise transmitting antennas. Large switching currents place noise on the power lines causing interference with other equipment. These problems became apparent during initial EMI compliance testing. This publication will outline the shielding and filtering techniques used to resolve these problems in preparation for flight testing and evaluation. |
University of Idaho's Clean Snowmobile Design Using a Direct-Injection Two-Stroke | The University of Idaho's entry into the 2005 SAE Clean Snowmobile Challenge (CSC) was a second-generation gasoline direct-injection (GDI) two-stroke powered snowmobile. A battery-less direct-injection system was used to decrease exhaust emissions and improve fuel economy without reducing the power output of the engine. A spiral exhaust silencer was used to reduce exhaust noise. Under-hood noise was targeted by using sound absorbing materials and a sealed hood. Chassis noise was addressed by using a spray-on rubberized material that absorbs vibrations transferred through the chassis. Power transfer and space issues were addressed with the addition of a direct-drive system that eliminated the jackshaft. The snowmobile entered into the 2005 SAE CSC competition was lightweight, fun-to-ride, powerful, and had reduced exhaust emissions. |
Active Noise Control Simulation in a Passenger Car Cabin Using Finite Element Modeling | According to the importance of Active Noise Control (ANC) in 3D spaces such as vehicle cabins for reducing unwanted noises inside cabins, the purpose of this paper is to demonstrate the finite element (FE) modeling, simulation and analysis of an ANC in a 3D acoustic passenger car cabin with filtered-X LMS adaptive feed forward controller. For this purpose, after creating an acoustic FE model of the passenger car cabin and calculating its resonance frequencies and mode shapes; several transfer functions of primary, secondary and feedback paths of the acoustic field is estimated in digital domain in accordance with frequency responses obtained from FE model in order to simulate the behavior of ANC system. In all simulations, acoustic feedback effect is considered and the acoustic feedback neutralization technique is used to reduce or overcome the instability potential of this effect. The performance of different configurations of multi-channel “FXLMS” ANC systems is studied with “off-line” modeling technique using Finite Impulse Response (FIR) filters. The obtained results are useful for optimal placement of secondary sources and error microphones. It is found that, the acoustic pressure attenuation inside cabin can be significantly reduced if the control source is placed in close proximity to the reference microphone. However, increasing the number of sensors and/or the number of control sources located remotely from the primary source, have little impact on the maximum achievable reduction in the acoustic pressure in the cavity. |
Productive measurement of transmission loss characteristics using Nearfield Acoustic Holography | A continuously growing demand comes from the automotive industry for optimisation of materials and sound insulating products implementation inside the car, in order to propose the best acoustic performance at reduced costs. As already presented last year at SEA Brazil [9], the approach based on extensive use of the acoustical holography system dBVISION of 01dB-METRAVIB provides part of the solution to such a demand. Whereas the first paper was dedicated to some general considerations and practical aspects of NAH implementation inside a car, the one proposed for the 2005 session is focused on a very important aspect of NAH measurements, namely productivity, for both inside and outside measurements. The paper reviews the NAH technique advantages for measuring the acoustic field inside and outside a vehicle and performing extensive studies on transmission loss characteristics of panels and car openings, with the aim of: detailed localization of possible acoustic weakness points on single components, ranking of the tested components in terms of global and partial radiated power contribution driving possible optimisation of component in the early stages of the design cycle The applied test set-up will be presented and its main features regarding productivity improvement will be highlighted, with a special attention to the compact and versatile robotized instrumentation used for this type of measurements. The presentation will be illustrated by operational results in different situations and some possible extension will be proposed in order to open this technique to the efficient characterization of 3D-shaped structures. |
Reference vs. Preference: The “Surround” of Surround Sound | Surround sound provided by stereo and 5.1 systems may not be satisfying all its listeners. Whether in the automobile or in the home, customers complain of “nothing from the rear speakers”, or about the sound “not filing the room”, etc. While 5.1 systems promise more surround, the economics of music production and concerns of music professionals are likely causing stereo to dominate production resources and causing 5.1 mixes to miss their full potential. The author believes that post-processing electronic and acoustic manipulation can produce sound that customers will prefer. A controlled experiment was performed which compared reference stereo and surround systems to ones augmented by extra surround equipment. This paper: 1 Discusses a very brief history of stereo and surround sound 2 Describes an experiment used to test listener preference, 3 Details experimental results when comparing reference-like music presentation with envelopment enhancing sound processing using both stereo and 5.1 recorded music. |
Application of Novel Viscoelastic Microcellular Foams for Passive Noise Control in Automotive Body Structures | This paper discusses the development of lighter weight, superior acoustic performance and cost effective viscoelastic microcellular foams for the use in automotive passive noise control panels. The study incorporates the control of the foaming process for production of variable microcellular structures and morphologies for the novel foams under investigation. For that purpose, the foaming process was controlled for production of foam samples with various microcellular structures. Cross linked LDPE was used as a base material for the produced foams. Very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9E108 - 1.6E109 cells/cm3) and desired expansion ratios (3 - 9 folds) were successfully obtained. While the material is overly porous, it is noted that the unfoamed skins on the outer surfaces of the samples have prevented sound waves from penetrating the samples. Manual skin removal resulted in slight improvement in sound absorption testing. However, in order to get more reliable data, skinless samples need to be produced. |
Creation of a Brake Development City Traffic Vehicle Test in Shanghai / Suzhou, China | As automotive manufacturing increases in China, boosting the sales of OEM and aftermarket brake system components, it becomes increasingly important to address customer and manufacturer concerns regarding the implementation of localized testing. In response to the growing demand to understand noise and component wear characteristics, research to assess representative city traffic patterns in the city and suburbs of Shanghai/Suzhou, China has been conducted. With this data, a procedure for operating a city traffic vehicle test in China has been developed and documented in this paper. This testing process provides data that quantifies lining and rotor wear, brake energy levels, lining temperatures, component NVH, and other brake system qualities. Through the standardization of this procedure, OEM suppliers, aftermarket vendors, and other interested parties will have the means necessary to execute controlled and standardized vehicle level brake testing which generates data for the purposes of predicting brake wear and noise performance. |
Noise Suppression chips in Small Motors | Expanding the applied frequency bandwidth to include higher frequencies of conducted and radiated electromagnetic interference (EMI), has brought all inductive devices including the small sub-fractional motor to the attention of vehicle manufacturers5. The surface mounted noise cancellation chip can be combined with design strategies to reduce, contain, and attenuate the natural occurring broadband EMI phenomenon in the permanent magnet direct current motor. |
Optimization Study for Sunroof Buffeting Reduction | This paper presents the results of optimization study for sunroof buffeting reduction using CFD technology. For an early prototype vehicle as a baseline model in this study a high level of sunroof buffeting 133dB has been found. The CFD simulation shows that the buffeting noise can be reduced by installing a wind deflector at its optimal angle 40 degrees from the upward vertical line. Further optimization study demonstrates that the buffeting peak SPL can be reduced to 97dB if the sunroof glass moves to its optimal position, 50% of the total length of the sunroof from the front edge. For any other vehicles, the optimization procedure is the same to get the optimal parameters. On the other hand, however, this optimization study is only based on fluid dynamics principle without considering manufacturability, styling, cost, etc. Further work is needed to utilize the results in the production design. |
Crew Protection, Contingency EVA and the Crew Exploration Vehicle | The proposed NASA Crew Exploration Vehicle (CEV) has been labeled “not as a repetition of Apollo, but instead what Apollo should have been.” While this designation is certainly ripe for debate, there is no debating that the space suit community has, up to this point, had limited or no input into the on-going design of the CEV. However, it is important that the community take the opportunity to influence the configuration of the proposed CEV so as to optimize its orbital and planetary/lunar EVA capability, flexibility and safety. This “window of opportunity” will not remain open for long, as the CEV’s configuration is rapidly congealing. This paper covers: 1. Brief space suit configurations, employment and history. 2. Brief descriptions and comparisons of IVA, EVA and IEVA space suits. 3. How history can be a guide to optimize EVA for the Crew Exploration Vehicle. |
System Dynamics and Ride Quality Assessment of Automobile | Ride quality analysis involves the study of three topics: ride excitation sources, system dynamics of a vehicle, human perception and tolerance of vibration. In this study, we establish an integration analysis procedure including the system dynamics analysis and the ride quality evaluation. The dynamic responseof a passenger car was simulated by a multi-body model with ADAMS software. The calculated acceleration responses of seats coincide with the field measured ones. The effect of damping ratio (C), stiffness coefficient (K), vehicle speed and seating location on the acceleration response are also investigated. The ride quality analysis was conducted following the ISO 2631 standard. A LabVIEW computer code was developed to provide fast and convenient assessment of the comfort. A 3-axis translational accelerometer was installed on the seat. The responses of a passenger car traveling on the long wave road, asphalt uneven road and stepped joint road of proving ground in ARTC (Automotive Research & Testing Center in Taiwan) were collected. A satisfactory agreement was observed between the comfort index obtained on the experimental data and dynamic simulation. |
Development of a Lightweight Sound Package for 2006 Brand-New Vehicle Categorized as C | This paper describes an effective method of developing a soundproof package, which balances both light weight and high noise insulation performance. Since it is required to propose design of sound insulator in the early stages of the development, the hybrid statistical energy analysis (SEA) modeling method is applied, which is practical for high frequency analysis. Also an acoustic characteristic estimation technique of the multi layer structures is used. As a result of applying these effective methods, the 2006 brand-new vehicle categorized as C has enhanced in road noise quietness and decreased in weight as compared with the previous model. |
The Armageddon Device Part II | Applying good engineering practices to software-intense automotive systems can save automakers millions of dollars in warrantee costs, lost customer loyalty and lawsuits. Carefully crafted development testing could expose non-robust software that fails intermittently when the customer activates the function. The chances are very good the service technician will replace the ECU when the customer brings the vehicle in for repair of the intermittent behavior. These electronic parts are sent to the supplier for analysis. Upwards of 60% of all ECUs analyzed are TNI (Trouble Not Identified) related. This paper elaborates on a method of developmental testing that provides these cost savings. This paper continues to build on concepts discussed in the SAE paper, “The Bus Crusher and The Armageddon Device Part I”. [1] The experiment of subjecting an ECU to several electrical disturbances is explained in detail. The objective of an embedded system is to have a predictable output for any combination of input sequences. If the operation of the embedded system is viewed as a big state diagram, testing verifies that the embedded system operates in acceptable states and that transitions between states are all known and predictable. The stress-testing concept described in this paper generates sequences of stimuli that can’t normally be planned for (the number of combinations is massive). The embedded system must always remain in a known acceptable state, regardless of the stimulus. The testing techniques described allows for the creation of a stimulus to verify the robustness of the embedded system. Experiments were conducted on electrical breadboards, which were subjected to RF (Radio Frequency) noise, periodic network initialization, communication bus failures, intermittent ground open, and repeated cycling of the locking function. The hypothesis of the experiment was to stress the ECU’s operating environment by causing events that seldom occur, and make them happen with high regularity. The electrical noise level is below the ECU design limit, e.g., the task monitoring the ECU voltage range will ignore voltage drops of less than 15 msec (milliseconds). Subjecting the ground circuit to an interruption of less than 15 msec should result in no humanly perceivable behavior change. Methods to stress the software are the focus of this document. Described are: 1. Building the RF Blaster 2. Building the Armageddon Breakout box 3. Introducing new noise factors; ground lift and periodic network initialization 4. Lock-Unlock Cycle test 5. Results of the tests |
Investigation of the perceived sound quality of an automotive HVAC system | The noise emitted by the heating, ventilation and air conditioning system (HVAC) has a great influence on the car acoustical comfort and quality perception. To improve its sound quality, physical properties which determine the subjective perception have to be identified. The HVAC-noise of twelve cars in different arrangements of fan speed and direction of air flow was recorded for later objective and subjective analysis. All cars were of the same model, but with three different types of HVAC-systems, and had just been manufactured. Objective analysis with sound quality software and subjective evaluations was carried out. Using multiple linear regressions on the subjective data, relations between subjective results and psychoacoustic metrics were determined and models to predict subjective response to HVAC sounds are proposed. It is shown that the annoyance caused by the HVAC-noise can be satisfactorily described by Zwicker's stationary loudness model. |
In-Vehicle Panoramic Noise Source Mapping | For many years engineers in the automotive market have struggled to find ways to accurately and efficiently map the noise sources found inside a vehicle. Many techniques, both theoretical and measurement based, have been proposed and used, but there has always been a trade off between accuracy and efficiency. Techniques like sound intensity mapping and Statistical Energy Analysis have proven to be accurate when mapping noise sources in vehicle, but require a large investment in time and money to create a simple, easy to interpret picture showing where dominant noise sources come from. In this paper the authors will introduce and demonstrate a novel technique, spherical beamforming, which can overcome the issue of test time and produce fast, accurate noise maps from the interior of a vehicle. |
Investigation on the Acoustic Performance of Current Trunk Load Floor Solutions | Different solutions for trunk floors recently presented on the market have been collated and investigated in order to better define the possible features integrated and the acoustic performance of trunk load floors. A description protocol has been devised and applied to systematically categorize the whole set of features potentially characterizing a trunk floor, and the wide range of solutions used with respect to materials, processes and design configurations. The acoustic performance has been specifically addressed with the evaluation of the acoustic absorption on both sides and a specific testing procedure to evaluate the noise insulation capability provided by actual parts. The results of the actual parts acoustic performance measurement campaign show that a substantial improvement in the acoustic function of the trunk floor module can be achieved by the systematic choice of materials, processes, and of the geometry of the part, in compliance with the standard OEMs requirements Some solution trends for vehicle architecture and segment are highlighted, and recommendations to enhance the acoustic performance and the functionality of trunk floors are provided. |
FEA Design of a Vibration Barrier to Reduce Structure Borne Noise | In the low frequency range, mechanical vibrations propagate into the car body by structure borne transmission. In order to limit this transmission, an original system called “Vibration Barrier” has been developed. It reduces the vibrations propagating into the hollow body network (the transmission path) using a cavity part and the high damping foam technology. This paper describes the general concept and the FEA design process of a Vibration Barrier part. An example is given for a full car body. The best compromise of the tested designs leads to a significant reduction of the structure borne noise using a lightweight part. |
Combining an Energy Boundary Element with an Energy Finite Element Analysis for Airborne Noise Simulations | The Energy Boundary Element Analysis (EBEA) has been utilized in the past for computing the exterior acoustic field at high frequencies (above ∼400Hz) around vehicle structures and numerical results have been compared successfully to test data [1, 2 and 3]. The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration of complex structures at high frequencies and validations have been presented in previous publications [4, 5]. In this paper the EBEA is utilized for computing the acoustic field around a vehicle structure due to external acoustic noise sources. The computed exterior acoustic field comprises the excitation for the EFEA analysis. Appropriate loading functions have been developed for representing the exterior acoustic loading in the EFEA simulations, and a formulation has been developed for considering the acoustic treatment applied on the interior side of structural panels. In order to demonstrate how the new developments can be combined in airborne noise applications, a case study is presented. |
Tire Noise Reduction with Fiber Exterior Wheel Arch Liners | Tire noise reduction was evaluated with acoustically designed exterior wheel arch liners. The wheel liners were made with a fiber blend selected to meet acoustical requirements, process demands, and durability challenges. Fiber liners were installed in a vehicle and noise level measurements were made under a range of operating conditions. The results show the reduction in tire noise that can be achieved at the source and in the vehicle. A critical part of this evaluation was a rapid analysis technique to select metrics that correlated with subjective assessments. The analysis techniques also helped quantify the improvements over a baseline condition. |
Microcellular Ceramic Foams: Manufacturing and Study of Acoustical Properties | A novel processing method for fabricating high porosity microcellular ceramic foams for sound absorption applications has been developed. The strategy for fabricating the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and that of the base elastomer, it was possible to adjust the porosity with a very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9 × 108 - 1.6 × 109 cells/cm3) and desired expansion ratios (3 - 6 folds). Sound absorption testing has been performed using ASTM C-384 standard test. The preliminary results show that ceramic foams are candidate sound absorption materials. |
Evolution of Fiber Felt Technologies and Composites Enhancing Vehicle Acoustics | For generations, fiber felt technologies have been used as a building block in the development of various absorbers and decoupler composites used for automotive acoustics. This development has led to a variety of felt components with increasing complexity in their differentiations. This paper will review the evolution of three generations of felt technologies. Generation 1 and 2 will discuss needled, resinated, and thermoplastic fibers bonded felts by comparing various performance indexes from physical parameters of raw materials, manufacturing processes, product applications and physical characterization along with acoustic properties. Generation 3 will introduce strategies, technologies, and approaches to further simplify the multitude of fiber felt innovations. |
Product Sound Quality of Vehicle Noise – A Permanent Challenge for NVH Measurement Technologies | Sound quality of vehicle is more and more an important product feature which significantly influences the perceived product quality. Over recent years, the broad variety of new models, which resulted in increased competition, has lead to rising customer demands with regard to NVH (Noise, Vibration and Harshness) aspects. Apart from the indispensable troubleshooting, the acoustic engineer's scope of work is extended to NVH design engineering. Thus, innovative, ambitious measurement technologies were developed to meet these new, challenging tasks and to maintain a competitive advantage. |
Calculations of Wind Tunnel Circuit Losses and Speed with Acoustic Foams | The GM Aerodynamics Laboratory (GMAL) was modified in 2001 to reduce the background noise level and provide a semi-anechoic test section for wind noise testing. The walls and ceiling of the test section were lined with acoustic foam and foam-filled turning vanes were installed in the corners. Portions of the wind tunnel circuit were also treated with fiberglass material covered by perforated sheet metal panels. High skin drag due to roughness of the foam surfaces, along with high blockage due to the large turning vanes, increased the wind tunnel circuit losses so that the maximum wind speed in the test section was reduced. The present study calculates the averaged total pressure losses at three locations to evaluate the reductions in skin drag and blockage from proposed modifications to the circuit, which were intended to increase the test section wind speed without compromising noise levels. The effect of foam roughness, characterized by measurement of the boundary layer displacement thickness, was incorporated into CFD models with effective-viscosity and inner-wall-log roughness models. The mathematical correlation of the reduction of total pressure loss with the increase of test section speed is presented to justify the proposed circuit modifications. The projected reduction in the circuit total pressure loss coefficient from 0.54 to 0.44 is in good agreement with the tests. |
Dynamic Door Component Test Methodology | This paper describes the development of a Dynamic Door Component Test Methodology (DDCTM) for side impact simulation. A feasibility study of the methodology was conducted using a MADYMO computer model by taking parameters such as door pre-crush, door-to-SID (Side Impact Dummy) contact velocity and the deceleration profile into consideration. The prove-out tests of this methodology was carried out on a dynamic sled test facility. The DDCTM has been validated for various carlines. In addition, various existing dynamic component test methods are reviewed. In our approach, a pre-crushed door, mounted on a sled, strikes a stationary SID at a pre-determined velocity. A programmable hydraulic decelerator is used to decelerate the sled to simulate the barrier/door deceleration pulse during door-to-SID contact period. This test procedure provides excellent correlation of the SID responses between the component test and the full-scale vehicle test. The DDCTM significantly reduces the time and resources required for developing improved side impact protection systems, including new door/trim, side air bag systems and padding material evaluation. This methodology has been applied to the development of the Ford Deploying Trim System. |
Glazing Effects of Door or Frame Deformations in Crashes | 1990 Geo Prism front door side tempered glass windows 3 mm thick were slowly bent, or shock loaded, to failure, with the glass clusters and fragments then found as large as 13 x 10 cm, weight to 42 grams, with some sharp points and slivers, and speed of release from the glazing surface of intermediate size pieces to 23 km/h. The fracture patterns of the tempered glass bent or shock loaded to failure were often oblique rather than perpendicular, in comparison to the patterns of an unloaded tempered glass broken by a locally applied sharp pointed object. This explains the sharpness and many lacerations of tempered glass shattered in road crashes, often under conditions of bending or shock loading of the edges of the glazing before it fails. Modification of Federal Motor Vehicle Safety Standard 205 to include fragment studies and laceration effects are suggested. |
Front and Side Brake Lights | Most applications in the ever-expanding automobile safety arena can be categorized in one of two ways: (a) accident prevention and (b) occupant protection. This is for accident prevention. With this application there will be 360 degree brake lights on a vehicle; two units mounted on the front of the vehicle below the vision of the operator, one on each side and a unit mounted on the right and one mounted on the left side of the vehicle in front of the front door and behind the front fender well (preferred location). All of the rear (red), front (blue), and both sides (blue) are energized to emit light 360 degrees when the brake system is applied. |
Seamless Passenger Side Air Bag Doors | Passenger side air bags have been rapidly accepted by the public for the protection they provide; however, in exchange, they have created an issue with fit and finish detracting from the harmony and flow-through styling presently in vogue in vehicles. With the current plethora of materials and processes used to manufacture separate passenger side air bag doors and the inability to build components to a line on line fit, attempts to tune all these factors is a lesson in frustration. In 1992, a design and development team from Textron, Chrysler, Dow, and Allied Signal were given the assignment of making the 1996 Voyager/Caravan the industies first fully integrated seamless passenger air bag (PAB) door. Several critical factors had to be addressed: 1) split seam appearance 2) pab deployment at all temperatures 3) instrument panel integrity 4) customer abuse 5) head impact 6) manufacturability 7) foam retention As a result of their effort, a padded surface instrument panel without any visible seams over the PAB, was implemented into production on the 1996 Chrysler Voyager and Plymouth Caravan models. A vinyl skin is cast with a preferentially weakened section to allow predictable tearing during air bag deployment. The shell is processed using conventional means to provide an instrument panel with a mid-mount PAB canister and an insert molded plastic/steel door that has no distinguishing features to indicate where the bag will deploy. This provides a seamless flow-through appearance, optimizing color, gloss, grain and dimensional match. |
Aerodynamic Simulations by Using Discontinuous Interface Grid and Solution Adaptive Grid Method | Aerodynamic simulations of automobiles with an airflow type rear spoiler (a spoiler that guides part of the flow on the roof onto the rear window of a one-box or two-box car to reduce the adhesion of snow or dust on the rear window) using a discontinuous interface grid method and around a rear view door mirror using a solution adaptive grid method are presented. These new methods have made it possible to capture the detail phenomena around equipment items such as spoilers and door mirrors, thereby improving the accuracy of the CFD (Computational Fluid Dynamics) simulations and shortening the time required. |
A Sound Quality System for Engineers | In the eighties, the main concern in the automotive industry from a designer's standpoint was a level issue. In the nineties, the market has put more stringent requirements on the automotive industry with respect to noise in general and psychoacoustics. The governments have imposed lower limits with respect to pass-by noise standards. Customers are spending more time in their car than in the past and are demanding acoustical comfort. All of this is leading to an environment where a sound quality system is becoming a daily tool in the design and trouble-shooting world. This paper describes what should be looked for in a sound, how to quantify these properties and what tools are needed. These steps are then applied in a case study. |
The Perfectly Silent Car - An Engineering Goal? | A look at the car development of today shows that even strictly cost oriented cars try to give their customers comfort and calm riding. High value cars explain themselves as a substitution for your home when you are on the road. Even from the environmental point of view, people, governments and many associations claim for more reduction of the noise emitted by vehicles. So can it be really a question that the main scope of engineering should be the development of cars as silent as possible? Noise or sound is something that is present even if it seems to be silent. Information are exchanged and emotions controlled. The answer to the above question is not only a technical one but also is touched by marketing and political issues. On the way through the global vehicle noise vibration and harshness (NVH) the following lecture shows that sound design and engineering, acoustic quality, customers expectations and noise legislation are the important areas to define the noise behavior of a car. |
Development of a Power Window Switch with Improved Ergonomics | This paper explains a methodology to develop a Power Window Switch (PWS) that is easy to operate. Many PWS knobs use a pivot movement. The most popular shapes are: 1.Pull-up/Push-down, 2.Rocker, and 3. Toggle. In the Pull-up/Push-down PWS, the knob motion matches the window motion. Since the design of the knob prevents an object or a part of clothing from catching, and pulling the knob up, potential injury from the window coming up is avoided. The knob top surface of the pull up PWS is pushed down to open the window, and the knob front surface is pulled up to close it. One weakness of this design is that the operating finger posture changes each time the window direction changes, the finger will often become tired with the repetitive posture changes. Another weakness of the Pull-up/Push-down PWS is the flush top surface of the knob to the bezel. The size of the knob and corresponding finger well limits the size of the finger and length of the fingernail. |
Design for Automotive Glass Removal Using Active Disassembly | Active Disassembly is a well researched technique for creating assemblies or casings that can break themselves apart for recycling using a heat trigger. ‘Chiodo’ has applied this principle to consumer electronic goods since the mid nineties. In response to pending EU legislation, the scope of active disassembly has broadened to include automotive disassembly. The first automotive demonstrators produced have been to make self-disassembling window glass retaining channels that enable easy glass removal for recycling. This waste glass can then be used in coastal defences as an alternative to landfill. Both shape memory alloy and shape memory polymer solutions have been examined. The shape memory alloy solution has been successful. Optimisation for the polymer solution is required. |
Glazing for Vehicle Interior Noise Reduction | As noise levels within vehicle cabins continue to be reduced, wind noise and traffic noise transmitted through the glazing increase in importance in the quest to achieve further reduction. With consumers ranking cabin noise as an important factor in vehicle purchase decisions, and with the projected increase in vehicle telematics, including speech recognition systems, the need for even quieter interiors will continue. NVH engineers have not recognized that vehicle glazing offers an effective option for noise reduction; often, only monolithic glass has been considered, where the only option for improvement has been to increase the mass (increasing the thickness and the vehicle weight). This paper presents sound pressure loss data for laminated glass compared to the tempered glass typically used for side, rear and roof glazing today. The sound pressure loss results show a significant opportunity for improvement in the 2000 to 6000 Hz region, a key range for human conversation and the key range for wind noise. Along with this acoustic improvement is a reduction in mass of the glazing. |
Increasing Performances by Using Multi-Thicknesses Blanks | Multi-thickness blanks (MTB) enable the dimensional optimization of steel parts by modulating thickness and mechanical properties. Traditionally, this is done by the addition of reinforcement to the basic part after the drawing of both. With MTBs, we first assemble the two flat blanks to obtain a single blank, which is then drawn without further assembly. MTBs comprise the Tailored Welded Blank (TWB), already widely used in automobiles, and a new category “Patchwork”. The TWB is a butt-welded assembly of two blanks with neither overlap nor superimposition. The patchwork blank is made by either the adhesive bonding or welding of a blank onto the surface of the base blank, at the point to be reinforced. These products enable the increase of performance objectives (impact, rigidity, vibration and fatigue resistance, etc.) whilst permitting weight reduction and thus adding to the potential of high resistance steels. They also enable, in numerous cases, the reduction of overall costs. Examples of applications are; side members, shock towers and pillar reinforcements. Illustration of design principles permitting the better understanding and exploitation of MTB potential are shown in this paper. |
3D Inside Vehicle Acoustical Holography | A continuously growing demand comes from the automotive industry in order to get an experimental tool allowing for the optimization of materials and sound insulating products implementation inside the car, so as to propose the best acoustic performance at reduced costs. The acoustical imaging system LORHA provides part of the solution and its demonstrated capability of measuring the acoustic field inside a vehicle makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings. This paper focuses on the methodology and recent operational results obtained within the tight collaboration established between METRAVIB RDS, its partner HUTCHINSON and well known car manufacturers. |
Trends and developments in Automotive Glass Encapsulation with PUR materials | The encapsulation of automotive glassparts started mid '80. It was a step forward in an attempt to supply ready-to-mount glass parts to the automotive production lines. These encapsulated glassparts have a moulded gasket all-around the periphery. Encapsulation can be done with different materials. In this lecture we will focus on the use of polyurethane (PUR) - more specific aliphatic polyurethane - and make a comparison with other materials such as PVC, TPE and EPDM. Since that time, encapsulation has really evolved from the original design function, towards a medium where more and more other elements can be integrated into the window. This can be combined with the fact that today large, complex and even laminated windows need to be encapsulated. Due to these functional integration opportunities the overall cost can be reduced combined with a much larger freedom of design and esthetics. |
Welding of Energy Management Systems and Air Duct Systems to Headliner | This paper reviews the use of vibration welding for joining crash impact pad's and air duct systems to headliner. Increasing government regulation and the evolution of automotive safety are demanding a new innovative welding technology for crash impact pad's as well air duct systems to the headliner. Vibration welding is an approved welding technology to join both similar and dissimilar materials and is used in many automotive applications is an innovative solution for such headliner applications. Driven by customer needs, energy management is an important consideration in protecting the occupants of a vehicle from injury in a crash situation. Air ducts are becoming more and more important to distribute air to the rear passenger. In this case both are placed between the headliner and the roof of the vehicle. Not only does vibration welding produce major cost savings, which is related to no consumables (no adhesive required), but also improves product quality, which means no smelling (no fogging through adhesive), and also provides higher pull off strength without variance with temperature is important in competition. |
“Active Mass Absorber” at a 4×4 Transmition System | The extensive use of rotative machines in the diverse branches of the modern world has made the rising undesirable mechanical and acoustic vibration levels to be a problem of special importance for the machines normal operation as for the communities that are each time more affected by the problem. It makes the study of vibration and acoustic phenomena also to be even more important and the applications of its concepts more sophisticated. Several are the concepts used for decreasing vibration levels, like common dampers, hydraulic dampers, active dampers, natural frequencies changes and others. The choice of use of one or another depends greatly on the engineering possibilities (weight, energy, physical space, other components functional interference, vibration levels, etc.) as well as the cost of implementation of each one. As a general rule, normal dumpers is usually the best method to decrease vibration levels, because of the smaller prices and not often collateral undesirable effects. In this work is presented a problem of vibration of the powertrain system of a 4×4 car that could not be easily solved by the use of normal dumpers and therefore another vibration-decreasing concept has been used: the “Active Mass Absorber”. “Dynamic Absorber” is a concept based on a phenomenon related to one specific vibration absorption by one auxiliary vibrating system attached to the main system, which the vibration level is wanted to be decreased. It works as it was draining the vibration movement of one specific frequency, so the main system vibration level decreases and the attached system (active mass damper) vibrates. In a normal car there are several exciting vibration and acoustic sources, such as the engine, tires, road roughness, air intake and exhaust system. The active mass absorber concept, which is designed for one only frequency absorption, is not an effective approach for the general vibration and acoustic problem solution. In the present study, however, the second order engine vibration was detected to be transmitted to the rear part of the car by the driveshaft and resonating in the back seats area. This resonation caused high sound pressure levels inside the vehicle and could not be decreased by normal dampers between the rear differential and the vehicle body. The solution proposed to this problem was attaching an active mass damper to the rear differential that absorbs part of the vibration energy before it flows to the car body. |
Application of LIN Network Interface for Ford South America Vehicles | Some communication buses are too powerful and expensive for simple digital on/off operations such as activating lights, wipers, windows, etc. For these applications the LIN bus is currently the most promising communication protocol across the world's automotive industry. This paper addresses a study using LIN (Local Interconnect Network) for Ford South America vehicles. This will propose a new electrical architecture designed with LIN network, which will be replacing the conventional rear and front lights cables in Trucks, where other higher protocols, such as CAN, are not cost effective. LIN is a new low cost serial communication system intended to be used for distributed electronic system that will allow gaining further quality enhancement and cost reduction on cables, connectors and switches. |
NVH Highlights and (Pot)Holes 1972-2001 | The NVH performance of motor vehicles has been improved dramatically during the 1972-2001 period. The paper identifies the main advances made, i.e. the development highlights and indicates a number of points where a lot of work still needs to be done (Holes or with and automotive flavor “Potholes”). The paper is structured as indicated below. 1 Introduction 2 Highlights 2.1 Vehicle 2.1.1 Body rigidity 2.1.2 Body leakage 2.1.3 Engine efficiency and vibration isolation 2.1.4 Suspension systems 2.2 Noise Control proper 2.2.1 Passby noise treatment and Aerodynamics 2.2.2 Interior treatment simulation and optimization 2.2.3 Noise Control material improvements 2.2.4 Multi-functional parts 2.2.5 Dissipative treatment packages 2.2.6 Noise Quality engineering 2.2.7 Development Methodology: Benchmarking 3 (Pot)Holes 3.1 Modeling car subsystems 3.2 Optimization; application to ever-larger subsystems 3.3 Simulation and Optimization of Passby Noise 3.4 Diagnostics 3.5 Materials and Shapes 3.6 Understanding the vehicle development process |
Improved Methodology for Dynamics of Orbiter Payload Bay Doors | The Payload Bay Door Dynamics Simulation (PBDS) computer program simulates the mechanical behavior of the space-shuttle payload bay doors and their latching and driving mechanisms during opening, closing, latching, and unlatching. PBDS was developed to replace an older program that was computationally inefficient and that simulated the door hinges incorrectly. In PBDS, the large system of dynamical equations of the payload-bay-door system is decomposed into smaller systems of dynamical equations at the mechanism level. This decomposition involves decoupling through neglect of the inertial parameters of the driving and latching mechanisms, which are small relative to those of the doors. The equations of motion of the doors, which are flexible, are derived by use of a Cartesian flexible-body formulation. The equations of motion of the mechanisms are derived by use of an efficient recursive formulation. Though decoupled dynamically, the door and the mechanisms are coupled kinematically. In solving the mechanism equations, the responses of the door at points where the door is attached to the mechanisms are fed as inputs to the mechanism equations. The outputs of the mechanism equations are forces and torques, which are fed back to the door equations to complete the computational cycle. |
Ford looks to spread Corning's new lightweight Gorilla Glass beyond the 2017 GT | While many supercar enthusiasts have “gone ape” over the Ford 2017 GT, the program development engineers have done the same for a new lightweight glazing solution. Called “Gorilla Glass,” the three-layer laminate is claimed by its supplier, Corning Inc., to deliver more than five times the strength, pound for pound, of conventional automotive glass while offering significant mass reduction. In the case of the GT, more than 12 lb (5.4 kg) was saved by using Gorilla Glass in three areas: the windshield (first use for a production vehicle), the rear window, and in an acoustic separator in the rear bulkhead. It also helped reduce the car's center of gravity by 3 mm (0.12 in). |
Opel designs a new Astra | Opel launched the fourth-generation Astra at the 2015 IAA (Frankfurt Motor Show). The car is more compact than the model it replaces and weighs up to 200 kg (440 lb) less. A five-door hatchback and five-door Sports Tourer estate were on display at the show. The Astra (a Vauxhall in the U.K.) will be the first vehicle to feature General Motors' OnStar Connectivity system in Europe and comes with the option of matrix LED headlights, which Opel claims is the first time this feature has been offered on a European C-segment car. |
Automotive Engineering International 2005-03-01 | Production preview from Detroit Attendees of the 2005 North American International Auto Show in the "Motor City" this January were treated to nearly 70 vehicle introductions, 24 of which were worldwide production cars and trucks. AEI editors present the technical highlights of some of the more significant 2005 and 2006 production vehicles. Significantly this year, the cars we've highlighted outnumber trucks by more than two to one. DSPs start progressing Math processors will help to provide more functionality in the cabin and improve motion contorl throughout the vehicle. Sliding doors the Toyota way Door openings are about more than hinges and pillars, according to the Japanese automaker. Accelerating technology Hybrid technology is gaining in popularity, broadening its scope to embrace performance, and driving industry collaborations. SAE 2005 World Congress preview General Motors is host company of the April 11-14 event, and has high expectations for its success in SAE's centennial year. Design "demarqueation" PSA's new design center will improve collaboration between teams while preserving individual brand identity, according to the company. Connected SAE 100 Future look: When an automotive designer is asked to envision a vehicle of the future, the response is likely to be, "Define the society of the future and I can create a vehicle responsive to that society." Tomorrow's smart car will make drivers better, smarter SAE 100 Future look: Driving on today's expressways is as dangerous as ever. Drivers face the daily challenges of extremely congested roads and distractions from cell phones, passengers, and even in-vehicle DVD systems. Powertrain electronics: a systems evolution SAE 100 Future look: Market forces, driven by consumer and regulatory demands, coupled with advances in technology, have created tremendous opportunities for engineering innovation. Telematics to focus on OEM ROI SAE 100 Future look: It is no secret that a couple yearas ago many in the automotive industry wrote off telematics as a dead issue. That chapter has long since passed, and what you will see emerge in the coming years is a reborn telematics industry that has little resemblance to what we have seen in the past. A gateway to the connected car SAE 100 Future look: Each generation of cars has not only brought drivers sleeker designs and more powerful engines, but also more advanced electronics in the form of features such as satellite radio and navigation. Testing resources This special edition of Product Briefs highlights some of the latest equipment used to develop cleaner, quieter, and safer vehicles. |
Improved Design for Manufacture in Minivan Body Systems | The design for manufacturability process has been recognized as a very effective method for improving the overall quality in mechanical product design. The first part of the paper deals with an extended DFM which encompasses all the various Quality issues in product development. The importance of the three major elements quality, cost and timing are highlighted in the mathematical model for Design for Quality (DFQ). The second part of the paper describes the application of DFQ in the design and development of minivan body and interior systems. The best value of the DFQ is recognized when the process is used proactively during the early stages of the development cycle. Such is the case of the applications discussed in this paper which covers the following systems: hood assembly, seamless door system, sliding door system, instrument panel and message center installation, and fuel filler door-and-housing system. |
Comparison of Airbag-Aggressivity Predictors in Relation to Forearm Fractures | Four unembalmed human cadavers were used in eight direct-forearm-airbag-interaction static deployments to assess the relative aggressivity of two different airbag modules. Instrumentation of the forearm bones included triaxial accelerometry, crack detection gages, and film targets. The forearm-fracture predictors, peak and average distal forearm speed (PDFS and ADFS), were evaluated and compared to the incidence of transverse, oblique, and wedge fractures of the radius and ulna. Internal-airbag pressure and axial column loads were also measured. The results of this study support the use of PDFS or ADFS for the prediction of airbag-induced upper-extremity fractures. The results also suggest that there is no direct relationship between internal-airbag pressure and forearm fracture. The less-aggressive system (LAS) examined in this study produced half the number of forearm fracture as the more-aggressive system (MAS), yet exhibited a more aggressive internal-pressure performance. Both the peak-internal pressure and the initial-inflation rate of the LAS were higher than for the MAS, but the PDFS, ADFS, and axial column loads of the LAS were lower. This inverse relationship between internal-airbag pressure and airbag aggressivity prompted an investigation of the LAS and MAS design characteristics. The closed-module design of the LAS, coupled with longer, thicker tear seams, results in higher peak-internal pressures and greater rates of pressure increase when compared to the MAS. Therefore, more inflator energy must be used to achieve bag egress from the LAS module, making less energy available to be imparted to a forearm. The reduced and more distributed mass and size of the LAS doors may assist in the reduction of focused energy transfer to a forearm and the less-aggressive-tank-test characteristics compared to the MAS inflator. A combination of these factors causes a reduction in the level of fracture predictors, such as PDFS and ADFS, when using the LAS, and a reduction in the incidence and severity of forearm fractures. |
Preliminary Studies on the Effects of Injection Rate Modulation on the Combustion Noise of a Common Rail Diesel Engine | The present work deals with tests on a DI Diesel engine equipped with two different types of Common Rail injectors, the second one allowing a “smoother” fuel rate in the first stage of injection. The work aims at understanding how injection parameters and different injection rates may affect the combustion process in terms of in-cylinder pressure, noise and vibrations of the engine block. The tests performed for the same engine torque generally showed that engine speed, injection pressure and pilot injection duration are the most significant parameters that affect engine noise emissions. As regards the injection rate modulation, experiments showed that it is possible to reduce combustion noise at low engine speeds if the initial rate of injection is lower during the first stage of injection. |
Friction-Induced Vibrations of Window Sealing Systems | The problem of squealing from vehicle windows opened or closed in partly wet conditions has been investigated. Experiments were conducted using a glass-run seal sample and a tangentially moving glass piece installed on a test bench. The instantaneous velocity of the glass was measured along with the total dynamic frictional force for varying normal static loads and sprayed-water distributions. The characteristics of squeal vibrations and the influence of normal load and water distribution are discussed. The relation between friction force and speed was also investigated. An idealized model consisting of a one-dimensional continuous rod excited by a moving frictional point force was then investigated. The method of averaging was applied to solve the nonlinear equations of motion. The response became unstable when the magnitude of the negative slope and the normal force were large regardless of boundary conditions. Frequency jumps appeared in the numerical simulations due to the variation of the modal amplitudes according to the position of the contact force on the rod. The model provided an adequate qualitative description of many of the trends observed in the experiments. |