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Technical Paper

Validation of Wireless Power Transfer up to 11kW Based on SAE J2954 with Bench and Vehicle Testing

Wireless Power Transfer (WPT) promises automated and highly efficient charging of electric and plug-in-hybrid vehicles. As commercial development proceeds forward, the technical challenges of efficiency, interoperability, interference and safety are a primary focus for this industry. The SAE Vehicle Wireless Power and Alignment Taskforce published the Recommended Practice J2954 to help harmonize the first phase of high-power WPT technology development. SAE J2954 uses a performance-based approach to standardizing WPT by specifying ground and vehicle assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies. This type of testing had not been done before on such a scale with real automaker and supplier systems.
Technical Paper

User Friendly Trucks

Today trucks account for close to half of the US passenger vehicle market. And customers expect more and more from their trucks in terms of comfort and convenience features. The key to developing Best-in-Class comfort and convenience attributes lies in applying Ergonomic principles to the vehicle interior design. Lear Corporation has recently studied 4 truck interiors in the Sport Utility Market Segment focusing on Ergonomic design issues. This paper will review the Sport Utility study results and make interior design recommendations. In this market, functionality is of primary importance to customers. Using random samples of truck owners, we have examined the functionality of door panels, consoles, controls, cupholders, cargo covers and the rear cargo area. Several factors ranging from reach criteria, tactile feel and usability through operating efforts and the motion required to operate the various features were examined.
Technical Paper

Use of Layered Media for Noise Abatement in Automotive Interiors: A Balanced Approach

Concepts for dual density materials for usage as absorbers and decouplers are based on well-established layered media principles and have been applied for many years in non-automotive applications. Balancing the mass, air flow resistance, and thickness allows for improved noise attenuation in the low to mid frequency range which is of particular interest for automotive NVH management. Using these principles, products were tuned via mass and airflow resistance to reduce noise levels while also significantly reducing mass. Validation in various vehicles confirmed that up to a 55% reduction of a sound package's mass is possible. The considerable weight reductions of dash insulators and carpet systems are possible at the same times as the sound level in the vehicle interior is at least maintained and frequently improved.
Technical Paper

The Use of in Vehicle STL Testing to Correlate Subsystem Level SEA Models

For the assessment of vehicle acoustics in the early design stages of a vehicle program, the use of full vehicle SEA models is becoming the standard analysis method in the US automotive industry. One benefit is that OEM's and Tier 1 suppliers are able to cascade lower level acoustic performance targets for NVH systems and components. Detailed SEA system level models can be used to assess the performance of systems such as dash panels, floors and doors, however, the results will be questionable until test data Is available. Correlation can be accomplished with buck testing, which is a common practice in the automotive industry for assessing the STL (sound transmission loss) of vehicle level components. The opportunity to conduct buck testing can be limited by the availability of representative bodies to be cut into bucks and the availability of a transmission loss suite with a suitably large opening.
Technical Paper

The Use of Subjective Jury Evaluations for Interior Acoustic Packaging

Unweighted dB, dB(A), and Articulation Index do not always accurately identify the sound quality of vehicle interior noise. This paper attempts to determine the relevance of sound quality in interior automotive acoustics. Traditionally, overall dB(A) levels have been the driving factor, along with cost, in selecting an interior automotive acoustic package. In this paper, we make use of subjective jury evaluations to compare perceptions of various interior acoustic packages and compare these results to objective values. These values include, but are not restricted to, dB, dB(A), and Articulation Index. Considerations are made as to whether differences between packages can be perceived by customers. This paper also attempts to show that subjective evaluations can differ with the standard metrics used to select acoustic packages and describe why such evaluations might be important in acoustic package selection.
Technical Paper

The Development of a Sound Quality-Based End-of-Line Inspection System for Powered Seat Adjusters

In recent years, the perceived quality of powered seat adjusters based on their sound during operation has become a primary concern for vehicle and seat manufacturers. Historical noise targets based on overall dB(A) at the occupant's ear have consistently proved inadequate as a measure of the sound quality of a seat adjuster. Significant effort has been devoted to develop alternative sound quality metrics that can truly discriminate between “good” and “bad” seat adjusters. These new metrics have been successfully applied for some years by product development engineers in test labs. However, in the assembly plant the sound quality of the seat adjuster is still assessed subjectively by an operator at the end of the assembly line. The main problem with this approach is not only the lack of consistency and repeatability across large samples of seat tracks, but also the fact that the only feedback provided from the end-of-line to the product development team is of subjective nature.
Technical Paper

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.
Technical Paper

Static Electricity in Automotive Interiors

Seats and carpets were evaluated for generating static charges on vehicle occupants. Active measures that eliminate or reduce static accumulation, and passive measures that dissipate static charge in a controlled manner were investigated. The active measures include using durable anti-static finishes or conductive filaments in seating fabrics. The passive measures include adopting conductive plastics in a steering wheel, seat belt buckle release button, or door opening handle. The effectiveness of these measures was tested in a low humidity environment.
Technical Paper

SAE Recommended Formats for Presenting Acoustical Data

Automobile manufacturers recently requested the help of the SAE Acoustical Materials Committee to develop standard data formats that could be used by suppliers to present data on NVH products. An SAE task force with representatives from material suppliers and from OEMs chose formats covering a broad range of acoustical tests commonly conducted in the automotive industry. These formats cover both material and vehicle tests. They include details on samples and test conditions and graphs with preferred axes and data ranges. SAE recommended practice J2629 will be issued that describes the use of these preferred formats for acoustical data. The automobile manufacturers have requested that all suppliers of NVH products use these formats to present results from this point onward.
Technical Paper

Reducing Background Noise Levels in Plant SQ Test Booths

As customer awareness of product sound grows, the need exists to ensure that product sound quality is maintained in the manufacturing process. To this end in-process controls that employ a variety of traditional acoustical and alternate sound quality metrics are utilized, usually partly or wholly housed in a test enclosure. Often times these test cells are required to attenuate the background noise in the manufacturing facility so that the device under test can be accurately assessed. While design guidelines exist the mere size and cost of such booths make an iterative build and test approach costly in terms of materials as well as engineering and testing time. In order to expedite the design process and minimize the number of confirmation prototypes, SEA can be utilized to predict the transmission loss based upon material selection and booth construction techniques.
Technical Paper

Recovery of Selected Engineering Plastics from Automotive Shredder Residue Using Skin Flotation Technology

Recovery of metals from automobile shredder residue (ASR) is currently being applied to over 11 million end of life vehicles (ELV) in North America. However, most plastics from these vehicles become landfill. The Vehicle Recycling Partnership (VRP), an effort of Chrysler, Ford, and General Motors, as part of the USCAR initiative, has been conducting research to recover plastics from this ASR feed stream. The VRP has been working with Recovery Plastics International (RPI), to investigate automated plastic separations. RPI has been developing processes that would allow for fully automated recovery of target engineering plastics. The portion of the process developed for separating the engineering plastics is called skin flotation. This technology can separate engineering plastics even if the materials have the exact same density. A pilot production line has been set up for processing a variety of commercial ASR materials at RPI in Salt Lake City, Utah (USA).
Technical Paper

Package Tray Optimization Using Experimental and Analytical Techniques

The area in the neighborhood of the package tray can be a significant path for road noise and exhaust noise. Air extraction routes and loudspeakers add to the difficulty of effective system design. A variety of designs were prototyped and their transmission loss measured in a standard SAE J1400 sound transmission loss suite. The performance of the various designs was compared to an untrimmed piece of sheet metal with embedded air extraction holes. The addition of trim added from 1 dB to 14 dB to the transmission loss. Statistical energy analysis (SEA) models of a variety of package tray systems will also be shown. Both of these techniques can provide design guidance at an early stage of vehicle program development.
Technical Paper

OneStep™ Liftgate

Lear Corporation has developed a new OneStep™ Liftgate trim module. The panel consists of all mechanical components and a trim cover assembled into one module. This structural liftgate uses the trim substrate and a “beam” as the common attachment point for all liftgate hardware. The assembly includes all of the liftgate components mounted to the back of the interior trim panel.
Technical Paper

Noise Absorption of Automotive Seats

Seat covers made from textiles, leather and vinyl were evaluated for noise absorption. The textiles included woven velours, pile knits and flat wovens. The noise absorption of the covers and the corresponding seat assemblies was tested by the reverberation room method per ASTM C423. The effect of different foams was also tested. For the leather and vinyl covers, the effect of perforation was evaluated. Test results showed distinctive differences between textiles and leather/vinyl with cloth seats having superior noise absorption. Even among the textiles, there are significant differences. Core foam densities affect the characteristics as well. For pile fabrics (woven velours and pile knits), the size of the pile fiber does not affect the acoustic characteristics of the seat. Also, no significant difference was observed between a bonded seat and a conventional (cut and sew) seat.
Technical Paper

Monotonic and Fatigue Behavior of Magnesium Extrusion Alloy AM30: An International Benchmark Test in the “Magnesium Front End Research and Development Project”

Magnesium alloys are the lightest structural metal and recently attention has been focused on using them for structural automotive components. Fatigue and durability studies are essential in the design of these load-bearing components. In 2006, a large multinational research effort, Magnesium Front End Research & Development (MFERD), was launched involving researchers from Canada, China and the US. The MFERD project is intended to investigate the applicability of Mg alloys as lightweight materials for automotive body structures. The participating institutions in fatigue and durability studies were the University of Waterloo and Ryerson University from Canada, Institute of Metal Research (IMR) from China, and Mississippi State University, Westmorland, General Motors Corporation, Ford Motor Company and Chrysler Group LLC from the United States.
Technical Paper

Modeling the Vibro-Acoustical Behavior of Composite Multi-layered Systems

Composite multi-layered systems are of particular interest in the automotive industry since the design of the various components in an efficient sound package requires a good predictive model. The state of the art in this matter shows that the medium and high frequency ranges are well mastered in terms of predictive tools based on infinite models. But this is not the case for the lower frequency range. The paper will start with a discussion of the medium and high frequency range where, for example, the Transfer Matrix Method (TMM) is an efficient framework to predict the acoustical properties of multi-layer materials. Emphasis will be put on correlation data obtained with a variety of multi-layer systems. In the low frequency range the use of infinite models leads to significant discrepancies. In the present paper the authors propose a finite “hybrid type” formulation which combines the advantages of both single layer and multi-layer approaches of stratified composite structures.
Technical Paper

Human Modeling: Controlling Misuse and Misinterpretation

Human models are viable methods of introducing human factors and ergonomic objectives into the design process at an early stage. Used correctly, they allow users to simulate and analyze potential human-machine interactions saving time and money. As with any model, mistakes can be made. The primary sources of error stem from incorrect use and misinterpretation of the results by the analyst. The development of three-dimensional human modeling software has only compounded these issues by adding a digital subject, itself a human model. This complicates the interpretation and use of these tools by layering one human model on top of another. The purpose of this paper is to highlight common categories of misuse and misinterpretation of digital human models as well as to propose a method for improving user understanding of human models through formal documentation of critical components.
Technical Paper

Empirical Study on the Correlation of Random Incidence Sound Absorption Results from Varying Reverberation Room Sizes

Recent effort has focused on correlating random incidence absorption coefficients obtained in different sizes of reverberation rooms based on round robin testing of identical samples in a database driven approach. An alternate approach presented here is to correlate random incidence sound absorption coefficients among different reverberation rooms using an apparent linear relationship between sound absorption coefficients and a geometric property of the test samples. Linearity can be judged in relation to the uncertainty of each individual measurement. The study will encompass experimental work on three different sizes of reverberation rooms for both a single layer material and a multi-layered material. By examining the different sound absorption coefficient values from each size of room, as a function of geometric parameters, we illustrate the quantitative correlation that might be established between the different sizes reverberation rooms.
Technical Paper

Elastomeric Seats-Automotive Seats with Multifunction Fabric

New fabrics which function as covering material as well as suspension have been developed. These fabrics eliminate the need of underlying foam and suspension springs. They can look like mesh, flat or pile fabrics. The moduli of the fabric have to be controlled to yield the proper suspending and damping characteristics. Effects of environments including UV, ozone and heat exposures were evaluated. Different versions of seats have been built to demonstrate the applications of the new fabric. Advantages of using the fabric are outlined.