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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.

The optimization of acoustical properties of multi-layered materials used in the automotive industry requires a good understanding and characterization of the various component layers. This is a particular concern in the case of headliners where performance must be balanced with packing space demands. These composite structures when used with flexible urethane foams provide good stiffness and light weight, but their acoustic performance can be sub-optimal. Measurements undertaken with poro-elastic high airflow resistivity foams highlighted frame resonances which, if exploited, might significantly improve the acoustical performance of this system. A new modeling technique based on a pseudo-macroscopic description of the poro-elastic material in the framework of a four-pole network will be used to explain these frame resonances. This formulation exploits the electro-acoustical analogy in transmission line theory.

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.

This paper discusses an analytical tool that has been developed to predict what types of interior sound package treatments may be necessary in a truck cab to meet a predetermined target sound level at the driver location. The steps that were taken to develop this tool involved a combination of experimental measurement and analytical based studies. Measurements were conducted to identify the acoustic strengths of the major noise paths through which sound travels from outside to inside the truck. These findings were then used to develop a sound package that reduced the vehicle interior noise to meet the target. Measurements were primarily made on a chassis roll dynamometer with final road verification to substantiate the dynamometer data. Data obtained from these measurements were also used in the analytical model that predicts the impact of various acoustics parts in the vehicle, and has the capability to optimize the sound package treatment in the vehicle.

Many automotive ECU system issues do not manifest themselves until later in the vehicle product development cycle, despite the extensive testing and stringent validations that the ECU may have gone through. When such a system-level issue is identified, engineers will traditionally rely on the available information collected from logged DTCs and memory dumps to root-cause the issue. They will then develop a solution that will either eliminate the defects in ECU or develop a robust design to mitigate the impact. However, engineers are faced with technical difficulties which include: (a) physical addresses for many RAM variables critical to find the root-cause are subject to change with various releases of software, (b) some variables “come and go” so it is challenging to find out how and when the undesired events happen, and (c) many variables that are needed to identify the root-cause are missing.

When characterizing absorption in vehicles, a knowledge of the in situ performance of the acoustical absorbers is often desired. To measure this is a relatively easy task in a large diffuse sound field. However, inside a vehicle where the sound field is not diffuse, the measurement is more difficult. Impulse and interrupted noise techniques have been used to measure absorption inside cavities with extremely short reverberation times. Among several difficulties associated with these techniques are the response time of the filters and the influence of the averager in the instrumentation. In many cases, these limitations make these traditional techniques impractical for use in a vehicle. With the advent of modern digital signal processing, however, there are a number of other readily accessible techniques that are more useful.

Recent changes to the FMVSS 201 require the use of a Free Motion Headform (FMH) to meet a HIC(d) value of 1000. As the FMH impacter test involves the use of a featureless Hybrid III headform, this head must relax for three hours after each impact to allow the skin to normalize. This severely limits the amount of tests that one can perform in a given period of time. This paper will discuss various test methods that do not require a relaxation period between impacts that correlate to the FMH impacter test.

The purpose of this study was to determine the optimal location of the shoulder belts for a suspender style four-point safety belt system. This optimal location must satisfy two conditions. First, the shoulder belts must properly fit over the occupant’s shoulders for safety performance. Second, the shoulder belts location on the occupant’s body must be acceptable to the occupant. To determine the optimal acceptable location of the shoulder belts, forty-four subjects were recruited by height and tested in a reconfigurable test seat. The results showed that avoiding an interaction between the shoulder belts and the occupant’s neck improved the acceptability of the system. Variables that affected this interaction included the horizontal and vertical position of the shoulder belts and the occupant’s weight, clothing, and gender.

The increasing complexity and competition in the car market pushes OEMs to simultaneously achieve both a lead-time reduction and a higher development process productivity. Therefore, car manufacturers are asked to significantly revise their development and production procedures, together with their suppliers who are co-designers vehicle-systems (seating, dashboard, lighting, etc.). Innovative CAD tools, such as parametric and associative (p/a), may significantly increase efficiency and effectiveness of design activities, through assisted procedures, automatic checking of constraints, avoidance of repetitive handle operations. By this way, p/a CAD tools may reduce the time requested for geometry description and modification, leaving the designer more opportunities for studying the design solution.

Published in 1996, as the 100th Anniversary of the automobile industry was celebrated in the United States, this book details the amazing story of how Detroit become the automobile capital of the U.S. All the of the automobile manufacturers in Detroit and surrounding areas are covered along with 49 additional topics that are woven in-between and presented in chronological order. This book includes over 500 time period photographs of factories, both inside and outside, personnel, cars, and logos. Readers will gain an appreciation for the talented people that created Detroit's automobile industry.