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The Ford GT Program Team was allocated just 22 months from concept to production to complete the Electrical and Electronics systems of the Ford GT. This reduced vehicle program timing - unlike any other in Ford's history -- demanded that the team streamline the standard development process, which is typically 54 months. This aggressive schedule allowed only 12 weeks to design the entire electrical and electronic system architecture, route the wire harnesses, package the components, and manufacture and/or procure all components necessary for the first three-vehicle prototype build.

Ford GT 2005 vehicle was designed for performance, timing, cost, and styling to preserve Ford GT40 vintage look. In this vehicle program, many advanced manufacturing processes and light materials were deployed including aluminum and magnesium. This paper briefly explains one unique design concept for a Ford GT instrument panel comprised of a structural magnesium cross-car beam and other components, i.e. radio box and console top, which is believed to be the industry's first structural I/P from vehicle crash load and path perspectives. The magnesium I/P design criteria include magnesium casting properties, cost, corrosion protection, crashworthiness assessments, noise vibration harshness performance, and durability. Magnesium die casting requirements include high pressure die cast process with low casting porosity and sound quality, casting dimensional stability, corrosion protection and coating strategy, joining and assembly constraints.

Continuing effort in measuring human vibration response results in a new design of vibration comfort dummy. The difference between this new dummy and other mechanical dummies is that (1) it uses a soft human-tissue like lower torso so it matches compliance better than the previous ones, and (2) it utilizes the spring and damping characteristics of the compliant lower torso. The lower torso is integrated with a spring-mass load simulating the top body of human so that the integrated dummy consists of two parts. This unique design greatly improves the accuracy and stability of transmissibility measurement and provides a direct application tool in seat prototype development. The results measured with dummy are compared with that measured with 3 human subjects in different percentiles and good match is found in the first transmissibility resonance and overall vibration response.

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.

Perforating certain layers of laminated material can improve the sound absorption performance of the material. The hole size, shape, angle, spacing and pattern can be tuned to improve sound absorption in a certain frequency range using a validated acoustical model. The model is based on a numerical calculation of acoustical properties of porous multi-layers using a transfer matrix method in the context of the Biot theory in NOVA software. An additional calculation of airflow resistivity and porosity from the hole size and hole spacing is also conducted. The model predictions agree with the testing data. Based on this model, the acoustical performance of the material can be optimized to meet vehicle acoustical requirements. The vehicle level SEA models are used to examine the effects of the perforation on the vehicle interior acoustics.

The approaches used to develop an NVH package for a vehicle have changed dramatically over the last several years. New noise and vibration control strategies have been introduced, new materials have been developed, advanced testing techniques have been implemented, and sophisticated computer modeling has been applied. These approaches help design NVH solutions that are optimized for cost, performance, and weight. This paper explains the NVH practices available for use in designing vehicles for the new millennium.

Many studies have been done to objectively measure car seat foam properties and correlate them to comfort performance. Typically, the vibration characteristics (namely transmissibility) of the foam cushion are measured. It has been generally accepted that low natural frequency equates to better comfort. However, no subjective studies have been done to verify that humans can feel the vibration differences that are measured. Also, the measured differences of the foam may not be detectable once the foam is built into a complete seat. Three different foam formulations utilizing MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate) technology were evaluated for vibration characteristics. The foams were then submitted to subjective human testing and objective lab testing after being built into seats. The subjective testing was done using a typical ride and drive evaluation where people were interviewed about the comfort of the seat while driving over various road conditions.

Size is one of the most basic and important factors when determining fit for people. Many methods used to test occupant fit and accommodation rely on a traditional set of three different sized manikins - 5th, 50th and 95th percentiles. Anthropometry, the study of human size dimensions, however, is a complex multivariate problem. Real people, real drivers are a mixture of dimensions tall thin, short, stout, etc. This paper examines population anthropometry and these traditional percentiles specific to vehicular seat design.

In order to more accurately simulate the load distributions and histories experienced by automotive seats in field use, more biofidelic motion and loading devices are needed. A new test dummy was developed by Lear Corporation and First Technology Safety Systems. This dummy uses exact skeletal geometry encased in a one-piece seamless mold with contours based on ASPECT data. A prototype was constructed and tested to demonstrate the efficacy of the concept. The skeleton and contour molds were created from CAD-generated rapid prototypes. The flesh was carefully formulated to have the mechanical properties of bulk muscular tissue in a state of moderate contraction, using data from the literature. This design allows much greater accuracy in reproducing human loads than was ever possible previously. The design has applications in durability, vibration and comfort testing.

In order to more accurately simulate the load distributions and histories experienced by automotive seats in field use, more biofidelic motion and loading devices are needed. Lear and KUKA have developed a system capable of controlling the coordinated motions of a pelvis, thighs and torso dummy in order to mimic human motions. The system takes kinematic data collected from human trials and converts them directly to a robot program. Additionally, simultaneous measures of human loading using pressure distribution mats can be obtained, and these measures are used as the basis for teaching the robot to correct the kinematic data using a neural net learning algorithm. The robot has direct and indirect load feedback integration that allows the load to be precisely maintained throughout the duration of a cycle test.

Interior noise has become a significant performance attribute in modern passenger vehicles and this is extremely important in the luxury market segment where a quiet interior is the price of entry. With the elimination of early prototype vehicles to reduce development costs, high frequency analytical SEA models are used to design the vehicle sound package to meet targets for interior noise quality. This function is important before representative NVH prototypes are available, and later to support parameter variation investigations that would be cost prohibitive in a hardware test. This paper presents the application of an analytical full vehicle SEA model for the development of the acoustic package of a cross over luxury utility vehicle. The development concerns addressed were airborne powertrain noise and road noise. Power flow analysis was used to identify the major noise paths to the interior of the vehicle.

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.

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.

The Ford GT is a niche vehicle with a very limited production volume. A solution was needed that would minimize cost, particularly up-front investment, and produce a lightweight, high-class vehicle interior, while maintaining the standard quality, material and design requirements.

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.

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.

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.

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.

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).

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.