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Brake torque variation is a source of objectionable NVH body/chassis response. Such input commonly results from brake disk thickness variation. The NVH dynamic characteristics of a vehicle can be assessed and quantified through experimental modal testing for determination of mode resonance frequency, damping property, and shape. Standard full vehicle modal testing typically utilizes a random input excitation into the vehicle frame or underbody structure. An alternative methodology was sought to quantify and predict body/chassis sensitivity to brake torque variation. This paper presents a review of experimental modal test methodologies investigated for the reproduction of vehicle response to brake torque variation in a static laboratory environment. Brake caliper adapter random and sine sweep excitation input as well as body sine sweep excitation in tandem with an intentionally locked brake will be detailed.

Brake judder, which is a low frequency excitation of the suspension and thus, the body structure during low-G braking, is mainly felt at the steering wheel and throughout the vehicle structure. Brake judder is a problem that costs manufacturers millions of dollars in warranty cost and undesirable trade offs. The magnitude of judder response depends not only on the brake torque variation, but also on the suspension design character-istics. This paper discusses the judder simulation process using ADAMS software to investigate the suspension design sensitivity to the first order brake judder performance. The paper recommends “tuning knobs” to suspension designers and vehicle development engineers to resolve issues in the design and development stages. Various suspension design varia-bles including geometry and compliances as well as brake related characteristics were investigated.

To mitigate head impact injuries of vehicle occupants in impact accidents, the FMVSS 201 requires padding of vehicle interior so that under the free-moving-head-form impact, the head injury criterion (HIC) is below the limit. More recently, pedestrian head impact on the vehicle bonnet has been a subject being studied and regulated as requirements to the automobile manufacturers. Over the years, the square wave has been considered as the best waveform for head impacts, although it is impractical to achieve. This paper revisits the head impact topic and challenges the optimality of aiming at the square waveform. It studies several different simple waveforms, with the objective to achieve minimal HIC or minimal crush space required in head-form impacts. With that it is found that many other waveforms can be more efficient and more practical than the square wave, especially for the pedestrian impact.

The problem of predicting the quality of weld is critical to manufacturing. A great deal of data is collected under multiple conditions to predict the quality. The data generated at Daimler Chrysler has been used to develop a model based on grammatical evolution. Grammatical Evolution Technique is based on Genetic Algorithms and generates rules from the data which fit the data. This paper describes the development of a software tool that enables the user to choose input variables such as the metal types of top and bottom layers and their thickness, intensity and speed of laser beam, to generate a three dimensional map showing weld quality. A 3D weld quality surface can be generated in response to any of the two input variables picked from the set of defining input parameters. This tool will enable the user to pick the right set of input conditions to get an optimal weld quality. The tool is developed in Matlab with Graphical User Interface for the ease of operation.

A new realistic motion control algorithm for digital human models is presented in this paper based on the principle of effort minimization. The proposed algorithm is developed through an innovative mathematical model to make the applications more flexible and more global, especially for the visualization of human motions in automotive assembly operations. The central idea of this unique model is to interpret the solution of the homogeneous Lagrange equation for a mannequin as the origin of dynamic motion. Furthermore, a digital human possesses about 42 joints over the main body except the head, fingers and toes, and offers a large room of kinematic redundancy. We have found 14 new 3-D independent motion markers assigned over the human body to constitute a Cartesian coordinate system, under which a minimum-effort based dynamic control scheme is developed using a state-feedback linearization procedure.

The effects of vehicle “stiffness” and mass on the occupant response during a crash may be determined by evaluation of accident data. However, “stiffness” and mass may be correlated, making it difficult to separate their effects. In addition, a single-valued “stiffness”, although well defined for linear case, is not well defined for non-linear systems, such as in vehicle crash, making the separation task even more difficult. One approach to addressing the lack of a clear definition of stiffness is to use multiple definitions. Each stiffness definition can then be correlated with mass to look for trends. In this study, such an approach was taken, and the different stiffness definitions were given and their values were obtained from rigid barrier crash test data. No clear relationship between mass and stiffness appears to exist. All the stiffness measures reviewed show, at best, only a weak correlation with mass. A stiffness analysis among different vehicle types was also carried out.

The Hybrid III family of dummies is used to estimate the response of an occupant during a crash. One recent area of interest is the response of the neck during air bag loading. The biomechanical response of the Hybrid III dummy's neck was based on inertial loading during crash events, when the dummy is restrained by a seat belt and/or seat back. Contact loading resulting from an air bag was not considered when the Hybrid III dummy was designed. This paper considers the effect of air bag loading on the 5th percentile female Hybrid III dummies. The response of the neck is presented in comparison to currently accepted biomechanical corridors. The Hybrid III dummy neck was designed with primary emphasis on appropriate flexion and extension responses using the corridors proposed by Mertz and Patrick. They formulated the mechanical performance requirements of the neck as the relationship between the moment at the occipital condyles and the rotation of the head relative to the torso.

One of the major NVH concerns for automobile manufacturers is the response of a vehicle to the impact of the tire as it encounters a road discontinuity or bump. This paper describes methods for analyzing the impact response of a vehicle to such events. The test vehicle is driven on a dynamometer, on which a bump simulating cleat is mounted. The time histories of the cleat impact response of the vehicle can be classified as a transient and a repeated signal, which should be processed in a special way. This paper describes the related signal processing issues, which include converting the time data into a continous spectrum, determination of the correct scaling factor for the analyzed spectrum, and smoothing out harmonics and fluctuations in the signal. This procedure yields a smooth frequency spectrum with a correctly scaled amplitude, in which the frequency contents can be easily identified.

The goal of an OEM electrical/electronics (E/E) platform organization is to release reliable E/E systems that achieve high levels of customer satisfaction with minimum investment and system cost. Achieving this goal is made more challenging by rapid advances in E/E technology and features which impact the vehicle development business environment. This paper discusses the evolution of an OEM platform organization striving to achieve E/E system integrity in an ever-changing world and eventually achieved the world class electrical quality as measured by J. D. Power. The organizational evolution progresses through a series of philosophies and methodologies, adapting new initiatives and enablers seeking continuous improvement. The result is an OEM organization with: knowledge based on lessons learned, an understanding of E/E system architecture, and enabled by models and tools to provide high levels of customer satisfaction.

Mechanical properties of as-rolled steels used in a vehicle vary with many parameters including gages, steel suppliers and manufacturing processes. The residual forming and strain rate effects of automotive components have been generally neglected in full vehicle crashworthiness analyses. Not having the above information has been considered as one of the reasons for the discrepancy between the results from computer simulation models and actual vehicle tests. The objective of this study is to choose the right material property for as-rolled steels for stamping and crash computer simulation, and investigate the effect of forming and strain rate on the results of full vehicle impact analyses. Major Body-in-White components which were in the crash load paths and whose material property would change in the forming process were selected in this study. The post-formed thickness and yield stress distributions on the components were estimated using One Step forming analyses.

This paper contains a review of methods for deriving risk curves from biomechanical data obtained from impact experiments on human surrogates. It covers many of the problems and pitfalls of obtaining realistic human risk curves from impact experiments. The strength and weakness of both parametric and non-parametric methods are evaluated. The limitations of standard analysis of censored impact test data are presented. Methods are given for determining risk curves from both doubly censored data and data obtained from impacts to body regions in which there are more than one mechanism of injury. A detailed set of examples is presented in which different experimental data are analyzed using the Consistent Threshold method and the logistic approach. Finally risk curves for published data are presented for the femur, head, thorax, and neck.

As the standards for exhaust emissions have become more stringent, the quality control tools used to evaluate the performance of low level samplers and analyzers has become more important. The Vehicle Exhaust Emissions Simulator (VEES) was developed to evaluate the performance of vehicle or engine exhaust emissions sampling and analytical systems. The simulator emulates emissions from low-emitting gasoline vehicles by producing a simulated exhaust stream containing emission constituents (HC, CO, CO2, and NOx) injected via Mass Flow Controllers (MFCs). This paper discusses various applications of the VEES as a quality control tool for ULEV and SULEV testing. A comparison is made between the injected amount of exhaust species by the VEES and the amounts recovered by the different sampling systems. Different root cause scenarios are discussed as to the source of discrepancies between the results on the CVS and BMD for different driving cycles.

It is becoming increasingly difficult to obtain good repeatability from running lab vehicle correlation testing, since vehicle variability is so significant at the Low ULEV and SULEV emissions levels. These new emission standards are becoming so stringent that it makes it very difficult to distinguish whether a problem is a result of vehicle variability, test cell sampling or the analytical system. A vehicle exhaust emission simulator (VEES) developed by Horiba, can simulate emissions from low emitting gasoline vehicles by producing tailpipe flow rates containing emissions constituents ( HC, CH4, CO, NOx, CO2 ) injected at the tailpipe flow stream via mass flow controllers.

Laser lap welding quality is a non-linear response based on a host of categorical and numeric material and process variables. This paper describes a Grammatical Evolution approach to the structure identification of the laser lap welding process and compares its performance with linear regression and a neuro-fuzzy inference system.

Today automotive thermal systems development is a joint effort between an OEM and its suppliers. This paper presents a pilot program showing how OEMs and suppliers can jointly develop a reliable and robust thermal system using CAE tools over the internet. Federated Intelligent Product Environment (FIPER) has been used to establish B2B communication between OEMs and suppliers. Suppliers remotely run thermal systems computer models at the OEM site using the FIPER B2B feature.

Over the past five years, the US Automotive Materials Partnership (USAMP) has brought together representatives from DaimlerChrysler, General Motors, Ford Motor Company and over 40 other participant companies from the Mg casting industry to create and test a low-cost, Mg-alloy engine that would achieve a 15 - 20 % Mg component weight savings with no compromise in performance or durability. The block, oil pan, and front cover were redesigned to take advantage of the properties of both high-pressure die cast (HPDC) and sand cast Mg creep- resistant alloys. This paper describes the alloy selection process and the casting and testing of these new Mg-variant components. This paper will also examine the lessons learned and implications of this pre-competitive technology for future applications.

Faced with an ever increasing supply of road load data and no reasonable means to keep track of it, Managing Road Load Data and The Process is about one engineer's charge to deliver a solution. This paper summarizes the approach taken by this engineer and his team to produce a system that not only provides a place to store their data, but facilitates the entire data collection, validation and dissemination process. By following the steps outlined in this document, virtually every opportunity for improvement will be identified. That is, the process is thoroughly explored; the wants and needs of the users are identified, and then, as warranted, turned into functional elements of the system. The result is a central repository that is accessible to all and with the capability of significantly reducing cost and timing. The development process presented here is not a difficult one to accomplish, but does require keeping track of a lot of detail. It can therefore be quite time consuming.

New supplier / manufacturer relationship are necessary to produce products quickly, cost-effectively, and with features expected by the customer. However, the need for a new relationship is not universally accepted and endorsed. Resistance can be minimized through supplier self-assessment (such as Ford Motor Company's web-based instruments), management initiatives, and incentives. Trust and sharing are hallmarks. This strategy requires a new workplace paradigm affecting culture and people issues. Teams, extend across companies, share ideas and innovations. Decisions need to be mutually beneficial and the long-term value, for supplier and manufacturer, needs to be considered.

This project investigated the effect of carburizing carbon-potential and thermal history on the bending fatigue performance of carburized SAE 4320 gear steel. Modified-Brugger cantilever bending fatigue specimens were carburized at carbon potentials of 0.60, 0.85, 1.05, and 1.25 wt. pct. carbon, and were either quenched and tempered or quenched, tempered, reheated, quenched, and tempered. The reheat treatment was designed to lower the solute carbon content in the case through the formation of transition carbides and refine the prior austenite grain size. Specimens were fatigue tested in a tension/tension cycle with a minimum to maximum stress ratio of 0.1. The bending fatigue results were correlated with case and core microstructures, hardness profiles, residual stress profiles, retained austenite profiles, and component distortion.

The existence of the cyclic variation of the flow inside an cylinder affects the performance of the engine. Developing methods to understand and control in-cylinder flow has been a goal of engine designers for nearly 100 years. In this paper, passive control of the intake flow of a 3.5-liter DaimlerChrysler engine was examined using a unique optical diagnostic technique: Molecular Tagging Velocimetry (MTV), which has been developed at Michigan State University. Probability density functions (PDFs) of the normalized circulation are calculated from instantaneous planar velocity measurements to quantify gas motion within a cylinder. Emphasis of this work is examination of methods that quantify the cyclic variability of the flow. In addition, the turbulent kinetic energy (TKE) of the flow on the tumble and swirl plane is calculated and compared to the PDF circulation results.