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Vibration and sound radiation characteristics of bead-stiffened panels are investigated. Rectangular panels with different bead configurations are considered. The attention is focused on various design parameters, such as orientation, depth, and periodicity, and their effects on equivalent bending stiffness, modal density, radiation efficiency and sound transmission. A combined FEA-SEA approach is used to determine the response characteristics of panels across a broad frequency range. The details of the beads are represented in fine-meshed FEA models. Based on predicted surface velocities, Rayleigh integral is evaluated numerically to calculate the sound pressure, sound power and then the radiation efficiency of beaded panels. Analytical results are confirmed by comparing them with experimental measurements. In the experiments, the modal densities of the panels are inferred from averaged mechanical conductance.

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.

NVH targets for future vehicles are often defined by utilizing a competitive benchmarking vehicle in conjunction with an existing production and/or reference vehicle. Mode management of full vehicle modes is one of the most effective and significant NVH strategies to achieve such targets. NVH dynamic characteristics of a full vehicle can be assessed and quantified through experimental modal testing for determination of global body mode resonance frequency, damping property, and mode shape. Major body modes identified from full vehicle modal testing are primarily dominated by the vehicle's body-in-white structure. Therefore, an estimate of BIW modes from full vehicle modes becomes essential, when only full vehicle modes from experimental modal testing exist. Establishing BIW targets for future vehicles confines the fundamental NVH behavior of the full vehicle.

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.

An accurate air flow rate model is critical for high-quality air-fuel ratio control in Spark-Ignition engines using a Three-Way-Catalyst. Emerging Variable Valve Timing technology complicates cylinder air charge estimation by increasing the number of independent variables. In our previous study (SAE 2004-01-3054), an Artificial Neural Network (ANN) has been used successfully to represent the air flow rate as a function of four independent variables: intake camshaft position, exhaust camshaft position, engine speed and intake manifold pressure. However, in more general terms the air flow rate also depends on ambient temperature and pressure, the latter being largely a function of altitude. With arbitrary cam phasing combinations, the ambient pressure effects in particular can be very complex. In this study, we propose using a separate neural network to compensate the effects of altitude on the air flow rate.

Liquid spray applied damping materials have potential advantages over conventional sheet damping materials in automotive body panel vibration applications. In order to understand the acoustical impact, a laboratory based NVH study was conducted to compare the damping and stiffness performance characteristics of various sprayable damping materials versus the production damping treatment. Based on this comparison, a criteria was developed to select potentially viable sprayable damping materials for vehicle testing. In-vehicle tests were also performed and compared to the laboratory findings to understand how well the results correlate. This paper discusses a criteria for selecting sprayable damping materials based on bench-top tests for vehicle applications, and the potential benefits of sprayable materials.

Transmission mounts are usually tested as an assembly and typically only translational stiffnesses are provided. The torsional stiffness of the assembly is traditionally estimated based on experience in load simulation and analysis. This paper presents a procedure to estimate the torsional stiffness of the transmission mount assembly by using the test data. The effects of the torsional stiffness on the simulation results are also discussed.

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.

In September 2003, the Mercedes Car Group set another milestone by introducing the fifth generation of automatic transmissions developed and manufactured in-house since 1960. The world's first 7-speed automatic transmission 7G-TRONIC is featured in the Mercedes-Benz S, SL, CL and E-Classes with V8 gasoline engines. Deduced from the demands of the requirement specifications, the 5-speed automatic transmission was decisively improved; the result is a clear increase in spontaneity, agility, fuel economy, and driving comfort for the customer. And because of the harmony between the vehicle and its powertrain, excellent results in the areas of performance, reduced emissions, comfort, and acoustics are obtained.

For the 2003 model year DaimlerChrysler Corporation (DCC) will introduce an all-new 5.7L V8 truck engine manufactured at the new Saltillo II Engine Plant (SEPII) in Saltillo, Mexico. The product will debut in the new RAM series of pick-up trucks and marks the return of the hemispherical combustion chamber architecture. This paper covers the engine design features, simulation methods, development, and manufacturing processes. Also reviewed are the project objectives and the organizational processes used to manage and deliver the program.

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.

With the ever increasing popularity of SUV automobiles, studies involving driveline specific problems have grown. One prevalent NVH problem is axle whine associated with the assembled motion transmission error (MTE) of an axle system and the corresponding vibration/acoustic transfer paths into the vehicle. This phenomenon can result in objectionable noise levels in the passenger compartment, ensuing in customer complaints. This work explores the methodology and test methods used to diagnose and solve a field axle whine problem, including the use of cab mount motion transmissibility path analysis, running modes and a detailed MTE best-of-the-best (BOB)/worst-of-the-worst (WOW) study. The in-vehicle axle whine baseline measurements including both vehicle dynamometer and on-road test conditions, along with the countermeasures of axle whine fixes are identified and presented in this paper.

Tailor welded steel blanks have long been applied in stamping of automotive parts such as door inner, b-pillar, rail, sill inner and liftgate inner, etc. However, there are few known tailor welded aluminum blanks in production. Traditional laser welding equipment simply does not have the capability to weld aluminum since aluminum has much higher reflectivity than steel. Welding quality is another issue since aluminum is highly susceptible to pin holes and undercut which leads to deterioration in formability. In addition, high amount of springback for aluminum panels can result in dimension control problem during assembly. A tailor-welded aluminum blank can help reducing dimension variability by reducing the need for assembly. In this paper, application of friction stir and plasma arc welded blanks on a liftgate inner will be discussed.

Over 250 million tires are scrapped in the United States each year. Tires have been a problematic scrap because they have been designed to resist destruction, and have a tendency to float upwards in landfills. Improper storage has resulted in tire fires1--an even more problematic environmental concern than unsightly piles which can serve as breeding grounds for insect vectors. A better solution is to recover materials for use in new components. Not only does this resolve the landfill issue, but it also serves to conserve resources, while returning an economic benefit to society. This paper traces the introduction of tire material recovery at NRI Industries and DaimlerChrysler Corporation (DCC), the development of the infrastructure and materials, and the launch of the Jeep Grand Cherokee thermoplastic elastomer (TPE) radiator seals, comprised of post consumer tire crumb.

In this paper, mechanism of fastened joints is described; numerical analyses and testing calibrations are conducted for the possible simplified finite element simulation approaches of the joints; and the best simplified approach is recommended. The approaches cover variations of element types and different ways that the joints are connected. The element types include rigid elements, deformable bar elements, solid elements, shell elements and combinations of these element types. The different ways that the joints are connected include connections of one row of nodes, two row of nodes and alternate nodes in the first and second rows. These simplified simulation approaches are numerically evaluated on a joint of two plates connected by a single fastener. The fundamental loads, bending with shear, shear and tension are applied in the numerical analyses. A detailed model including contact and clamp load are analyzed simultaneously to provide “accurate results”.

Typical automotive sound package components are usually characterized by their absorption coefficients and their acoustic power-based insertion loss. This insertion loss (IL) is usually obtained by subtracting the transmission loss (TL) of a bare flat steel plate from the TL of the same plate covered with the trim material. While providing useful information regarding the performance of the component, air-borne insertion loss is based solely on acoustic excitations and thus provides very little information about the structure-borne performance of the component. This paper presents an attempt to introduce a standard procedure to define the power-based structure-borne insertion loss of sound package components. A flat steel plate is excited mechanically using a shaker. Different carpet constructions are applied on the plate and tested. Based on velocity measurements, a force transducer and intensity probe, the mechanical input and the acoustic radiated power are obtained.

This paper describes the performance improvement and cost savings achieved by the Stamping Technology Department at DaimlerChrysler Corporation (Chrysler group), in migrating from Unix workstations with RISC technology to Linux PCs with Intel Pentium technology. Performance comparisons of various engineering applications running on these two system configurations are analyzed. The major aspects such as hardware configuration, operating system, software availability, compatibility, reliability, accuracy and consistency of simulation results are discussed. The improvement in computing speed and deviations in simulation results between MPP LS-Dyna and SMP LS-Dyna are presented.

The objective of this paper is to investigate the effect of stamping process on oil canning and dent resistance performances of an automotive roof panel. Finite element analysis of stamping processes was carried out using LS-Dyna to obtain thickness and plastic strain distributions under various forming conditions. The forming results were mapped onto the roof model by an in-house developed mapping code. A displacement control approach using an implicit FEM code ABAQUS/Standard was employed for oil canning and denting analysis. An Auto/Steel Partnership Standardized Test Procedure for Dent Resistance was employed to establish the analysis model and to determine the dent and oil canning loads. The results indicate that stamping has a positive effect on dent resistance and a negative effect on oil canning performance. As forming strains increase, dent resistance increases while the oil canning load decreases.

Springback study on a Dodge Ram fender outer panel is detailed in this paper. A simple measurement fixture is designed for the panel, wherein non-contact laser scan technology is applied The measurement data are compared with the original CAD design surface and deviation contour maps are obtained. Consistency of measurement is studied at different sections among three samples. Details of FEA simulations are outlined. The comparison between measurement and simulation prediction is summarized. A method to describe the consistency of measurement and the accuracy of simulation prediction is proposed. The targets for measurement consistency and simulation accuracy are verified. A sensitivity analysis is also performed to investigate various simulation input parameters.

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.