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Once the design of a door sheetmetal and accessories is confirmed, the acoustics of the door system depends on the sound package assembly. This essentially consists of a watershield which acts as a barrier and a porous material which acts as an absorber. The acoustical performance of the watershield and the reverberant sound build-up in the door cavity control the performance. This paper discusses the findings of a design study that was developed based on design of experiments (DOE) concepts to determine which parameters of the door sound package assembly are important to the door acoustics. The study was based on conducting a minimum number of tests on a five factor - two level design that covered over 16 different design configurations. In addition, other measurements were made that aided in developing a SEA model which is also compared with the findings of the results of the design study.

Studies in an Angular Stretch Bend Test (ASBT) have demonstrated that the failure location moves from the side wall to punch nose area. This occurs as the R/T ratio decreases below a certain limit and applies to most low carbon steels with the exception of Dual Phase (DP) steels. Such behavior in DP steels indicates that bending effects have a severe impact on the formability of DP materials. Therefore, the traditional criterion using the forming limit curve (FLC) is not suitable to assess the formability at punch radius areas for DP steels due in part to its uniqueness of unconventional microstructures. In this paper, a new failure criterion, ‘Bending-modified’ FLC (BFLC), is proposed by extending the traditional FLC using the “Stretch Bendability Index” (SBI) concept for the stretch bendability assessment.

A simple strategy for building lightweight automobile body-in-whites (BIWs) is developed and discussed herein. Because cost is a critical factor, expensive advanced materials, such as carbon fiber composites and magnesium, must only be used where they will be most effective. Constitutive laws for mass savings under various loading conditions indicate that these materials afford greater opportunity for mass saving when used in bending, buckling or torsion than in tensile, shear or compression. Consequently, it is recommended that these advanced materials be used in BIW components subject to bending and torsion such as rails, sills, “A-B-C” pillars, etc. Furthermore, BIW components primarily subject to tension, compression, or shear, such as floor pans, roofs, shock towers, etc., should be made from lower cost steel. Recommendations for future research that are consistent with this strategy are included.

The 45RFE is a new generation electronically controlled rear wheel drive automatic transmission. It employs real-time feedback, closed-loop modulation of shift functions to achieve outstanding shift quality and to meet demanding durability goals. It uses no shift valves; all friction element applications are effected with high-flow electro-hydraulic solenoid valves. A unique gear train arrangement of three planetary carriers allows all sun gears and annulus gears to have the same number of teeth respectively and use a common pinion gear in all carriers, resulting in significant manufacturing simplification. The three-planetary system is designed for four forward ratios of 3.00, 1.67, 1.00 and 0.75 and one reverse gear ratio equal to the low gear ratio. A fifth ratio of 1.50 is used only in certain kick-down shift sequences for highway passing. A sixth forward ratio, an additional overdrive ratio of 0.67, is available in the hardware.

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.

For the purposes of analyzing and understanding the general effects of a set of different vehicle attributes on overall crash outcome a fleet model is used. It represents the impact response, in a one-dimensional sense, of two vehicle frontal crashes, across the frontal crash velocity spectrum. The parameters studied are vehicle mass, stiffness, intrusion, pulse shape and seatbelt usage. The vehicle impact response parameters are obtained from the NCAP tests. The fatality risk characterization, as a function of the seatbelt use and vehicle velocity, is obtained from the NASS database. The fatality risk is further mapped into average acceleration to allow for evaluation of the different vehicle impact response parameters. The results indicate that the effects of all the parameters are interconnected and none of them is independent. For example, the effect of vehicle mass on fatality risk depends on seatbelt use, vehicle stiffness, available crush, intrusion and pulse shape.

A statistical theory is used to quantify the amount of information transmitted from a transducer (i.e., accelerometer) to the air bag controller during a vehicle crash. The amount of information relevant to the assessment of the crash severity is evaluated. This quantification procedure helps determine the effectiveness of different testing conditions for the calibration of sensor algorithms. The amount of information in an acceleration signal is interpreted as a measure of the ability to separate signals based on parameters that are used to assess the severity of an impact. Applications to a linear spring-mass model and to actual crash signals from a development vehicle are presented. In particular, the comparison of rigid barrier (RB) and offset deformable barrier (ODB) testing modes is analyzed. Also, the performance of front-mounted and passenger compartment accelerometers are compared.

Laminated steel sheets sandwiched with a polymer core are increasingly used for automotive applications due to their vibration and sound damping properties. However, it has become a major challenge in finite element modeling of laminated steel structures and forming processes due to the extremely large differences in mechanical properties and in the gauges of the polymer core and the steel skins. In this study, circular cup deep drawing and V-bending experiments using laminated steels were conducted in order to develop a modeling technique for laminate forming processes. The effectiveness of several finite element modeling techniques was investigated using the commercial FEM code LS-Dyna. Furthermore, two production parts were selected to verify the modeling techniques in real world applications.

It is often necessary to dynamically test a big vehicle part such as a rail tip at component level in high speed. Such a big part can be crush tested dynamically using two sled carriers. The methodology is shown and discussed here, and equations are developed to help determine required parameters such as sled velocity and weights. Test results using a truck rail tip are shown and compared to full vehicle test results for correlation.

Truck frame structural performance of body on frame vehicles is greatly affected by crossmember and joint design. While the structural characteristics of these joints vary widely, there is no known tool currently in use that quickly predicts joint stiffness early in the design cycle. This paper will describe a process used to evaluate the structural stiffness of frame joints based on research of existing procedures and implementation of newly developed methods. Results of five different joint tests selected from current production body-on-frame vehicles will be reported. Correlation between finite element analysis and test results will be shown. Three samples of each joint were tested and the sample variation will be shown. After physical and analytical testing was completed, a Design of Experiments approach was implemented to evaluate the sensitivity of joints with respect to gauge and shape modification.

This paper describes a lightweight magnesium intensive automobile body structure concept developed at DaimlerChrysler to support a high fuel-efficiency vehicle project. This body structure resulted in more than 40% weight reduction over a conventional steel structure while achieving significantly improved structural performance as evaluated through CAE simulations. A business case analysis was conducted and showed promising results. One concept vehicle was built for the purpose of demonstrating concept feasibility. The paper also identifies areas for further development to enable such a vehicle to become a production reality at a later time.

This paper deals with the effects of various approaches for modeling of strain rate effects for mild and high strength steels (HSS) on impact simulations. The material modeling is discussed in the context of the finite element method (FEM) modeling of progressive crush of energy absorbing automotive components. The characteristics of piecewise linear plasticity strain rate dependent material model are analyzed and various submodels for modeling of impact response of steel structures are investigated. The paper reports on the ranges of strains and strain rates that are calculated in typical FEM models for tube crush and their dependence on the material modeling approaches employed. The models are compared to the experimental results from drop tower tests.

During the design process for a vehicle, the CAD surface geometry becomes available at an early stage so that numerical assessment of aerodynamic performance may accompany the design of the vehicle's shape. Accurate prediction requires open grille models with detailed underhood and underbody geometry with a high level of detail on the upper body surface, such as moldings, trim and parting lines. These details are also needed for aeroacoustics simulations to compute wall-pressure fluctuations, and for thermal management simulations to compute underhood cooling, surface temperatures and heat exchanger effectiveness. This paper presents the results of a significant effort to capitalize on the investment required to build a detailed virtual model of a pickup truck in order to simultaneously assess performance factors for aerodynamics, aeroacoustics and thermal management.

In automotive industry, all passenger vehicles are treated with damping materials to reduce structure borne noise. The effectiveness of damping treatments depends upon design parameters such as choice of damping materials, locations and size of the treatment. This paper proposes a CAE (Computer Aided Engineering) methodology based on finite element analysis to optimize damping treatments. The developed method uses modal strain-energy information of bare structural panels to identify flexible regions, which in turn facilitates optimization of damping treatments with respect to location and size. The efficacy of the method is demonstrated by optimizing damping treatment for a full-size pick-up truck. Moreover, simulated road noise performances of the truck with and without damping treatments are compared, which show the benefits of applying damping treatment.

In automotive testing, a chassis dynamometer is typically used, during cell testing, to evaluate vehicle performance by simulating actual driving conditions. The use of indoor cell testing has the advantage of running controlled tests where the cell temperature and humidity and solar loads can be well controlled. Driving conditions such as vehicle speed, wind speed and grade can be also controlled. Thus, repeated tests can be conducted with minimum test variations. The tractive effort required at the wheels of a vehicle for a given set of operating parameters is determined by taking into account a set of variables which affect vehicle performance. The forces considered in determination of the tractive effort include the constant friction force, variable friction force due to mechanical and tire friction, forces due to inertia and forces due to aerodynamic and wind effects. In addition, forces due to gravity are considered when road grades are simulated.

Buffeting is a wind noise of high intensity and low frequency in a moving vehicle when a window or sunroof is open and this noise makes people in the passenger compartment very uncomfortable. In this paper, side window buffeting was simulated for a typical SUV using the commercial CFD software Fluent 6.0. Buffeting frequency and intensity were predicted in the simulations and compared with the corresponding experimental wind tunnel measurement. Furthermore, the effects of several parameters on buffeting frequency and intensity were also studied. These parameters include vehicle speed, yaw angle, sensor location and volume of the passenger compartment. Various configurations of side window opening were considered. The effects of mesh size and air compressibility on buffeting were also evaluated. The simulation results for some baseline configurations match the corresponding experimental data fairly well.

Advanced material modeling was conducted to describe the thermal-mechanical behavior of Boron Steel during hot stamping, a process in which blanks at 900 °C are formed and quenched between cold dies. Plastic deformation, thermal dilatation and phase transformation were incorporated in the constitutive model and a user-defined subroutine was developed to interface with LS-DYNA. Simulation was conducted on the hot stamping process of a door intrusion beam to gain insight into the physics of the process. Results showed significant influence of the thermal cycle on final product. It was also demonstrated that the program developed can be used as an early feasibility tool to determine baseline processing parameters and to detect potential defects in products without physical prototyping.

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.

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.

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.