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The need for efficient space utilization has provided a framework for the design of a 248mm family of torque converters that supports a wide choice of engine and transmission combinations. The axial length of the part and its weight have been substantially reduced while the performance range has been broadened without degradation of efficiency. The new converter operates in an expanded slipping clutch mode. It significantly contributes to the performance and fuel economy improvements of related vehicles. To meet the cost target, the comprehensive lineup and the resulting complexity have required a high level of component interchangeability. During the design phase, the manufacturing core competencies were scrutinized and process redundancies eliminated, both resulting in optimization of material selection and applicable technology.

This paper presents a method for optimization design of an engine mounting system subjected to some constraints. The engine center of gravity, the mount stiffness rates, the mount locations and/or their orientations with respect to the vehicle can be chosen as design variables, but some of them are given in advance or have limitations because of the packaging constraints on the mount locations, as well as the individual mount rate ratio limitations imposed by manufacturability. A computer program, called DynaMount, has been developed that identifies the optimum design variables for the engine mounting system, including decoupling mode, natural frequency placement, etc.. The degree of decoupling achieved is quantified by kinetic energy distributions calculated for each of the modes. Several application examples are presented to illustrate the validity of this method and the computer program.

A continuously variable lift, duration and phase mechanical lift mechanism is described, as applied to the intake valvetrain of a SOHC, 4-valve per cylinder, four-cylinder production engine. Improvements in fuel economy were sought by reduction of pumping losses and improved charge preparation, and optimization of WOT torque was attempted by variation of intake valve closing angle. Adjustment of the mechanism is achieved by movement of the pivot shaft for the rocker arms. The relationship between lift, duration and phase is predetermined at the design stage, and is fixed during operation. There is considerable design flexibility to achieve the envelope of lift curves deemed desirable. The operation of the mechanism is described, as are the development procedure, testing with fixed cams, some cycle simulation, friction testing on a separate rig and dyno testing results for idle, part load and WOT.

The Frequency Response Function (FRF) is a fundamental component to identifying the dynamic characteristics of a system. FRF's have a significant impact on modal analysis and root cause analysis of NVH issues. In most cases the FRF can be easily measured, but there are instances when the measurement is unobtainable due to spatial constraints. This paper outlines a simple experimental method for obtaining a high quality input-output FRF of a structure in areas where an impact hammer can not reach during impact testing. Traditionally, the FRF in such an area is obtained by using a load cell extender with a hammer impact excitation. A common problem with this device is a double hit, that yields unacceptable results.

In this paper, a new technology for the design of silent transaxles is developed, where topography optimization is adopted and an artificial parameter called β is proposed as an objective function, representing an upper bound of the surface velocity. The strategy of the optimization is to minimize β while getting the surface velocities less than β. as the constraints. A numerical example of reducing transaxle's radiated noise by using the new optimization technology is given in the paper. In the example, an entire Ford transaxle system was modeled numerically, where most internal components were included. First a modal frequency velocity analysis was conducted. Then an acoustic power analysis based on the Acoustic Transfer Vector (ATV) was carried out. Finally, a topography optimization based on the β - method for the transaxle was performed to minimize the radiated noise.

Vehicle thermal protection is an important aspect of the overall vehicle development process. It involves optimizing the exhaust system routing and designing heat shields to protect various components that are in near proximity to the exhaust system. Reduced time to market necessitates an efficient process for thermal protection development. A robust procedure that utilizes state of the art CFD simulation techniques proactively during the design phase is described. Simulation allows for early detection of thermal issues and development of countermeasures several months before prototype vehicles are built. Physical testing is only used to verify the thermal protection package rather than to develop heat shields. The new procedure reduces the number of physical tests and results in a robust, efficient methodology.

Variable Valve Actuation (VVA) technology provides high potential in achieving high performance, low fuel consumption and pollutant reduction. However, more degrees of freedom impose a big challenge for engine characterization and calibration. In this study, a simulation based approach and optimization framework is proposed to optimize the setpoints of multiple independent control variables. Since solving an optimization problem typically requires hundreds of function evaluations, a direct use of the high-fidelity simulation tool leads to the unbearably long computational time. Hence, the Artificial Neural Networks (ANN) are trained with high-fidelity simulation results and used as surrogate models, representing engine's response to different control variable combinations with greatly reduced computational time. To demonstrate the proposed methodology, the cam-phasing strategy at Wide Open Throttle (WOT) is optimized for a dual-independent Variable Valve Timing (VVT) engine.

The use of composite materials in the automotive industry has become increasingly widespread. With this increase in use, techniques for non-destructive testing (NDT) have become more and more important. Various optical NDT inspective methods such as holography, moiré techniques, and shearography have been used for material testing. Among these methods, shearography appears to be most practical. Shearography has a simple optical setup due to its “self-referencing” system, and it is relatively insensitive against rigid-body motions. Measurements of displacement derivatives, and thus strain directly, rather than the displacement itself is achieved through this method. Therefore shearography detects defects in objects by correlating anomalies of strain which are usually easier than correlating the anomalies of the displacement itself, as in holography. To date shearography has shown potential as a NDT tool for identifying defects in small structures.

The pulse severities from various vehicle impact tests need to be assessed during the impact structure development and targeting stage to assure that the occupants can meet the injury criteria as required. The conventional method using TTZV (time to zero velocity), TDC (total dynamic crush), and G1/G2 (two stage averaged pulse) is often unable to give a quick and clear answer to the question being raised. A simple numerical tool is developed here to assess the pulse severity with a single parameter in which the severity is expressed as the amount of chest travel under a certain target restraint curve or chest A-D curve. The tool is applied to several front impact vehicle pulses to show the effectiveness. The new method developed here can be used to assess the pulse severity in an easy and objective way along with conventional parameters.

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.

Low frequency torsional vibrations can be a significant source of objectionable vehicle vibrations and in-vehicle boom, especially with changes in engine operation required for improved fuel economy. These changes include lower torque converter lock-up speeds and cylinder deactivation. This paper has two objectives: 1) Examine the effect of increased torsional vibrations on vehicle NVH performance and ways to improve this performance early in the program using test and simulation techniques. The important design parameters affecting vehicle NVH performance will be identified, and the trade-offs required to produce an optimized design will be examined. Also, the relationship between torsional vibrations and mount excursions, will be examined. 2) Investigate the ability of simulation techniques to predict and improve torsional vibration NVH performance. Evaluate the accuracy of the analytical models by comparison to test results.

The induction hardening process involves a complex interaction of electromagnetic heating, rapid cooling, metallurgical phase transformations, and mechanical behavior. Many factors including induction coil design, power, frequency, scanning velocity, workpiece geometry, material chemistry, and quench severity determine a process outcome. This paper demonstrates an effective application of a numerical analysis tool for understanding of induction hardening. First, an overview of the Caterpillar induction simulation tool is briefly discussed. Then, several important features of the model development are examined. Finally, two examples illustrating the use of the computer simulation tool for solving induction-hardening problems related to cracking and distortion are presented. These examples demonstrate the tool's ability to simulate changes in process parameters and latitude of modeling steel or cast iron.

A new multi-layer co-extruded in-color Ionomer film is developed to provide an alternative decoration process to replace paint on Dodge Neon Fascias. The Ionomer film provides a high-gloss “class-A” surface in both non-metallic and metallic colors that match the car body paint finish. Using the Ionomer film to decorate fascias reduces cost; eliminates VOCs; increases manufacturing flexibility and improves performance (weatherability and durability). The molding process consists of thermoforming a film blank and injection molding Polypropylene or TPO behind the film. The paper will include the background, the benefits, the technology development objectives, the film materials development, tooling optimization, film fascia processing (co-extrusion; thermoforming and injection molding) and validation testing of the film.

Improvement of vehicle door closure sound quality is one of the major customer wants. It is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to design for a specific sound target. In this paper, a CAE tool is developed based on transient FEA and BEA for the analysis of structural-borne vehicle door closure sound quality in the low frequency range (up to 300Hz). Design sensitivity analysis (DSA) are performed for investigating effects of major design variable changes on the door closing sound quality. A SUV model was studied to validate the simulation results and to demonstrate the capability of the developed CAE tool for providing design guidelines on door closing sound quality.

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.

The automotive industry is rapidly implementing computer simulation in every aspect of their processes mainly to decrease the time required to bring new models to market. Computer simulation can also be used to reduce the cost of vehicle development and manufacturing. A major portion of the manufacturing cost associated with automotive stamping lies in the process design, build and tryout of production dies and in automation of the transfer equipment. Press home-line tryout is largely a trial-and-error process relying heavily on the skills and experience of tool and die makers. To reduce this dependence on human skills and effort, press-line simulation can be effectively utilized to verify the design accuracy thereby reducing the changes needed to rework the production die/tool. The entire press-line with all its complete accessories can be modeled and checked for design errors similar to the try-out conducted in the production plant.

This paper identifies the difference in powertrain cooling system content levels using a nominal and a +3 Standard deviation maximum temperature design approach. Variation simulation analysis tools are used along with a 1-D cooling system performance model to predict resulting temperature distribution for different combinations of input variable populations. The analysis will show differential in powertrain cooling system content, mass, and impact to fuel economy for a nominal vs. +3 sigma design approach.

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.

Most products are designed to operate for a long period of time, and in such case, life testing is a relatively lengthy procedure. Lengthy tests tend to be expensive and the results become available too late to be of much use. To reduce the experimental cost significantly and provide an efficient tool to assess the life distribution for highly reliable product, a step-stress accelerated test (SSAT) was developed. An example of a rear suspension aft lateral link is used to validate the SSAT method.