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This paper outlines a newly developed method for predicting the coupled response of structures from their uncoupled forced responses without having to know the forces acting on such structures. It involves computing the forced response of originally uncoupled structures with several mass loadings at a potential coupling point. The response data obtained from such computations is then used to predict the coupled response. The theory for discrete linear systems is outlined in the paper and a numerical example is given to demonstrate the validity, advantages and limitations of the method. The method is primarily devised to obtain coupled response of linear dynamic systems from independent and uncoupled analytical simulations. Its application significantly decreases computation time by reducing the simulation model size and is excellent for “what if” scenarios where a large number of simulations would otherwise be necessary.

A technique which uses Finite Element Analysis (FEA) to derive important parameters involved in SEA (Statistical Energy Analysis) is discussed. Application of the method to a variety of structures has yielded good correlation with experimentally generated results. SEA parameters including Coupling Loss Factors (CLFs), modal densities, and subsystem equivalent masses were obtained. The technique has the advantage of incorporating structural detail to enhance SEA predictions at lower frequencies where global modes are important, and it can be applied early in the design phase since no hardware is required. With this study, SEA is more readily applied to structure-borne noise problems in vehicles.

The Energy Flow Method (EFM), which is based on a Finite Element Analysis (FEA) model and its modal frequency response solution is presented in this paper. The energy and power for each subsystem are the primary response and excitation parameters as in the Statistical Energy analysis (SEA) method. This gives a broad-brush prediction by averaging over both frequency and spatial domain. This prediction is useful when uncertainties exist in the model. The FEA model is used to capture the geometry detail, which is critical in mid-frequency vibration. As an example, a five-plate system is studied using various methods, including traditional FEA, SEA and EFM. The last one has been implemented in MSC/NASTRAN. A discussion is given to understand the limitation of SEA and FEA application in mid frequency response.

Reducing the high cost of hardware testing with analytical methods has been highly accelerated in the automotive industry. This paper discusses an analytical model to simulate the driveline boom test for the transverse engine with all wheel drive configuration on a front-wheel drive base (TFWD/AWD). Driveline boom caused by engine firing frequency that excites the bending mode of the propeller shaft becomes a noise and vibration issue for the design of TFWD/AWD driveline. The major source of vibrations and noise under the investigation in this paper is the dominant 3rd order engine torque pulse disturbance that excites the bending of the propeller shaft, the bending of the powertrain and possible the bending of the rear halfshaft. All other excitation sources in this powertrain for a 60° V6 engine with a pushrod type valvetrain are assessed and NVH issues are also considered in this transient dynamic model.

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.

As automobile power needs increase 42-volt electrical systems are being proposed for use in consumer vehicles. One concern when using these new systems is the corrosion resistance of these components, especially in underhood environments. Corrosion is an electrochemical phenomenon and as such can be altered (increased or decreased) by the application of an external current or voltage. Although unintentional, the use of a higher voltage electrical system has the ability to increase corrosion through its normal use. This program evaluated the impact of corrosion on electrical components powered by 14 and 42-volt DC systems. Accelerated corrosion test findings suggested that 42-volt systems may be more susceptible to corrosion, but without proper environmental shielding both supply system can have unacceptable degradation.

This report describes the use of meshfree methods for response and design sensitivity calculations within structural reliability analysis when geometric shape is a random variable. Brief descriptions of meshfree methods and advanced probabilistic methods are provided. An existing interface between the probabilistic analysis and traditional finite element method is modified to allow the use of meshfree methods for response and design sensitivity calculations within the probabilistic analysis routine. Two examples that treat design shape as a random variable are presented to assess the accuracy and use of meshfree methods for reliability analysis.

High interest is expressed in using analytical models to eliminate costly driveline tests used to determine the stresses produced in the driveshaft and driveline during resonant operating conditions. This paper discusses an analytical model to simulate the driveline-bending integrity, test procedure. Three major subsystems are modeled in this analytical approach, namely powertrain, rear axle, and driveshaft. Imbalance masses were added on the driveshaft to induce the whirl motion of the driveshaft. The combination of nonlinear Multi-body System Simulation (MSS) and linear Finite Element Analysis (FEA) in the time domain was employed for the evaluation of the dynamic interaction between several parts.

Several methods are currently used to enforce motion in different types of noise and vibration models. Experimentally based FRF models often use a matrix inversion technique to enforce motion. In finite element models, the large mass method is one that is very commonly used. A literature review has shown few guidelines for determining the size of these large masses. In this paper, the relationship between the matrix inversion technique and the large mass method is derived. From this relationship, conditions necessary for these large mass FEM models to converge to the same answers as the matrix inversion technique are derived. These conditions are then used to develop a criterion for determining a smallest possible large mass. Results from a simple model are presented to demonstrate the criterion.

Today's competitive market requires new products to have extremely high Quality; customer expectation demands it. Testing, Validation, Setting Requirements, Failure Mode & Effect Analysis (FMEA), and Design Reviews by themselves do not improve a product; they only provide information that has to be translated into Design/Manufacturing & Service tasks. The quality of these tasks determines how well the new product will perform at its introduction. This paper outlines a generic Development Process through the use of an automotive example for a Door Glass Guidance Mechanism. This process includes the fundamental steps involving recommendations for setting requirements, benchmarking, and a methodology on how to design in requirements through the use of analytical and experimental tools to create Robust Designs. Also included are examples of Validation and Assessment Plans that are requirement driven.

PEM Fuel Cell technology has been advancing rapidly during the last several years as evidenced by various vehicle demonstrations by the major automotive companies. As the development continues to bring hardware to automotive system level solutions, many engineering challenges arise. This paper will deal with two (2) of these areas from an automotive system level perspective: Thermal Management and the Fuel Cell Stack. Both of these sub-system areas are critical to the success of the technology in meeting the requirements of tomorrow's automotive customer.

A method is presented to process random vibration data from a complete road durability test environment as stationary segments and then develop test profiles based on fatigue content of their power spectral densities. Background is provided on existing techniques for estimating fatigue damage in the frequency domain. A general model for stress response to acceleration is offered to address the vibration test's requirement for acceleration data and the fatigue prediction method's requirement for stress data. With these tools, the engineer can extend test correlation beyond failure modes to include retention of estimated fatigue damage. Recommendations allow for test time compression from editing and improve existing exaggeration methods.

General Motors Powertrain Division has developed the next generation big block V8 engine for introduction in the 1996 model year. In addition to meeting tighter emission and on-board diagnostic legislation, this engine evolved to meet both customer requirements and competitive challenges. Starting with the proven dependability of the time tested big block V8, goals were set to substantially increase the power, torque, fuel economy and overall pleaseability of GM's large load capacity gasoline engine. The need for this new engine to meet packaging requirements in many vehicle platforms, both truck and OEM, as well as a requirement for minimal additional heat rejection over the engine being replaced, placed additional constraints on the design.