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Two beam elements chassis/suspension models with rigid vehicle body representation and finite element tires were studied under proving ground conditions. The only difference between the two models was that one used flexible beam elements and the other used rigid beams. Several proving ground road surfaces were modeled and used in the analysis, including a washboard road surface, a Belgian block type track and a pothole track,. Also analyzed were the low speed driveway-ramp and (relatively) high speed lane-change cases. The proving ground simulation results, and system compliance results as well, were compared between the two models. The differences revealed the importance and necessity of using finite element model (even just using deformable beam elements) to include the component flexibility in conducting vehicle chassis/suspension dynamic analysis.

A tire model and its interface performance with road surface plays a major role in vehicle dynamics analysis and full vehicle real time proving ground simulations. The successful tire model must be able to support the vehicle weight, provide vehicle control and stability, transfer various forces and torques from road/tire interaction to a vehicle chassis/ suspension system. The dynamic effects in terms of tire stiffness and internal damping characteristics in impact loading conditions must also be accounted for in the model. A Finite Element Analysis (FEA) tire model is established and its performance is validated using LS/DYNA3D* analysis code simulating the radial and lateral static stiffness test conditions, the one-meter dynamic free-drop test condition and the rolling cornering stiffness. The analysis results are compared with available test data and a generic empirical formula.

Rubber isolators and bushings are very important components for vehicle performance. However, one often finds it is difficult to get the dynamic properties to be readily used in CAE analysis, either from suppliers or from OEM's own test labs. In this paper, the author provides an analytical method to obtain the dynamic stiffness of an exhaust isolator, using ABAQUS and iSight, with tested or targeted isolator static stiffness information. The analysis contains two steps. The first step is to select the (rubber/EPDM) material properties for the FE isolator model by matching the static stiffness with either the targeted spring rate (linear or nonlinear) or the (tested) load / deflection curve. The second step is to perform dynamic analysis on the statically “validated” FE isolator model to obtain its dynamic properties.