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Since road roughness is an important source of vehicle vibration, a system model for NVH analysis requires a tire model which accurately predicts spindle response to road input. Most tire models currently used in the auto industry do not meet this requirement, because they are based on static stiffness of the tire and do not produce realistic response to input at the patch. This paper investigates a new modal tire model with patch input capability as a component within a vehicle system model. Comparisons are also presented between the behavior of the new tire model and a conventional spring model. To validate the performance of the tire model for NVH analysis, simulated vehicle responses to bump input are compared to chassis roll test results. Good correlation between the model prediction and the chassis roll measurements is observed.

This paper concerns the finite element method as applied to the analysis of small oscillations about the non-linear equilibrium position in elastomeric components. The capability, which was developed at Ford, has been implemented in the general-purpose finite element program, MARC. The material behavior is treated by use of a modified form of the constitutive equations derived by Lianis [Proc. Fourth International Congress on Rheology, Pt. 2, 109 (1965)] using the finite linear viscoelasticity theory of Coleman and Noll [Rev. Mod. Phys., 33 239 (1961)]. In order to establish numerical accuracy, program predictions are compared with a closed form solution for the torsional and axial vibrations in a cylinder under axial and twisting pre-loads: differences between the finite element solutions and exact results are less than two (2) percent.