Modal and Impact Simulations of a Tire in Time Domain

Tires are a key factor determining vehicle NVH performance. Tire models are usually reduced to linear modal models in the frequency domain even though the tire behaves nonlinearly in vibration and impact performance. Improving the CAE capability of vehicle NVH prediction requires an appropriately representative tire model and finite element analysis program capable of non-linear transient analysis. In this paper a detailed tire model of solid elements has been developed. Using an explicit integration finite element program, the nonlinear effects in tire modal extractions were studied.

The finite element model tire was inflated and preloaded against a flat platform with applied impulse loads to simulate the laboratory tire hammer impact tests. The tire modes in each direction were then extracted with fast Fourier transformation to compare with traditional finite element method generated modes and vehicle NVH test data. This comparison confirmed the reliability of the finite element analysis and the generated tire modes. The analysis also provided clear evidence that the fixed tire patch boundary condition caused higher predicted first vibration modes in the vertical and the steering directions than would be obtained with natural boundary conditions.

A finite element model dynamic simulation of a tire cleat impact test for a tire rolling on a drum was also correlated in both time and frequency domains with comparable tire test data. Reasonable agreement was observed.