A Comparison of Two Sub-structuring Techniques for Representing the Modal Properties of Tires

Abstract

Different numerical sub-structuring techniques for the representation of tire modal behavior have been developed in the past 20 years. By using these numerical techniques reduced dynamic models are obtained which can not only be used for internal studies but also be provided to the automobile industry and linked to reduced dynamic vehicle models in order to optimize the coupled vehicle-tire response for noise vibration and harshness purposes. Two techniques that have been developed in a custom-made finite element code are presented: 1) the component mode synthesis type models for which the wheel center interface is free and 2) the Craig and Bampton type models for which the wheel center interface is fixed. For both techniques the interface between the tire and the ground is fixed. The choice of fixed or free wheel center boundary condition is arbitrary. In this paper we will compare the formulation of these two numerical methods, and we will show the equivalency of both methods by showing the results obtained in terms of frequency and transfer functions. We will show that the two methods are equivalent in principle and the reduced dynamic models can be converted from one to the other. The advantages-disadvantages of each method will be discussed along with a comparison with experimentally obtained results.

Tire data for TMPT: the point of view of the tire industry

“…Application of the FE method to tire modal analysis is particularly well adapted [6]: first, because modal density is low at low frequencies (below 300 Hz) and secondly, only two interfaces are present (tire/wheel and tire/ground), which simplifies the possible boundary conditions.…”