STUDY AND CHARACTERIZATION OF NORMAL MODES IN PASSENGER VEHICLETIRES

Abstract

The transmission of vibrations in motorcycles and their perception by the passengers are fundamental in comfort analysis. Tire nonuniformities can generate selfexcitations at the rotational frequency of the wheel and contribute to the ride vibration environment. In this work a multi-body motorcycle model is built to evaluate the ride comfort with respect to tire nonuniformities. The aim is to obtain a multi-degrees-of-freedom dynamic model that includes both the contributions of the motorcycle and tire-wheel assembly structures. This representation allows the tire nonuniformities to predict the vertical force variations on the motorcycle and can be used through a root mean square acceleration evaluation for ride comfort analysis. The motorcycle model proposed is a 10-degrees-offreedom system, where each tire-wheel is a 4-degrees-of-freedom model. The tire-wheel assemblies include two types of nonuniformities: lumped mass imbalance and radial run-out. Simulations of analytical models are compared with experimental tests.