Indoor Vibration Testing for High-Frequency Modal Characterization of Tyres

Abstract

The driver subjective perception of a vehicle is strongly determined by its Noise, Vibration and Harshness (NVH) behavior. Consequently, the NVH performance has become an important design and marketing criterion for vehicle manufacturers. The low-frequency (0–500Hz) noise and vibration perceived by a passenger are mainly determined by the dynamic behavior of rolling tyres. Besides the increasing awareness for the problems associated with road traffic noise has lead to the demand for more quiet tyres and road surfaces. Computer aided engineering tools play an important role for improving the vehicle vibration behavior at the earliest step of the design. In order to carry out precise modeling of the vehicle and its subsystems, an accurate tyre model is a key element in predicting the performance of the vehicle system with respect to ride comfort, NVH, durability, safety (braking manoeuvre) and tyre/road interaction. To obtain the best possible performance from a tyre model, a number of different measurements are required to support the tyre model parameter identification process. Although tyre vibration and noise behavior has been studied for several decades, there are still some missing links in the process of accurately predicting and controlling the overall tyre/road noise and vibration linked to the difficulty of performing modal testing on a tyre when rotating. This paper deals with the main test benches, experimental activities and modal analysis techniques available nowadays for characterizing the dynamic behavior of a static (unloaded tyre on a fixed hub and loaded tyre on a fixed hub) and a rotating tyre under different boundary conditions. The main results arising from modal analysis of a static and dynamic test on a tyre are highlighted and compared. In particular the effect of rolling speed, inflation pressure, preload, temperature and excitation amplitude on the dynamic response of a rolling tyre will be discussed.