Modelling vibration transmission through a car's damper and top mount strut

© Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved. Structure-borne road noise in cars originates from vibrations generated at the tyre-road interface that propagate through the suspension into the car's body. Manufacturers require accurate tools to predict and therefore mitigate road noise in the cabin. However, the process is complicated by the presence of nonlinear components in the suspension. This paper presents an investigation into the dynamic behaviour of the damper and top mount, which constitute the most strongly nonlinear transmission path in a typical car suspension, for frequencies up to 300 Hz. Experiments have been conducted on the damper and top mount individually to quantify their nonlinear characteristics. When coupled together, the coherence of transmitted vibrations was observed to decrease at frequencies above 50 Hz, suggesting that nonlinear processes are significant in the vertical strut. Published physical models of each component have been fitted to experimental data and shown to perform well over the low audio frequency range. The models have been combined to form a nonlinear suspension strut model that predicts the interaction of the damper and top mount; results from the model are presented and compared with experimental measurements. The development of a nonlinear strut model, validated for low audio frequencies, is a novel contribution that represents a step towards a full suspension model suitable for structure-borne road noise analyses