Characterising non-linear elements with free-free and fixed boundary conditions for dynamic substructuring

Abstract

In the context of dynamic substructuring applied to the automotive field, a crucial aspect for determining the noise property of a vehicle is the evaluation of the transfer behaviour of the rubber elements connecting the different components of a car. The goal of this research is to extract the frequency dependent dynamic stiffness for different models of rubber bushings presenting a similar architecture. In particular we will compare two different methods for characterising the dynamic behaviour of non-linear elements using the virtual point transformation. Firstly, a free-free measurement with hammer impacts will be performed. Here, particular attention will be given to the weighting matrices of the virtual point transformation to explore how those terms could improve the method. Secondly, on the same bushings, we modify the experiment by clamping the rubber mounts to the ground and creating fixed boundary conditions. Here, the system is excited both with hammer impacts and shaker excitation and we will highlight comparable results with the previous experiment. The different approaches will be compared in terms of accuracy, experimental effort, and numerical stability.