ABSTRACT
This chapter provides a nonlinear material model that accounts for both frequency and amplitude dependent effects and allows predicting the dynamic stiffness of rubber isolators when implemented in a commercial Finite Element (FE) code. A time domain non-linear model is presented to predict the dynamic stiffness of rubber isolators using a FE code. Viscoelastic response is modelled via a fractional derivative model, while amplitude dependency is considered through Coulomb friction elements. Rubber compound frequently has carbon black filler added, consisting of very small carbon particles forming agglomerates within the rubber material. A complex problem is faced when it comes to implement the fractional derivative Zener model that represents both the elastic and frequency dependent characteristics of rubber. As far as the non-linear model is concerned, the whole model is composed of a fractional derivative Zener mesh and three elastoplastic meshes. The simplified methodology has proved to be an efficient method to estimate the dynamic stiffness of bushings.
