SAE International Finite Element Overlay Technique for Predicting the Payne Effect in a Filled-Rubber Cab Mount 2012-01-0525

Filled-rubber is widely used in automotive applications for noise and vibration isolation. The inherent material characteristics of filled-rubber make it suitable for these applications, but its complicated nonlinear behavior under both static and dynamic loading can make material modeling a challenge. This paper presents a two-element overlay technique to capture the nonlinear vibration amplitude dependency of a carbon-filled rubber material commonly referred to as the "Payne Effect." This overlay technique is practically applied to predict the nonlinear dynamic stiffness and damping loss characteristics of a carbon-filled rubber body cab mount component from a body-on-frame vehicle calculated as a function of large static pre-strain, dynamic excitation frequency, and small dynamic strain amplitude in a single analysis. The first layer of elements is assigned a joint hyperelastic and linear viscoelastic material model that captures the pre-strain and frequency dependent behavior of the rubber material. While the second layer of elements, which is superimposed upon the first layer, is assigned a multi-linear kinematic hardening plasticity material model that captures the hysteresis and amplitude dependency of the material when subjected to dynamic loads. The two-element overlay technique is implemented using commercially available finite element software and is validated using physical test results. The technique accurately predicts the nonlinear dynamic stiffness of the filled-rubber component showing excellent correlation to physical test results while limiting model size and complexity as compared to other approaches.