Methods for Measuring and Predicting Fatigue Life of Rubber Mounts of Vehicle Powertrain

Abstract

A fatigue experiment is carried out for a rubber dumbbell cylindrical specimen and a rubber mount of vehicle powertrain. The dumbbell cylindrical specimen and the mount for vehicle powertrain are made of filled natural rubbers with the same formula. The calculation method for three damage parameters to estimate fatigue of rubbers is described and discussed. The damage parameters include strain energy density, maximum principal Green-Lagrange strain and effective stress. Based on the measured fatigue life data of dumbbell cylindrical specimen, three models using different damage parameters to predict rubber fatigue life is presented. The fatigue life of the mount predicted by the three models is estimated and is compared with the experimental fatigue life. The fatigue life calculated using the modes with strain energy density or maximum principal Green-Lagrange strain as the damage parameter is in a poor agreement with the experimental fatigue life within a factor of four. The model using effective stress as damage parameter can predict the fatigue life within a factor of two, which is the best prediction among the three models. It's concluded that the proposed model for fatigue life prediction with the effective stress can be used to estimate the fatigue life for a rubber mount of vehicle powertrain.