A Fatigue Life Prediction Method of Rubber Material for Automobile Vibration Isolator under Road Load Spectrum

Automobile rubber isolator was subjected to random load cycle for a long time in the service process, and its main rubber material for vibration isolation was prone to fatigue failure. Since the traditional Miner damage theory overlooked the load randomness, it had a prediction error problem. In order to improve the prediction accuracy of rubber fatigue life, the traditional Miner damage theory was modified by random uncertainty theory to predict the rubber fatigue life under random load. Firstly, the rubber dumbbell-shaped test column, which was vulcanized from rubber materials commonly used in vibration isolators, was taken as the research object. The uniaxial fatigue test of rubber under different strain amplitudes and strain mean values was carried out. Then the fatigue characteristic curve of rubber with equivalent strain amplitude as the damage parameter was established. Secondly, the load spectrum of the rubber mount of an automobile powertrain was collected from different road conditions in a test field. Then the probability distribution of equivalent strain amplitude was deduced by using rain flow counting and mathematical statistics. Finally, according to the rubber fatigue characteristic curve and the probability density function of equivalent strain amplitude, the modified Miner damage theory was adopted to calculate the fatigue life of rubber under the collected road load spectrum. Based on the measured fatigue life of rubber, the prediction effects of the two damage theories were compared. The results showed that the prediction error was reduced by 30.89% compared with the traditional Miner damage theory.