A Method for Predicting Fatigue Life of Rubber Isolators at Power Spectral Density Load

Rubber isolators are widely used under random vibrations. In order to predict their fatigue life, a study on the fatigue analysis methodology for rubber isolators is carried out in this paper. Firstly, taking a mount used for isolating air conditioning compressor vibrations as studying example, accelerations versus time of rubber isolator at both sides are acquired for a car under different running conditions. The acceleration in time domain is transformed to frequency domain using the Fourier transform, and the acceleration power spectral density (PSD) is the obtained. Using the PSD as input, fatigue test is carried for the rubber isolator in different temperature and constant humidity conditions. A finite element model of the rubber isolator using ABAQUS is established for estimating fatigue life, and model validity is verified through static characteristic testing. Dynamic responses of the rubber isolator at frequency domain are calculated if a unit load is applied. The estimated dynamic responses are then imported into Fe-safe for calculating fatigue analysis of the rubber isolator. The proposed methods in this paper are validated by comparing the calculated with the measured fatigue life. To enhance the fatigue life of the rubber isolator, structural optimization is carried out by optimizing main spring parameters. Fatigue life calculation of the optimized rubber isolator is then carried out and it is shown that the isolator meets design requirements. A frequency-domain calculation method of fatigue life proposed in this study can be used for assessing the fatigue life of rubber isolators under random vibration.