Fatigue life estimation of a non-linear system due to random vibration

Random response analysis is a linear approach, while most real life random vibrations involve nonlinear components. It is challenge to analyze a nonlinear system subjected to random vibration. This paper presents an Abaqus FEA approach on the fatigue life calculation of an automobile assembly with rubber isolators subjected to random vibration. Random loading is categorized using Power Spectral Density (PSD). An equivalent dynamic analysis or a random response analysis was used to obtain the maximum stress level and location from random vibration. A MATLAB routine was used to post process Abaqus PSD response to calculate the stress cycles/peaks and the fatigue damages were estimated. Hyperelastic behavior of the rubber isolator was derived from Abaqus materials module and the corresponding tests. Random vibration test results with the same PSD input were used to tune and verify the FEA model.