Study on the Method to Predict the Fatigue Life of a Rubber Mount

Failure analysis and fatigue life prediction are important steps in the design procedure of industrial products to assure the safety and reliability of their components. Two methodologies to predict the fatigue life of a rubber mount based on the continuum damage mechanics are proposed, analyzed and compared in this study. The maximum principle strain and strain energy density release rate were select as the quantities to predict the crack nucleation life in these two methods, respectively. The natural rubber material material’s fatigue life equation (ɛ-N) was acquired based on uniaxial tensile test and fatigue life tests of the natural rubber in the first method. A damage variable was introduced and the evolution function of cumulative damage in the rubber material was derived in the second method. The parameters in the damage function were also acquired based on uniaxial tensile tests and fatigue life tests of the natural rubber specimens. Then the strain distribution contours and the maximum principal strains of the rubber mount at different loads in the x and y directions were obtained using a finite element analysis (FEA) method. The maximum principal strain was used as the fatigue parameter, which was substituted into the natural rubber’s fatigue life equation and the damage function, to predict the fatigue lives of the rubber mount. Finally, the fatigue lives of the rubber mount under various loads were measured on a fatigue test rig to validate the accuracies of the fatigue life prediction methods. The test results indicated that the fatigue lives predicted agreed well with the test results and the fatigue prediction method should be applicable to both rubber and other types of components.