Fatigue crack assessment of a rubber isolator in road engineering using the effective tensile stress criterion

Abstract

In this study, a newly developed fatigue criterion, effective tensile stress, was applied, for the first time, to a road-engineering isolator. This criterion reliably predicts crack initiation under both positive and negative R ratios without the need for curve-fitting procedures. By introducing a damaged-element removal program, the criterion was extended to include crack propagation, yielding a unified crack assessment framework. To focus on both crack initiation and propagation, an engine isolator, the Drum Mount, was used to validate this approach. The evaluation of both prediction and observation confirmed its effectiveness. The predicted fatigue crack initiation occurred at 2.76 million cycles, whereas the fatigue test was halted at 2.63 million cycles after a crack appeared. The predicted crack length was 13.8 mm, and the actual length after the test was 13 mm. The method could evaluate fatigue crack initiation and propagation under multiaxial conditions without artificial pre-cuts at different R ratios, offering an alternative approach to fracture mechanics for crack growth assessment. Therefore, this methodology could be helpful in anti-vibration design and failure analysis. Additional validation with more engineering cases is still necessary.