Multiaxial Fatigue Damage Accumulation under Variable Amplitude Loading Conditions

Generally, structures and mechanical components are subjected to multiaxial loadings under random conditions. However, fatigue damage accumulation under such loading conditions remains a hard topic to deal with. This subject is an ultimate challenge in fatigue characterization and it contains all topics within the multiaxial fatigue subject, ranging from cyclic plasticity to sequential loading effects. In this work two fatigue damage accumulation rules and the Stress Scale Factor (SSF) equivalent shear stress as damage parameter, are used to evaluate the accumulated damage from multiaxial random loadings where the loading paths and sequences results were obtained from the literature. Results show that there exists a conceptual problem in the decision trigger of the selected damage accumulation rules. Some solutions are pointed out to overcome this drawback.