Multiaxial fatigue life prediction method based on path-dependent cycle counting under tension/torsion random loading

A path-dependent cycle counting method is proposed by applying the distance formula between two points on the tension-shear equivalent strain plane for the identified half-cycles first. The Shang-Wang multiaxial fatigue damage model for an identified half-cycle and Miner's linear accumulation damage rule are used to calculate cumulative fatigue damage. Therefore, a multiaxial fatigue life prediction procedure is presented to predict conveniently fatigue life under a given tension and torsion random loading time history. The proposed method is evaluated by experimental data from tests on cylindrical thin-walled tubes specimens of En15R steel subjected to combined tension/torsion random loading, and the prediction results of the proposed method are compared with those of the Wang-Brown method. The results showed that both methods provided satisfactory prediction.