An energy method for predicting fatigue life, crack orientation, and crack growth under multiaxial loading conditions

A method based on a virtual strain-energy (VSE) concept has been shown to be effective for use in predicting multiaxial fatigue lives of two widely-used commercial alloys subjected to in-phase and out-of-phase biaxial loading conditions . This paper is intended to reaffirm the effectiveness of the VSE method for predicting fatigue life and to demonstrate its inherent ability of describing fatigue behavior such as crack orientations and crack growth characteristics. To this end, the basic concept of the method is briefly reintroduced and validated with fatigue data obtained from two different heats, a domestic and a foreign origin, of type 316 stainless steel subjected to cyclic torsion with static axial loading in tension or compression. Excellent agreement in general was observed between predictions and experimental results except in a case of cyclic torsion with a static compression, which appeared to show beneficial to torsional fatigue life.