A Modified Multiaxial Fatigue Damage Criterion Incorporating Mean Stress and Stress Biaxiality Effects in High‐Cycle Fatigue

The effects of mean stress and stress biaxiality under complex loading conditions pose significant challenges in engineering design, and few studies bridge the multiaxial and stress ratio effects in a unified framework. This work addresses these gaps by proposing a fatigue damage model that synergistically integrates the variations in multiaxial stress and stress ratio. The model leverages critical plane concepts to capture failure mechanisms while incorporating stress ratio dependencies through physically informed parameters. Experimental validation using two steels (AISI 4340 and BG801) demonstrates the model's capability to predict both fatigue life and crack initiation planes under multiaxial and variable stress ratio conditions. Furthermore, the approach provides insights into material behavior transitions under varying stress states, offering a practical tool for engineering applications that require the simultaneous consideration of complex loading scenarios.