Low-cycle fatigue life prediction under multiaxial non-proportional loads

According to the critical plane principle, a new multiaxial fatigue damage parameter is proposed based upon the varying behaviour of the energy on the critical plane, where the non-proportional scale representing the grade of additional hardening is introduced as a friction coefficient. By the linear damage accumulative rule, the relationship between the maximum damage and the fatigue cycles is derived and a new approach of predicting the multiaxial non-proportional low cycle fatigue life is achieved. The experimental results of fatigue tests indicate a good agreement with the presented predictions.