An Energy-Based Method for Multi-Axial Fatigue Life Calculation

Abstract

An accelerated method for determining the material strength of Aluminum 6061-T6 has been developed for prediction of fully-reversed shear and biaxial fatigue life. The framework for this accelerated method is developed in accordance with a previously developed uniaxial energy-based prediction approach, which states: the total strain energy dissipated during a monotonic fracture and a cyclic process is the same material property, where each can be determined by measuring the area underneath the monotonic true stress-strain curve and the area within a hysteresis loop, respectively [1]. The developed framework consists of the following two elements: (1) The development of a life prediction and estimation implementation scheme for calculating effective shear fatigue life cycles, and (2) the development of a constitutive law for multi-axial fatigue life prediction based on analytical comparison with biaxial fatigue experimental data. A comparison between these two framework elements and experimental results for Al 6061-T6 has been conducted to show that there is good agreement, thus validating the prediction method and the developed procedures of the entire framework.