Multi-Axial Fatigue-Life Prediction via a Strain-Energy Method

摘要

A strain-energy-based method has been developed to predict the fatigue life of a structure subjected to either shear or biaxial bending loads at various stress ratios. The framework for this method is an advancement of previously conducted research that validates a uniaxial energy-based fatigue-life-prediction approach. The understanding behind the approach states that the total strain energy dissipated during a monotonic fracture and a cyclic process is the same material property, where the experimental strain-energy density of each can be determined by measuring the area underneath the monotonic true stress-strain curve and the area within a hysteresis loop, respectively. The developed framework consists of two elements: a life-prediction method that calculates shear fatigue-life cycles and a multi-axial life-prediction method capable of calculating biaxial fatigue-life cycles. A comparison was made between the two framework elements and experimental results from three different aluminum alloys. The comparison shows encouraging agreement, thus providing credence in the prediction capabilities of the proposed energy-based framework.