Residual fatigue life analysis and comparison of an aluminum lithium alloy structural repair for aviation applications

A method for residual-fatigue-life estimation of repaired aluminium-lithium alloy structures designed for use in aerospace applications is presented. Crack propagation was investigated using the Abaqus software package while the stress intensity factor was calculated using the FRANC3D package. Paris equation was applied to estimate the fatigue-crack growth rate. The residual fatigue life of and corresponding a-N curve for the repaired structure were obtained via post-processing under varying conditions of repair-structure shape, size, position, and stress levels. Results demonstrate that structural repairs possessing relative width, height, and thickness values of 35.7%, 50%, and 83.3%, respectively, tend to increase the residual fatigue life of the overall structure.