Probabilistic approach for predicting fatigue life improvement of cracked structure repaired by high interference fit bushing

Abstract

The purpose of this paper consists in developing a probabilistic approach for predicting fatigue life improvement of 7075-T6 cracked Single Edge Notch Tension (SENT) specimen repaired by high interference fit bushing. The developed approach is carried out by coupling FE-analysis and Monte Carlo reliability method. In this context, a 2D- finite element analysis of the cracked SENT specimen using ABAQUS commercial software is established to: (i) simulate the interference fit process and (ii) to predict the fatigue life improvement after repair. The non-linear isotropic/kinematic hardening model embedded in ABAQUS is used to characterize the material behavior. Different stress levels, different interference fit sizes and different expanded hole diameters are investigated. As a result, crack arrest hole diameter equals to 6 mm with larger interference fit size (IFS = 0.2 mm) provides higher beneficial compressive residual stress distribution and higher fatigue life improvement than drilling hole near the crack tip. The iso-probabilistic S-N curves and the Reliability-Life curves after repair can be determined for different interference fit sizes and different expanded hole diameters. This probabilistic approach can be used with the interference fit process as an interesting and practical tool to ensure an optimal maintenance planning for cracked structures and to improve the fatigue lives of these cracked components that cannot be replaced as soon as the cracks are observed, especially in the aeronautical filed.