Finite Element Simulation of Fatigue Damage Accumulation for Repaired Component by Cold Expansion Method

Abstract

This manuscript investigates the effectiveness of applying the cold expansion process to extend the fatigue life of mechanical structures. During the cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. This technique produces beneficial high compressive residual stresses which have been predicted by means of finite element models, both 3D for proper assessment of thickness effects. Finite element models have been developed to increase their complexity, Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The experimental results were compared to the damage calculated by the Miner’s rule and a new simple fatigue damage indicator based on an energy criterion. This comparison shows that the ‘energy criterion model’, which takes into account the loading history, yields a good estimation according to the experimental results.