Fatigue life prediction for 7050-T7451 aluminum alloy plate with scratch defect

Abstract

Fatigue damage of 7050-T7451 aluminum alloy plate with scratch was studied,and the fatigue life of aluminum alloy plate after scratching was predicted considering the common effects of the residual stress,plastic damage and fatigue load. The nonlinear dynamic finite element( FE) analysis was conducted to simulate scratch generation,and the residual stress field and plastic strain field near scratch were obtained.According to the equation of plastic damage,the initial damage field near scratch caused by plastic deformation in the scratching process was calculated. Based on the multiaxial fatigue damage model,the finite element numerical method was established to analyze fatigue damage,and the calibration of material parameters in the damage evolution equation was conducted. This method was used to predict the fatigue life of scratched aluminum alloy plates with synthetically considering the residual stress field,the initial plastic damage and fatigue damage. The predicted results were compared with results from the fatigue test of specimens,and the theoretical prediction was in accordance with the test results of fatigue life. A new method and a practical means for fatigue life prediction of metal component with scratch defect were provided.