Fatigue damage analysis of aluminum alloy by ESPI

Abstract

In this study, Electronic Speckle Pattern Interferometry (ESPI) and acoustic microscopy were applied to analysis of the fatigue of aluminum alloy. Effect of fatigue damage on the macroscopic deformation behavior during a tensile test has been analyzed with the interferometric fringes. Resultant fringe pattern showed that the elastic compliance in the damaged area increased as the fatigue cycle before the tensile test (Pre-fatigue cycle) increased, resulting in the occurrence of strain localization. In order to know the relation of between the deformation behavior and the microstructural change of the specimen, the acoustic property on the surface has been investigated by a scanning acoustic microscope. It was found that the surface acoustic velocity in the load direction in the pre-fatigue test increased with increasing the pre-fatigue cycle. The results have been discussed based on the fatigue stages of the change in residual stress, local plastic deformation, and the crack initiation.