Effect of Loading History of Aluminum on Fringe Pattern in Electronic Speckle Pattern Interferometry

Abstract

Deformation behaviors of aluminum sheet that experienced deformation were measured using electronic speckle pattern interferometry method. The specimens with notch were tensile loaded to various load levels and reloaded to the same level. In order to reveal loading history of material, the changes in two-dimensional displacement fields during the reloading were observed as interferometric fringe patterns. The deformation behavior observed in the tensile test generally consisted of the three different stages of macroscopically elastic deformation, local plastic deformation in a small region near the notch tip, and large scale plastic deformation with formation of plastic region around the notch. The transition process of these stages changed depending on the load level in which the specimen experienced in past. Consequently, the difference in the deformation behavior in the reloading was observed as the changes in fringe patterns. The deformation behavior in the reloading was analyzed with the observed fringe patterns.