Monitoring the plastic deformation progression of a specimen undergoing tensile deformation by moiré interferometry

Abstract

By using moiré interferometry we followed the deformation progression of an aluminium sheet metal sample subjected to a tensile test. At different load stages during the heterogeneous plastic deformation, we evaluated the strain fields from fringe patterns generated by using an interferometer with sensitivity vector perpendicular to the pulling direction. By analysing these strain fields, we determined the area where the process of strain localization began and the diffuse necking was formed. We observed that the localization started within the relatively large zone where the strains presented the fastest rate of change during the heterogeneous plastic deformation. In addition, by using a Monte Carlo-based technique, we carried out an uncertainty analysis of the performed strain measurements. We found that at each load stage, the relative standard uncertainties were constant and equal to 1.2%.