Multiscale monitoring of localized plastic strain evolution stages in notched aluminum AA 2024 alloy tension specimens by acoustic emission and television-optical techniques

Localized plastic strain evolution stages in notched aluminum AA 2024 alloy tension specimens have been investigated. Integral calculations of the microscale strain have employed acoustic emission data. The mesoscale strain has been studied by calculating the normalized integral equivalent shear strain from television-optical data. To gain insight into the special features of the macroscale strain, the time derivative of the applied loading has been examined. Early in the loading process, acoustic emission is shown to respond best to deformation and fracture. This makes it possible to reveal a transition from stage I to stage II in the evolution of localized strain where the mesoscale level comes to dominate over the macroscale one. At high strains, the digital image correlation method provides a consistent characterization of the predominance of the mesoscale level. The results of the investigations under review point to the fact that an analysis of localized plastic strain stages is an effective means of interpreting the data on the evolution of plastic flow at different scale levels.