Abstract
An electronic speckle pattern interferometry (ESPI) system, which makes it possible to observe dynamic phenomena, was applied to investigate the plastic deformation process in tensile experiments of aluminum alloy samples. The dynamic behavior of a strain-localized band which propagated through a specimen was thoroughly investigated. A pulsating fringe variation of the order of 1 Hz was discovered to be the fine structure of the propagating band. Fringe pulsation is caused by localized strain pulsation which suggests that the stress relaxation process propagates periodically with a time constant which governs the dissipative characteristics of a heterogeneous material.