Measurement of the average strain rate of thin aluminum deformation under laser shock

Abstract

A novel optoelectronic measurement system using a beamshading technique is developed to detect the dynamic characteristics of a metal sheet under laser shock in laser shock forming (LSF), including deformation, strain, and strain rate. Experiments conducted yield the dynamic deformations at two points on an aluminum sheet with a thickness of 0.25 mm in LSF. The average strain rates calculated in the experiments are 5.46 × 10 2 , 4.71 × 10 2 , and 3.59 × 10 2 s −1 when the targets were hit by laser pulses with energies of 5, 6, and 8 J, respectively. The results show that the strain rate induced by laser shocking is not at the ultrahigh level of 10 6 -10 7 s −1 as generally estimated in past studies, which offers an experimental reference for the deformation study of strainrate-dependent metal materials in LSF.