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

A novel optoelectronic measurement system using a beam-shading 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 x 10(2), 4.71 x 10(2), and 3.59 x 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 strain-rate- dependent metal materials in LSF. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)