Determination of Forming Speed at a Laser Shock Stretch Drawing Process

Abstract

Laser shock forming is a new high speed forming process based on TEA-CO2-laser induced shock waves. In former publications laser shock forming was already presented as a process which can be used for deep drawing, stretch drawing and cutting of thin copper and aluminum sheets. The process utilizes an initiated plasma shock wave on the target surface, which leads to the sheets forming. Several pulses can be applied at one point in order to achieve a high forming degree without increasing the energy density beyond the ablation limit. During the process, pressure peaks in the range of some MPa can be achieved. In order to classify the process in the framework of high speed forming processes, the temporal varying deformation velocity due to different materials have been identified based on a stretch drawing process by using different pulse energies. Therefore a new high speed measurement system based on the shadowing effects is designed and its suitability is shown. The determined strain rate of 520 s-1 meets one of the criteria for the classification of laser shock stretch drawing as a high-speed forming process.