Investigation on formability improvement in laser shock hydroforming

摘要

Laser shock hydroforming is a novel microforming method that adopts laser energy as the driving force and liquid as the medium to transmit pressure. The method combines the advantages of laser shock forming and micro hydroforming. Previous research has demonstrated that this method can deform thin sheets into complex shapes at high strain rates. We know that the formability of materials is improved at high strain rates, but experimental analysis on this method alone cannot examine the deformation process. Therefore, this study first conducted free- and die-forming experiments of laser shock hydroforming to characterise the features of the deformation process and understand the factors that may contribute formability enhancement. Experimental results were discussed to uncover the formability of thin sheets under different conditions, including the laser energy and the effect of the die. Then, a numerical model was established considering fluid-solid interaction. The deformation process, sheet velocity, contact stress and strain rate were investigated through numerical means, and these indicators explain the mechanism of formability improvement in this method. Furthermore, the numerical results indicate a positive phenomenon-pressure equalisation-which might be due to the reflection of pressure off the rigid side wall of the liquid chamber.