A thermal-elastic analysis on laser-induced reverse bulging and plugging in circular brass foil

A new failure mode is observed in circular brass foils induced by laser beam. The new failure is based on the following experimental facts: (1) the peripheries of the circular brass foils are fixed and the surfaces of the foils are radiated by laser beam; (2) the laser beam used is considered to be non-Gaussian spatially, actually an approximately uniform distribution limited in a certain size spot; (3) the pulse on time of laser beam should be 250 mu s, i.e. so called long duration pulse laser. The failure process consists of three stages; i.e. thermal bulging, localized shear deformation and perforation by plugging. The word 'reverse' in 'reverse bulging and plugging mode' means that bulging and plugging occur in the direction of incident laser beam. To study the newly-discovered type of failure quantitatively, analytical solutions for the axisymmetric temperature field and deflection curve are derived. The calculated results show that the newly discovered failure mode is attributed to the spatial structure effect of laser beam indeed. (C) 1998 Elsevier Science Ltd; All rights reserved.