LASER HEATING AND THERMAL STRESSES TIME EXPONENTIALLY HEATING PULSE CASE

Abstract

Model studies of laser heating process minimize the experimental time and cost and give insight into the laser workpiece interaction mechanism. In the present study laser pulse heating is modelled and the governing equation of heat transfer, including phase change process, and thermal stresses are solved numerically using a control volume approach. In order to account for the time variation of the laser heating pulse, time exponentially varying pulse intensity is employed in the analysis. Since the heating conditions are considered to be axisymmetric, two dimensional case is introduced in the analysis. The temperature and stress fields are simulated for steel. It is found that temperature level attains considerably high values in the melt zone and pulse parameter (β/γ) with small values (1/2) results in large evaporated zones. Equivalent stress level increases rapidly in the region close to the melt surface and two stress peaks are developed in the radial direction. The location of stress peaks remains same with progressing heating period; however, the magnitude of second peak reduces with advancing heating periods.