Solution of inverse heat conduction problem for determining heat input, weld shape, and grain structure during laser welding

The technique of solving the inverse heat conduction problem to determine the steady state welding conditions corresponding to observable or desired weld features is outlined. The objective function includes calculated and experimental value's of the temperature related functions, constraints, and regularisation of unknown parameters. The algorithm used to determine the minimum of the objective function is presented. As an example, the temperature field and its corresponding grain structure have been calculated taking into consideration the latent heat and fluid flow in the laser welding of two aluminium alloys. The weld width and texture orientation haw been used as the temperature related functions. The results of the simulations are directly compared with the experimental evidence.