COMPUTERIZED SIMULATION OF LASER-BEAM WELDING, MODELING AND VERIFICATION

The theoretical basis for the numerical simulation of stationary penet ration welding with a laser beam is presented. The characteristics of the self-consistent model are the following. Vapour channel, weld pool and solid are considered as a nonlinear thermodynamic continuum. The laser-induced channel formation, multiple reflection of the laser beam in the channel, and plasma generation are taken into account. The abs orption coefficient of the plasma is assumed as dependent on the degre e of ionization. The geometry of the channel is determined on the basi s of the pressure equilibrium at the channel surface taking the enthal py of the molten mass into account. The input parameters for the simul ation are the geometry of the workpiece, the material characteristic v alues dependent on temperature and the technological parameters such a s laser beam power, beam diameter at focus, focus position, divergence angle of the beam, type of working gas and welding velocity. The resu lts comprise the distribution of enthalpy and temperature, the shape a nd dimensions of the vapour channel of the weld pool and of the comple ted weld, and the energy losses by reflection, vaporization, thermal r adiation and plasma shielding. The model was verified with welding exp eriments on steel and aluminium alloy. Data taken from the literature were also used for verification.