Thermal modeling in composite transmission laser welding process: light scattering and absorption phenomena coupling

In previous studies [1, 2], we have presented a detailed formulation of a macroscopic analytical model of the optical propagation of laser beams in the case of unidirectional thermoplastic composites materials. This analytical model presented a first step which concerns the estimation of the laser beam intensity at the welding interface. It describes the laser light path in scattering semi-transparent composites (first component) by introducing light scattering ratio (D) and scattering standard deviation (sigma). The absorption was assumed to be negligible in regard to the scattering effect. In this current paper, in order to describe completely the laser welding process in composite materials, we introduce the absorption phenomenon in the model, in the absorbing material (second component), in order to determine the radiative heat source generated at the welding interface. Finally, we will be able to perform a three dimensional temperature field calculation using commercial FEM software. In laser welding process, the temperature distribution inside the irradiated materials is essential in order to optimize the process. Experimental measurements will be performed in order to confirm the analytical model.