Laser transmission welding of composites-Part A: Thermo-physical and optical characterization of materials

In the present study, thermophysical and optical characterization of UD thermoplastic composites materials have been investigated. Knowledge of these parameters is of utmost importance to better understanding of any process that involves laser processing of materials. These properties play an important role during the simulation of the welding process. Two optical parameters namely transmission factor (Tλ) and reflection factor (Rλ) are measured using IRFT spectrometer and integrating sphere at the laser wavelength. The transmittivity coefficient (τλ) and reflectivity coefficient (ρλ) were determined using two approaches. A simplified experimental approach and numerical approach based on an inverse method program. Comparison between the two approaches is presented. A well-design device has been also developed in order to evaluate anisotropic thermal conductivities of composites. And finally we compared the experimental results to the analytical method concerning modeling thermal conductivities in composites.