Product Code: ICA12_403

Experimental and Numerical Analysis of Laser Beam Transmission in Continuous Fiber Thermoplastic Composites
Authors:
Mylène Deléglise, PRES Lille Nord de France, Mines Douai, DTPCIM; -
Benoît Cosson, PRES Lille Nord de France, Mines Douai, DTPCIM; -
Wolfgang Knapp, CLFA Fraunhofer ILT, c/o MINES ParisTech; Paris France
Presented at ICALEO 2012

Laser transmission welding has been demonstrated as being a suitable alternative to assemble continuous fiber thermoplastics composites. The knowledge and simulation of the mechanical properties obtained allow forecasting the mechanical strength of the final assembly. However, to estimate the required laser power and beam characteristics it is necessary to characterize the transmitted beam path and predict the intensity profile in the welding area. The presence of continuous fibers at a high fiber volume fraction disturbs the laser beam propagation. Process optimization requires understanding of the physics involved during laser beam propagation through continuous fiber composite media. Using ray tracing technique laser beam diffusion and absorption at the weld interface is modeled. The knowledge of the real fiber distribution in the material using composite material characterization allows combining modeling of optical beam path with material properties resulting from fiber architecture. The limits of the laser welding process become predictable independently from usual trial-and-error experiments. This approach can be extended to any other laser welding application on semi-transparent and non-homogeneous thermoplastic structures.