Experimental and numerical investigation of laser-welding of long fiber thermoplastic composite

As a result of their advantages, i.e. recyclability, weldability, environmental compatibility, long fiber thermoplastic composites (LFTPC) are increasingly used in many industrial sectors (automotive, aeronautic, medical devices). Several joining techniques have been developed (induction welding, resistance welding, adhesive bonding, and laser welding). The laser welding process offers advantages such as excellent aesthetic appearance, process flexibility allowing complex geometries, no use of chemical glues. After developing the technical basics of the laser based joining process of LFTPCs the current paper presents advanced mechanical characterization of laser welded components. A test procedure for a multi-axial mechanical characterization of the laser welded seam on the basis of the ARCANMINES device is proposed. This devise is also used in the analysis of the mechanical behavior of adhesive bonding and allows a direct comparison of the different assembly techniques . The microscopic analysis shows the presence of fibers in welded zone. The mechanical behavior of the laser welded seam can entirely be determined by a transversely isotropic stiffness matrix. A numerical model allows simulation of the lap shear test in two configurations: weld seam in fibres' direction and orthogonal to the fibres. The numerical simulations are confirmed by the experimental data. This allows direct forecast of the weld seam geometry for desired mechanical behavior of laser welded structural components made of LFTPC.