Consolidation during laser assisted fiber placement: Heating, compaction and cooling phases

Thermoplastic composites (TPCs) are emerging in the aerospace industry owing to their advantages over thermoset counterparts such as infinite shelf life, high fracture toughness, chemical and solvent resistance, and recyclability. Also, they are suitable for fast, automated manufacturing since chemical reactions are not required to obtain the final mechanical properties and shape of the TPC structures. Laser-assisted fiber placement (LAFP) has become a promising manufacturing solution with a potential in reducing the material scrap rates and labor time per component, and increasing the repeatibility. Moreover, thanks to the re-melting capability of TPCs, in-situ consolidated (without a post-consolidation step in an oven, press or autoclave) structures can be produced using the LAFP process, which can reduce the capital and energy costs associated with post-consolidation. For the aerospace industry to widely accept and use LAFP with in-situ consolidation, sufficient part quality with a feasible processing speed must be achieved. One of the primary quality indicators is the consolidation quality, which can be quantified by the remaining voids within the composite laminate after manufacturing. Proper consolidation quality can only be obtained once the underlying mechanisms and the relation with the process parameters are understood. The main goal of this thesis is therefore to improve the understanding on the consolidation process during LAFP with in-situ consolidation...