Développement de méthodes de réparation des composites à matrice thermoplastique utilisant le soudage par induction

Abstract

The use of high performance thermoplastic composite materials is ever more present in today’s industry. These materials are expensive and on occasion of structural damage, common practice often dictates the replacement of the whole piece. The development of an effective and appropriate repair method aiming at partially or completely recovering the mechanical performance of the structure has therefore become a necessity. This experimental work focuses on the recovery of tensile properties of samples repaired by patches. Patches are welded to samples using the induction welding process. Firstly, plates of polyphenylene sulfide reinforced with unidirectional carbon fibres (CF/PPS) are moulded and tested in tension in order to define the tensile mechanical properties. The samples are then drilled in their center, damaging them. Finally, damaged samples are repaired using welded patches on the sample surface. The repair and sample materials are identical. An induction weld using a heating element - stainless steel mesh with PPS matrix - is performed at the interface between the sample and patch. A comparison between the tensile mechanical properties of undamaged and repaired samples is proposed. The recovery of these properties is quantified, allowing a characterization of the repairs usefulness in tension load. Various patch thicknesses and ply stacking sequences are used and the effects of the patches overlap length on the tensile mechanical properties of samples are investigated. One and twosided repairs are made. Observations on the effects of adding a plug to replace the missing material in damaged samples are made. This mainly proves that an increasing number of plies in a patch boosts tensile strength recovery. A threshold was found. Observations on quasi-isotropic repairs show that tensile strength also improves as the length of the patch increases up to a certain size. This is enhanced with the patch's thickness. This research is a preliminary work in the development of high performance thermoplastic composite repairs.

Date	27 Aug 2015
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Martine Dubé (Supervisor)