Démantèlement de composites stratifiés par choc laser pour des applications de réutilisation

Carbon fibre reinforced polymers (CFRPs) are widely used in aerospace, wind energy, and sports applications due to their excellent specific mechanical properties and the reduction in emissions made possible by lightweight structures. However, a significant amount of composite waste is generated each year, coming from production or end-of-life structures, raising major challenges in terms of recycling and sustainability. Recycling and reusing continuous-fibre composites represent promising solutions to reduce the carbon footprint. Nevertheless, conventional methods, whether mechanical, chemical, or thermal, often lead to fibre degradation, the production of pollutants, or insufficient quality of the recovered materials.This thesis proposes a novel process based on laser shock dismantling at the ply scale. High-energy nanosecond laser pulses generate shock waves at the surface of the material, inducing localized delamination. Unlike traditional approaches that aim to separate individual constituents, this technique allows the recovery of entire plies or groups of plies while preserving fibre length, a key advantage for high-performance reuse. The recovered materials can be directly reused in less demanding applications or indirectly through reassembly of the dismantled plies via structural bonding.Additionally, this work investigates the effect of ageing on composites. Oxidation layers on the resin and composite are characterized, and the influence of ageing on laser parameters is analyzed to allow selective removal of oxidized plies. Moreover, a guided-wave monitoring method (SHM) is developed with a dual purpose: detecting structural changes due to ageing, enabling early assessment of natural degradation, and controlling the dismantling in real time by detecting delamination events and quantifying the affected areas.This multidisciplinary work demonstrates that laser shock dismantling, combined with the study of ageing and in situ SHM monitoring, provides an effective pathway for the recovery and reuse of composite materials while minimizing their environmental impact.