Functional integration of piezoresistive foams and dismantling systems for health monitoring and maintenance of modular composite structures

Aerospace structures serve both load bearing and protective roles, engineered to be lightweight without sacrificing structural performance. In addition to their traditional design requirements, modern engineering structures must address challenges and cross manufacturing, operational maintenance, or efficient thermal or energy management. These challenges must be reflected in the initial design phase and constitute the need to dismantle complex structures at the end of their life or rapid in-service repair them quickly during their operational life, especially for large and integrated composite structures. Sandwich structures are already widely used in aerostructures. Recent developments of piezoresistive foams and bio-based materials enable functionalization the skins and/or the core of these structures, adding additional smart functions such as structural health monitoring [1][2][3][4]. To repair or replace aerospace structures in a frugal and agile way, it is thought to have them coexist with a controlled on-demand dismantling system by anticipating the use of economical and non-polluting reversible assembly solutions from the design phase. The proposed thesis is in the field of research of advanced functional materials and structures. It focuses on studying the dynamic, transient and vibratory behaviour of sandwich structures using piezoresistive foams for material health monitoring, and an original disassembly system to handle sustainability requirements and foster innovation. A typical use case involves a flexible helicopter rotor blade subjected to gusts, local heating, or small particle impacts, or directed impacts (bird, hail). The objective of this thesis is to study the functional integration of piezoresistive foams and on demand debonding solutions into multifunctional composite sandwich structures, by analysing their transient and vibratory dynamic behaviour. The work will aim to understand the couplings between mechanical response, electrical response, damping and damage, to develop methodologies capable of describing and predicting the behaviour of these complex structures under representative loads. The thesis will rely on an approach combining experimentation and multiphysics modelling. Instrumented sandwich structures will be designed, fabricated and tested to assess their ability to detect damage events and monitor the evolution of their health over time, and to be dismantled if desired. The results will contribute to the development of innovative solutions for lighter, smarter, sustainable aircraft structures that are compatible with more efficient maintenance and repairability strategies. École doctorale : MEGEP - Mécanique, Energétique, Génie civil, Procédés Direction : Christine ESPINOSA Financement : MSCA COFUND BEST