Effect of thermo-oxidation on the behavior of adhesive joints for aeronautical applications

This thesis is based on the six month internship done at ISAE-ENSMA (École Nationale Supérieure de Mécanique et d'Aérotechnique; Poitiers, France) during "Erasmus +" . The internship has been done in the "Physics and Mechanics of Materials" department of the research institute Pprime and it has been realized thanks to the collaboration with SAFRAN Composites. The topic of the study originates from the the work of the PhD student Julie Masson concerning thermo-oxidative aging inside a Titanium/Epoxy/Titanium single lap joint. The subject of the experiments was a different type of adhesive: instead of a Ti/Epoxy/Ti assembly I studied a Ti/(Epoxy matrix + PA66)/Ti assembly. The main objective of the internship was to observe the evolution of the physical and mechanical properties of the adhesive inside the single lap joint due to thermo-oxidation. This study has been carried out with two main techniques: • Surface analysis Using a 3D image acquisition device to look at the state of the surface and assessing the shrinkage evolution, searching for debonding and crack formation/propagation. • Nanoindentation To evaluate the evolution of local properties of the material (Elastic Indentation Modulus EIT) with thermo-oxidation. The fist half on the internship concerned the study of the subject and the creation of a protocol for the measurements, the latter was about the analysis of the data acquired. The results obtained show that shrinkage and the EIT are affected by thermo-oxydation for both Epoxy and PA66 fibre materials and that the ageing rate is similar for the two materials.