STRUCTURE REPAIR BY ADDITIVE FRICTION STIR DEPOSITION: MECHANICAL RESPONSE OF THE REPAIRED INTERFACE

Two solid-state processes, cold spray and Additive Friction Stir Deposition, are compared with the aim of repairing damaged aerospace structures of reusable satellite launchers. The samples obtained by cold spray feature a material health prohibitive for repair. Conversely, samples repaired by AFSD show excellent microstructural continuity between the substrate and the deposited material. The impact of the process on the microstructure of the repaired part thus obtained is analyzed through fine characterization using scanning electron microscopy. The mechanical response of the repaired structure is analyzed using hardness mapping, as well as tensile tests carried out on specimens sampled at different heights in the deposited material. These results indicate a strong thermo-mechanical impact of the process, both on the substrate and on the deposited material. A revalidation methodology based on the analysis of local deformation gradients by Digital Image Correlation is also described in this paper.