Analyse et comportement de renforcements de structures mécaniques par des patchs composites.

Abstract

The reinforcement of damaged structures, by bonding composite patches, is a promising and beneficial repair technique, especially in the field of air transport. This method consists in reinforcing preventively damaged structures, in order to delay the initiation of cracks or to stop their propagation. It requires a good understanding of the stress states and the behavior of the structures involved. For the analysis of normal and shear stresses in the patch-glue-structure assembly, Our contribution is composed of two parts. The first part is based on a two-dimensional numerical study using the finite difference method for solving the equilibrium equations and analytical models obtained from the literature. The configuration is a double overlap of an aluminum plate subjected to different types of solicitations. Taking into account the two-dimensional effects and the difference of the Poisson’s ratio allowed us to determine the stress distribution especially in the adhesive layer representing the weakest link. Subsequently, an optimization by the Genetic Algorithm method was considered to determine the optimal fiber orientation for a better design. The second part is represented by two single and double overlap configurations of an Aluminum plate cracked on one side and loaded in tension. Under such conditions, a numerical finite element study in ANSYS 2020 R2 was considered. The stress distribution in the patch, the adhesive, as well as the reduction rate of the stress intensity factor in mode I were determined. The cohesive zone model (CZM) method was introduced using the bilinear delamination interface method (BID) for the study of the decohesion of the patch-glue and structure-glue contact interfaces for different fiber orientations of the composite patch.