Thesis topic of SABBAGH Khaireddine : Crack propagation under variable amplitude cyclic loading in bio-sourced composite structures.

Abstract : This thesis aims, in a first step, to consolidate our approach in damage tolerance on composite materials. Secondly, this approach will be supported by a probabilistic approach in reliability of the various variables of the mechanics of the rupture or the implementation (rate of energy restitution, speeds and thresholds of propagation, manufacturing process).
The study will be carried out on composite materials (unidirectional or woven linen fibers/thermoset resin). It will be essential to take into account in the scientific approach environmental conditions (temperature, humidity) and loading conditions (various loading ratios R).
The manufacturing of the composite parts as well as the tests will be carried out at Isae-Supméca within the Quartz laboratory. The RTM (Resin Transfer Molding) process is targeted for the implementation of composites. The bench developed in the laboratory dedicated to fatigue testing will be used to study damage tolerance.
Development of a damage evolution model to stochastically propagate the identified damage mechanisms. Then, a combination of the different types of damage will be used to calculate the temporal evolution through reliability analyses of the composite structures. The probabilistic model must take into account the stochastic evolution of the damage accumulated in service, the inspection of such damage, the residual degradation of the damaged structure. The reliability of a damage tolerant composite structure can be evaluated on a quantitative basis allowing engineers to establish a maintenance plan and to estimate inspection intervals.

Supervison :

under the supervision Prof Imad TAWFIQ (ISAE-Supméca), Prof Chokri BOURAOUI (Université de Sousse) and MCF- HDR Olga KLINKOVA (ISAE-Supméca)