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PhD Thesis Defense M. Broutelle – Composite materials with ceramic oxide/oxide matrix

Event information

Start date :12/06/2019

End date :12/06/2019

Time :10:00

Location : salle Clément Ader - ICA, 3 rue Caroline Aigle, 31400, Toulouse

PhD Thesis Title: « Étude des mécanismes d’endommagement d’une liaison boulonnée de matériaux composites à matrice céramique oxyde/oxyde »
By Marion Broutelle

Doctoral School: École Doctorale Mécanique, Energétique, Génie civil & Procédés – MEGeP (ED 468)

Thesis of ISAE-SUPAERO, prepared at ICA (Institut Clément Ader) and IRT Saint Exupéry.

Summary

The purpose of this thesis is to analyse the mechanical behavior of bolted joints made of oxide-based CMC (Ceramic Matrix Composites). It is part of a project aiming at developping and characterizing CMC with a new process less expensive than the former ones. These composites are good candidates to be introduced in aircraft engines. The studied material is composed of alumina fibers (Nextel™610) and an alumina matrix.

This study is based on experimental observations and numerical simulations. The experimental part focuses on the bearing failure mode as it is the prefered mode of Failure for bolted joints. Standard bearing tests are carried out to obtain a first damage chronology. Then, a new test setting is proposed in order to allow a direct observation of the damage development on the bearing plane. Some interfering damage can be reduced with this setting, as it avoids some additional operations as the disassembly or the cutting of the standard test pieces. Thanks to the new experimental observations, the damage chronology is refined. Finally, trials are conducted on single-shear bolted joints. First, the influence of several factors is highlighted through an exeperimental design campain. Then, two reference configurations are studied by analysing the data obtained with digital image correlation and acoustic emission monitoring.

Damage constitutive laws are implemented in Abaqus to simulate the material progressive degradation. To do so, characterization trials are conducted to identify the necessary mechanical parameters. The different tests performed are simulated and compared to the experimental results in order to measure the model relevance. Propositions are made to improve its accuracy.