On 12th June 2019, Marion Broutelle defended her thesis. Awarded by ISAE-SUPAERO, her work was supervised by ICA (Institut Clément Ader), the MEGeP (Mécanique, Energétique, Génie civil & Procédés ) Doctoral School, and IRT Saint Exupéry. The high quality and the relevance of Marion’s thesis contributed to get significant results as a part of CMC OxVL project.

THESIS SUBJECT

“Étude des mécanismes d’endommagement d’une liaison boulonnée de matériaux composites à matrice céramique oxyde/oxyde”

About her thesis

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.

CMC OxVL Project

Development of processes to synthetize oxide based materials (oxide fibers and oxide matrix ) offering an alternative with a high durability to Titan based alloys and Nickel based alloys, in the temperature range of 500°C to 800°C, for civil aircraft applications.

Jury

Nathalie GODIN	Rapporter	Lecturer (HdR) / INSA Lyon
Frédéric LAURIN	Rapporter	Engineer (HdR) / ONERA
Christian HOCHARD	Examiner	Professor / LMA Marseille, Aix-Marseille Université
Alain DAIDIE	Examiner	Professor/  INSA Toulouse
Florent BOUILLON	Invited	Engineer / Safran Ceramics
Frédéric LACHAUD	Thesis Director	Professor / ISAE-SUPAERO
Ludovic BARRIERE	Thesis co-Director	Engineer / IRT Saint Exupéry

PUBLICATIONS

• Comportement en matage de composites à matrice céramique oxyde/oxyde – M. Broutelle, F. Lachaud, C. Dupleix-Couderc and A. Daidié  – SF2M (Société française métallurgie et matériaux), Albi, France – 2016
• Comportement en matage de composites à matrice céramique oxyde/oxyde – M. Broutelle, F. Lachaud, C. Dupleix-Couderc and A. Daidié – JNC 20 (20es Journées Nationales sur les composites), Champs sur Marne, France – 2017
• Mechanical behavior of oxide/oxide ceramic matrix composite bolted joints – M. Broutelle, F. Lachaud, A. Daidié, L. Barriere and F. Bouillon – ECCM 18 (18th European Conference on Composite Materials), Athens, Greece – 2018