16 Juillet – Thesis defense - Léonard Turpin

09 h30 By videoconferencing

In-situ experimental study of damage for a ceramic matrix composite submitted to multi-axial loading.

SiC/SiC ceramic matrix composites are expected to replace super-alloys in aircraft engine hot area. Their 3D-woven structure is designed to match part geometry and loading. The meso-structure includes complex zones, for instance in bend or in junction. A good understanding of the thermo-mechanical behaviour of those zones is needed to model, to design and to certify aeronautical parts.
An in-situ thermo-mechanical experiment is set up, instrumented with x-ray tomography and infrared camera. It provides the behaviour of critical zones submitted to multi-axial loadings and, namely, the first occurrences of damage. To efficiently exploit the (huge) amount of data provided by full-field measurement, a procedure is set up to identify material properties. Tomographies are reconstructed
thanks to an algorithm which in-paints incomplete sinograms. They are namely used to build an image-based mesh of the sample. After pin-hole model calibration of the camera, the thermal field is re-projected into the mesh. The two measured fields (volume and surface temperature) are then put in a common referential relating to the part. Eventually, the kinematic measurement is made by integrated digital volume correlation coupling those two fields.
This procedure closely links material meso-structure to macroscopical behaviour.

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