Coupling tomographic and thermographic measurements for in-situ thermo-mechanical tests

Abstract

In order to determine the thermo-mechanical properties of a complex 3D woven ceramic composite material, an experiment at high and inhomogeneous temperature and its dedicated full-field measurement procedure is developed. 3D tomographic images of the tested sample are captured at different stages of loading in a synchrotron beamline, and an infrared camera captures a side view of the sample as it rotates in the X-ray beam. A pin-hole projective model of the thermographic camera allows one to map the thermal field measured under numerous orientations onto a 3D mesh of the sample built from an initial tomographic image or a model. The projective model has to be calibrated, and an original procedure is proposed thanks to an integrated digital image correlation algorithm based on the "silhouette" of the sample (as only the protruding edges outlining the sample shape can be seen clearly). This procedure is illustrated with an experimental case study.

In situ tomographic study of a 3D-woven SiC/SiC composite part subjected to severe thermo-mechanical loads

“…A pin-hole projective model of the IR camera was calibrated and used to reproject the measured thermal fields onto a 3D mesh of the sample (Turpin et al, 2021). Fig.…”

Brightness and contrast corrections for stereocorrelation

“…The initial guess of extrinsic parameters is important since it allows a fair estimate of the intrinsic texture. In the case when the initial guess is too poor, convergence of the proposed algorithm becomes much slower, and a multiscale calibration approach [36] becomes necessary.…”

Identification of the effective interface between the homogenized phases of a dual-weave 3D composite

“…Then, IDVC can also be performed between those images, using a pyramidal scheme [30] that progressively transitions from blurred versions of the binary images into less blurred ones. This procedure results in the best set of parameters to describe the behavior of the sample borders.…”