Hoop strain measurement during a SiC/SiC ceramic composite tube burst test by X-ray computed tomography

Silicon carbide-fibre/silicon carbide matrix (SiC/SiC) composites are candidate materials for accident tolerant fuel cladding in light water and advanced gas cooled nuclear fission reactors.  The mechanical and damage behaviour of ceramic composites is sensitive to the composite geometry, the microstructure and the loading state.

Reliable test methods are needed to investigate the subcritical damage that affects hermetic properties and strength, and this requires precise measurements under loading states that are representative of operating conditions.  A burst test of a SiC/SiC ceramic composite tube, pressurized by radial expansion was observed in situ by high resolution (synchrotron) X-ray tomography by James Marrow, Yang Chen, Luis Saucedo-Mora and Shixiang Zhao from Oxford, with Thomas Connolley from the Diamond Light Source.

The full field three-dimensional displacements were measured by digital volume correlation to obtain the relative radial and circumferential displacements of the tube wall for the first time.  This found non-uniform hoop strains that caused the distribution of subcritical cracking, which could influence the hermetic properties and strength.

Read the full paper in Experimental Mechanics.