In-situ imaging of advanced materials subjected to in-plane biaxial loading using X-ray micro-computed tomography

This study presents development of a novel in-situ biaxial test that enables microscale observation of deformation and failure in advanced aerospace materials using synchrotron-based X-ray micro-computed tomography (μCT). As a proof of concept, the biaxial test is used to study deformation of a Ripstop Nylon fabric intended for parachute decelerators, and to visualize damage formation in a carbon/epoxy tape-laminate intended for cryogenic propellant tanks. The fabric and laminate specimens are subjected to 1:1 and 1:2 biaxial tension-tension loading, respectively. The X-ray μCT images obtained during in-situ testing of the fabric specimen are used to measure the increase in fabric porosity and straightening of individual fibers. The X-ray μCT images of a biaxially-stressed tape-laminate specimen are used to document initiation and through-thickness evolution of closely-spaced intralaminar stitch cracks. Results from both experiments demonstrate that the new biaxial test enables observations of deformation and damage in advanced aerospace materials that have not been possible using more traditional surface-based observations.