Abstract

X-ray computed tomography (XCT) is a reliable tool for measuring internal flaws and microstructural features in engineering materials. As an extension to XCT , Digital Volume Correlation (DVC) methodology enables tracking 3D deformation field based on local grayscale contrast. Nevertheless, its applicability and spatial resolution have been limited by the need for tracer particles or inherent microstructural features that are distributed in the material volume. To address these limitations, we developed a Flux Enhanced Tomography for Correlation (FETC) technique that leverages inherent inhomogeneities in engineering materials (polymers to metals) to measure all nine components of the deformation gradient without relying on artificial X-ray tracers. Via this unprecedented full-filed measurement technique, the mechanical behaviour of various engineering polymers was examined, and new observations was made on the well-established rubber elasticity. It was found that many polymers undergo significant local volume changes but the overall volume remains constant during mechanical loading. The presence of a mobile phase within the material volume has been proved which gives rise to negative local bulk moduli. By extending its application on other materials, FETC is expected to bring more electrifying discoveries of new material physics.