OS3-1-2 Measurement of 3-D strain distribution based on tracking of microstructural features in high-resolution SR-CT image

A tracking procedure for the high-resolution X-ray computed tomography has been developed in order to measure 3-D local strain within a deforming material in high-density. A model sample, which made of a dispersion-strengthened copper with alumina particles and contains artificial micro-pores, was visualized by the synchrotron radiation computed tomography (SR-CT) with in-situ test rig. Tensile loading was applied to the sample step by step. High-resolution tomographic experiment was performed at the third-generation synchrotron radiation facility (SPring-8) in Japan. Gravity center position, volume and surface area in the pores, which were regarded as markers in a tracking procedure, were measured by 3-D digital image analysis. The markers before and after the deformation were provided for registration and macroscopic strain correction before the tracking procedure. The marker tracking was carried out by means of matching parameter that was described as functions of distance, volume and surface at markers. The developed tracking method indicated high tracking ratio and tracking success ratio, which was approximately 100%, up to the macroscopic strain level that exceed in the strain range of practical tracking experiment. The 3-D strain distribution was represented successfully by the tracking results. A combination of high-resolution SR-CT and tracking of microstructural features is effective to visualize interior strain distribution in materials in 3-D.