Measurement of Local Stress and Strain in Schulze Tester using Pressure Sensitive Pads and X-Ray Tomography

摘要

Direct shear analysis is the most common method of measuring the yield locus of particulate powders [1, 2, 3]. Uniaxial shear analysis consists of two steps: consolidation to a state of continual deformation (with no volume change) followed by incipient yield. It is generally accepted that the consolidation is isotropic, hence inducing a condition in which the material has a uniform bulk density, porosity, and elasticity. However, this is not the case in the shear measurements conducted with the Schulze tester. Results demonstrated with pressure sensitive pads and x-ray tomography indicate that the consolidation is in fact anisotrophic, resulting in high and low density regions. By using microtomography and the pressure sensitive pads, it is possible to obtain a graphical representation of the formation, propagation, and movement of the shear region within the Schulze tester. Further evidence indicates that the anisotrophic behavior could be induced by the tester itself.