| The failure modes of sand are governed by a combination of simple mechanisms like sliding, rolling, and local deformation of grains. However, the aggregate mechanical behavior is complex because of the number of particles and the intricate dynamics involved. An important goal of analyzing failure mechanisms is to connect the failure mode, mechanical strength, and behavior of sand particles under compression to analytical and finite element models. The current experiment investigates sand failure under increasing strain using in-situ tomography. A software procedure was developed improving the quality and efficiency of the reconstructed images, and for visualizing and understanding crack propagation in the sand grains at a multitude of in-situ strain steps. X-ray computed tomography was used to directly observe strain localization, shear band formation, and the deformation of sand particles under applied load. Deformation modes were observed macroscopically across many grains and microscopically within the grains. The results are useful to validate and develop mechanical models. |
