Simple shear simulation of 3D irregularly-shaped particles by image-based DEM

This paper describes an image-based DEM taking account of the irregular shape of solid particles in a direct manner. A micro X-Ray CT at SPring-8 (a synchrotron radiation facility in Japan) was employed to obtain high quality CT images for detecting correctly the shape of particles. The digitized 3D shape data of each particle was automatically obtained by an original image-processing technique. The particle shape was modeled by a cluster of several spherical elements using dynamic optimization method. The accuracy of the modeling can be controlled by the number of elements forming each particle. Using such modeled particles a series of simple shear simulations were performed for the specimens with various void ratios. It was found that 10-element model can quantitatively reproduce the shear behavior of relatively-dense specimens. On the other hand, in order to well simulate the packing structure and the shear behavior of loose specimens, 10-element model is found to be insufficient and more accurate model would be necessary. This result implies that the overall grain shape that is relevant to the moment transmission between grains is important in densely-packed granular assembly, while small surface angularity plays considerable role in loosely-packed granular assembly.