Experimental study of anisotropy and non-coaxiality of granular solids

Abstract

Previous experimental studies of anisotropy and non-coaxiality by using the hollow cylindrical apparatus are mainly focused on granular soils, which feature irregular particle shapes and non-uniform particle size distributions. This paper experimentally investigates these two characteristics on assemblages of particulate materials with regular particle shapes and uniform particle sizes. These assemblages are made from spherical, cylindrical and cubical particles, with an increasing order of particle angularity. Two types of loading paths in the hollow cylindrical apparatus are applied. One is the monotonic loading path with a range of fixed angles of major principal stress with respect to the horizontal bedding plan, used to investigate the anisotropy of materials. The other is the path of pure principal stress rotations, used to study the non-coaxiality. The experimental results indicate that these three materials exhibit a strong anisotropy and non-coaxiality. Their stress-strain responses are dependent on the orientation of major principal stress. The non-coaxiality is a function of stress ratio. In addition, there is a noticeable trend that these two characteristics are dependent on the angularity of particles. The more angular the particles are, the greater anisotropy and non-coaxiality take place.

Effect of Particle Size and Cohesion on Powder Yielding and Flow

“…Interesting granular phenomena like yielding and jamming (Liu and Nagel, 1998;Bi et al, 2011;Luding, 2016;Kumar and Luding, 2016), dilatancy (Cates et al, 2005;Van Hecke, 2009;Yang et al, 2015), shear-band localization (Alshibi and Sture, 2000;Singh et al, 2014), history-dependence (Thakur et al, 2014), and anisotropy (Radjai et al, 1996;Majmudar and Behringer, 2005) have attracted significant scientific interest over the past decades (Savage and Hutter, 1989;Cundall, 1989;Radjai et al, 1999;Wolf et al, 2000;† GDR-MiDi, 2004;Tomas, 2005;Alonso-Marroquin and Herrmann, 2004;Luding 2005aLuding , b, 2008. Various laboratory element tests can be performed to study the bulk behaviour of granular materials (Schwedes, 2003).…”

Investigation of influence of particle characteristics on the non‐coaxiality of anisotropic granular materials using DEM

“…Many researchers have studied the non‐coaxiality of granular media by experimental tests, theoretical analyses, and numerical simulations . As a result of the deposition process and grain characteristics, a granular soil can be inherently anisotropic .…”

“…Many researchers have studied the non‐coaxiality of granular media by experimental tests, theoretical analyses, and numerical simulations . As a result of the deposition process and grain characteristics, a granular soil can be inherently anisotropic . Experimental studies have strongly suggested that the inherent anisotropy contributes to the key aspects of many macroscopic sand responses, including dilatancy and non‐coaxiality .…”

“…As a result of the deposition process and grain characteristics, a granular soil can be inherently anisotropic . Experimental studies have strongly suggested that the inherent anisotropy contributes to the key aspects of many macroscopic sand responses, including dilatancy and non‐coaxiality . Cai et al examined the non‐coaxial behavior using two different sands (Portaway sand and Leighton Buzzard sand).…”

“…Their experimental results both showed that the sands with larger aspect ratio and angularity exhibited larger non‐coaxial angles under the same stress condition. Yang et al experimentally investigated the anisotropy and non‐coaxiality of particulate materials with non‐spherical particle shapes and uniform particle sizes. Their experimental results indicate that the more angular the particles are, the greater anisotropy and non‐coaxiality take place.…”