Numerical Study of a Granular Material in Various Gravity Environments

This paper presents the material response of a granular material under different gravity fields using the discrete element method (DEM). A bidispersive porous medium is prepared and sheared under various gravity conditions. The medium is composed of two kinds (shape and size) of ellipsoids. Each type of particle occupies 50% of the whole mass. The ellipsoids are randomly generated and deposited in lunar gravity (1/6g), Earth’s gravity (1g), and elevated gravity (10g). Various friction coefficients are used during the deposition stage, which yields samples of different initial densities. Afterward, samples are isotropically consolidated to different initial confining pressures, and the friction coefficient between particles is 0.5. A total of 25 numerical samples have been created. Very large strain is applied to the sample under drained or undrained conditions. The granular material comes into the critical state. Overall, the gravity effect on peak friction angle (shear strength of the material) is negligible. The critical states of all samples are very similar. There is one observed gravity effect; a greater level of gravity produces samples of higher coordination number.