We investigate the distribution of contact forces in a static granular system and in annular shear granular flow, using the discrete element method, and considering the influences of both packing fraction and friction...We investigate the distribution of contact forces in a static granular system and in annular shear granular flow, using the discrete element method, and considering the influences of both packing fraction and friction coefficient. We find the existence of a critical packing fraction. If the packing fraction is lower than this critical value, all contact forces in granular system vanish. For shear granular flow, the criti- cal packing fraction is significantly smaller than that for static granular system. The distribution of the contact forces also exhibits different forms, especially at lower packing fraction. We also investigate the spatial configuration of contact network using the angular distribution of contact forces. In static granular systems, the contact force network is approximately isotropic, while in shear granular flow, it exhibits a distinct anisotropy along the shear direction. 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.展开更多
The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with variou...The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with various particle size dispersities was studied using the discrete element method. The study addressed packing density, coordination number, contact forces, global stress, and energy dissipation in assemblies composed of frictional spheres. Packing density was found to change with increasing num- ber of granulometric fractions in mixtures with a small ratio of the diameters of the largest to smallest particles. Results indicated a certain value of particle size ratio below which the number of particle size fractions strongly affected packing density. The average coordination number decreased with increasing number of fractions. Detailed analysis of the effect of particle size dispersity on mechanical coordination number, including particles with no less than four contacts, revealed that, contrary to the average coordi- nation number, the mechanical coordination number increased with increasing ratio of the diameters of the largest to smallest particles in the sample. The composition of polydisperse samples strongly affected stress distribution and energy dissipation in granular packings.展开更多
基金supported by the Key Project of the National Natural Science Foundation of China (Grant No. 10532040)the Program of Changjiang Scholars and Innovative Research Team in University (Grant No. IRT 0628)
文摘We investigate the distribution of contact forces in a static granular system and in annular shear granular flow, using the discrete element method, and considering the influences of both packing fraction and friction coefficient. We find the existence of a critical packing fraction. If the packing fraction is lower than this critical value, all contact forces in granular system vanish. For shear granular flow, the criti- cal packing fraction is significantly smaller than that for static granular system. The distribution of the contact forces also exhibits different forms, especially at lower packing fraction. We also investigate the spatial configuration of contact network using the angular distribution of contact forces. In static granular systems, the contact force network is approximately isotropic, while in shear granular flow, it exhibits a distinct anisotropy along the shear direction. 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
文摘The role of number of grain size fractions on structural and mechanical properties of uniaxially com- pressed granular packings with a uniform particle size distribution in terms of number of particles and with various particle size dispersities was studied using the discrete element method. The study addressed packing density, coordination number, contact forces, global stress, and energy dissipation in assemblies composed of frictional spheres. Packing density was found to change with increasing num- ber of granulometric fractions in mixtures with a small ratio of the diameters of the largest to smallest particles. Results indicated a certain value of particle size ratio below which the number of particle size fractions strongly affected packing density. The average coordination number decreased with increasing number of fractions. Detailed analysis of the effect of particle size dispersity on mechanical coordination number, including particles with no less than four contacts, revealed that, contrary to the average coordi- nation number, the mechanical coordination number increased with increasing ratio of the diameters of the largest to smallest particles in the sample. The composition of polydisperse samples strongly affected stress distribution and energy dissipation in granular packings.
