In this paper,through experiments and DEM simulations,it is found that there is a ring-shaped region named Quasi-static Region between the particles expanding outward and the particles collapsing inward during the imp...In this paper,through experiments and DEM simulations,it is found that there is a ring-shaped region named Quasi-static Region between the particles expanding outward and the particles collapsing inward during the impact process.Quasi-static Region is always generated from the impact point at the same time,and then spreads out at a uniform speed.During the propagation of Quasi-static Region,the velocity of the particles in the particle extend region varies linearly in space and time.And the change rate is only related to the properties of the particle system.The simulation results show that the particle flow in Quasi-static Region is elastic-inertial flow,while the particle flow expanding outward and collapsing inward is inertial flow.展开更多
Granular matter is the second most handled material after water in the global industry.Its macroscopic behavior arises from a collisional to a collective motion of the constituent grains,with varying lengths and time ...Granular matter is the second most handled material after water in the global industry.Its macroscopic behavior arises from a collisional to a collective motion of the constituent grains,with varying lengths and time scales.The fluid-like and solid-like behaviors of granular materials and their transitions[1]are relevant to many industrial problems,such as mining excavation[2],selective laser sintering and powder spreading[3],thawing-induced slope failure[4],and granular impact[1].Designing and optimizing these processes require a synergy of understandings obtained from studies of contact theories[5],particle morphology or shape representation[5,6],interparticle friction[7],and micro-tomacro[4,7,8]and discrete-to-continuum transitions[1,2].展开更多
The motion of a projectile impact onto a granular target results in both the resistance force exerted on the projectile and rheology of granular media.A horizontal arrangement of cylinder quasistatically and dynamical...The motion of a projectile impact onto a granular target results in both the resistance force exerted on the projectile and rheology of granular media.A horizontal arrangement of cylinder quasistatically and dynamically intruding into granular media under different velocities and angles is simulated using discrete element method.Three distinguished drag force regimes are exhibited,including hydrostatic-like force independent of velocity,viscous force related to velocity,and inertial drag force proportional to the square of velocity.Meanwhile,the influence of penetration angles on drag force is examined for these three regimes,and a force model,which is related to penetration depth and angle,is proposed for quasi-static penetration.Then,flow characteristics of the granular media,such as velocity field,pressure field,packing fraction etc.,are traced,and a rheology model of packing fraction and inertial number is established.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11502104,11872029,and 12172156)Ministry of Education,the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2021-56)the Natural Science Foundation of Gansu Province(Grant No.17JR5RA206).
基金This work was supported by the National Natural Science Foundation of China(grant No.12072200)the Science and Technology Commission of Shanghai Municipality(grant No.19142201500).
文摘In this paper,through experiments and DEM simulations,it is found that there is a ring-shaped region named Quasi-static Region between the particles expanding outward and the particles collapsing inward during the impact process.Quasi-static Region is always generated from the impact point at the same time,and then spreads out at a uniform speed.During the propagation of Quasi-static Region,the velocity of the particles in the particle extend region varies linearly in space and time.And the change rate is only related to the properties of the particle system.The simulation results show that the particle flow in Quasi-static Region is elastic-inertial flow,while the particle flow expanding outward and collapsing inward is inertial flow.
文摘Granular matter is the second most handled material after water in the global industry.Its macroscopic behavior arises from a collisional to a collective motion of the constituent grains,with varying lengths and time scales.The fluid-like and solid-like behaviors of granular materials and their transitions[1]are relevant to many industrial problems,such as mining excavation[2],selective laser sintering and powder spreading[3],thawing-induced slope failure[4],and granular impact[1].Designing and optimizing these processes require a synergy of understandings obtained from studies of contact theories[5],particle morphology or shape representation[5,6],interparticle friction[7],and micro-tomacro[4,7,8]and discrete-to-continuum transitions[1,2].
基金support for this work from National Natural Science Foundation of China(grant Nos.11502104,11872029,12172156)Ministry of Education,the Fundamental Research Funds for the Central Universities(grant No.lzujbky-2021-56)the Natural Science Foundation of Gansu Province(grant No.17JR5RA206).
文摘The motion of a projectile impact onto a granular target results in both the resistance force exerted on the projectile and rheology of granular media.A horizontal arrangement of cylinder quasistatically and dynamically intruding into granular media under different velocities and angles is simulated using discrete element method.Three distinguished drag force regimes are exhibited,including hydrostatic-like force independent of velocity,viscous force related to velocity,and inertial drag force proportional to the square of velocity.Meanwhile,the influence of penetration angles on drag force is examined for these three regimes,and a force model,which is related to penetration depth and angle,is proposed for quasi-static penetration.Then,flow characteristics of the granular media,such as velocity field,pressure field,packing fraction etc.,are traced,and a rheology model of packing fraction and inertial number is established.
