In this paper, we experimentally and theoretically study the resistance force that develops when a cylinder with a flat face colliding against dry quartzite sand. Observations from experimental data clearly show that ...In this paper, we experimentally and theoretically study the resistance force that develops when a cylinder with a flat face colliding against dry quartzite sand. Observations from experimental data clearly show that the acceleration curves are characterized by a double-peak structure. The first agitated peak can be attributed to a shock process where sand responds elastically, and the valley bottom in the double-peak structure is related to a limited plastic load when a fully plastic region is formed in the sand, while the second agitated peak corresponds to a the occurrence of the maximum of viscous force in a homogeneous developed bulk flow. We use slip line theory (SL) developed in plastic mechanics to capture the value at the valley bottom, adopt the double shearing theory (DS), together with a Local Rheological Constitutive Law (LRCL) suggested in this paper, to capture the drag force generated in a homogeneous bulk flow. Good agreements in the comparisons between numerical and experimental results support the characteristic resistance by the cylinder to predict granular states.展开更多
In this paper, we base a theory established in an impulse-energy level to solve a problem of a disk-ball system, in which a moving ball collides perpendicularly against an disk staying on a horizontal surface. The imp...In this paper, we base a theory established in an impulse-energy level to solve a problem of a disk-ball system, in which a moving ball collides perpendicularly against an disk staying on a horizontal surface. The impact process is an ensemble consisting of a point impact coupled with a line contact between bodies of the disk, the ball and the fixed horizontal surface. We experimentally and theoretically show that the post-impact states of the disk dramatically vary with the impacting position of the ball. Explanations are given by investigating the evolutions of the potential energies resided in the points involved in the complex frictional impacts. Good agreements between numerical and experimental results strongly suggest that the evolution of energy together with the dissipation must be reflected in mathematical models if a precise description for the post-impact state of systems is expected.展开更多
基金the National Natural Science Foundation ofChina (Grant No. 11132001)
文摘In this paper, we experimentally and theoretically study the resistance force that develops when a cylinder with a flat face colliding against dry quartzite sand. Observations from experimental data clearly show that the acceleration curves are characterized by a double-peak structure. The first agitated peak can be attributed to a shock process where sand responds elastically, and the valley bottom in the double-peak structure is related to a limited plastic load when a fully plastic region is formed in the sand, while the second agitated peak corresponds to a the occurrence of the maximum of viscous force in a homogeneous developed bulk flow. We use slip line theory (SL) developed in plastic mechanics to capture the value at the valley bottom, adopt the double shearing theory (DS), together with a Local Rheological Constitutive Law (LRCL) suggested in this paper, to capture the drag force generated in a homogeneous bulk flow. Good agreements in the comparisons between numerical and experimental results support the characteristic resistance by the cylinder to predict granular states.
基金supported by the National Natural Science Foundation of China (Grant No.11132001)
文摘In this paper, we base a theory established in an impulse-energy level to solve a problem of a disk-ball system, in which a moving ball collides perpendicularly against an disk staying on a horizontal surface. The impact process is an ensemble consisting of a point impact coupled with a line contact between bodies of the disk, the ball and the fixed horizontal surface. We experimentally and theoretically show that the post-impact states of the disk dramatically vary with the impacting position of the ball. Explanations are given by investigating the evolutions of the potential energies resided in the points involved in the complex frictional impacts. Good agreements between numerical and experimental results strongly suggest that the evolution of energy together with the dissipation must be reflected in mathematical models if a precise description for the post-impact state of systems is expected.
