This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is define...This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by theMinkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowskioverlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternionbased orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures arobust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviourof a rockfill system under impact of a high speed projectile. The rockfill sample is generated by a three-dimensionalVoronoi meso method with a specific particle size distribution. The penetrating process of the projectile strikingthe rockfill target is simulated. Some physical quantities associated with the projectile such as the residual velocity,penetration resistance, and deflection angle are monitored which can reflect the influence of the characteristics ofthe rockfill target on its anti-penetration performance. It can be concluded that the developed polyhedral DEMmethod is a very promising numerical approach in analysing the dynamic behaviour of rockfill systems subject tohigh speed projectile impact.展开更多
The discrete element method(DEM)has become a powerful tool to investigate the breakage process,which has drawn increasing attention in recent years.The process of particle breakage can be regarded as the reduction of ...The discrete element method(DEM)has become a powerful tool to investigate the breakage process,which has drawn increasing attention in recent years.The process of particle breakage can be regarded as the reduction of the particle size,which results in the explosive growth of particle number,making the computation inefficient.Contact detection is a major process in DEM simulation.The cell size is a crucial parameter for contact detection and has a great influence on computational efficiency.The static cell size method is usually employed,and the size will be set before the simulation according to the particle size.Since the particle size changes during the breakage simulation,the static cell size method is no longer proper.As a result,a dynamic cell size method is proposed in this study.Two parameters are critical in this method that are key to the computational efficiency,including the number of neighbor particles retrieved for a specific particle(Np)and the number of search cells retrieved during the process of finding all neighbor particles(Nc).By integrating this new method,the cell size is supposed to be adjusted according to the ratio of Np to Nc to achieve a high efficiency of contact detection.By comparing the computational time of the same simulation case,the dynamic cell size method achieves substantial computational time reduction for equivalent simulation scenarios,and the efficiency under different cell sizes is recorded to validate the cell size in the subsequent test case.展开更多
基金This work is partially supported by National Natural Science Foundation of China under Grant No.12072217by Open Fund of State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology,Beijing,China[Grant No.SKLCRSM19KFA12].The support is gratefully acknowledged.
文摘This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by theMinkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowskioverlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternionbased orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures arobust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviourof a rockfill system under impact of a high speed projectile. The rockfill sample is generated by a three-dimensionalVoronoi meso method with a specific particle size distribution. The penetrating process of the projectile strikingthe rockfill target is simulated. Some physical quantities associated with the projectile such as the residual velocity,penetration resistance, and deflection angle are monitored which can reflect the influence of the characteristics ofthe rockfill target on its anti-penetration performance. It can be concluded that the developed polyhedral DEMmethod is a very promising numerical approach in analysing the dynamic behaviour of rockfill systems subject tohigh speed projectile impact.
基金supported by the National Natural Science Foundation of China(grant No.22078283).
文摘The discrete element method(DEM)has become a powerful tool to investigate the breakage process,which has drawn increasing attention in recent years.The process of particle breakage can be regarded as the reduction of the particle size,which results in the explosive growth of particle number,making the computation inefficient.Contact detection is a major process in DEM simulation.The cell size is a crucial parameter for contact detection and has a great influence on computational efficiency.The static cell size method is usually employed,and the size will be set before the simulation according to the particle size.Since the particle size changes during the breakage simulation,the static cell size method is no longer proper.As a result,a dynamic cell size method is proposed in this study.Two parameters are critical in this method that are key to the computational efficiency,including the number of neighbor particles retrieved for a specific particle(Np)and the number of search cells retrieved during the process of finding all neighbor particles(Nc).By integrating this new method,the cell size is supposed to be adjusted according to the ratio of Np to Nc to achieve a high efficiency of contact detection.By comparing the computational time of the same simulation case,the dynamic cell size method achieves substantial computational time reduction for equivalent simulation scenarios,and the efficiency under different cell sizes is recorded to validate the cell size in the subsequent test case.
