Selection of damping parameters usedin a particle flow code（PFC^2D）

Abstract：Simulations of a cantilever beam subject to combined action of shear-bending（a static problem） and rebound of a falling steel ball（a dynamic problem） were simulated by the particle flow code in 2-dimension（PFC2D,a discrete element software）,these two numerical simulations help to understand the selection principle and the influence law of damping parameters.The results show that local damping has no physical meaning and may be used in static or quasi-static problems to efficiently obtain the steady state solution.However,local damping parameter must be reduced to a physically realistic or only a reasonably viscous damping parameter should be used when simulating real dynamic physical phenomena by PFC2D.In the rebound of a falling steel ball test in PFC2D,the normal viscous-damping ratio of a steel ball is ζ=0.16.Damping parameters were important to PFC2D model,both computation time and numerical precision were determined by the damping and from the viewpoint of energy analysis,the action of damping can be represented by a damping energy（a kind of micro energy） dissipation mode.Therefore,PFC2D simulations coincide with theoretical or experimental results only when reasonable damping parameters are included in the numerical modeling.