Numerical Simulation Of Impact Failure Of Bar Structures Based On Discrete Element Method

The collapse of single-layer latticed shells always involves the strong nonlinear mechanical behaviors,such as large deformation,contact,fracture and collision.When the strong nonlinear issue is resolved by finite element method,the singular stiffness matrix may lead to the non-convergence.Because of the demand of the deformation compatibility equations,It is difficult to describe the whole collapse process of structures by using the finite element method.The basic principle of the discrete element method is to divide the simulation object into several rigid elements.The force transfer between elements is determined by the force-displacement criterion.The motion of the ball is determined according to Newton’s second law.The model does not have to satisfy the displacement continuity condition and deformation compatibility condition,when using the discrete element method to simulate the model.It is suitable for dealing with the problems of large deformation,contact and collision.The discrete element method is widely used in the field of geotechnical engineering.In this paper,based on the basic model of the discrete element software PFC3D,the method of setting the parameters of the discrete element is given.In this paper,based on the basic contact model of discrete element software PFC3D,the method of setting the parameters of discrete element which is suitable for dealing with the problems of bar structure is given.The feasibility of the method is verified by using the method to simulate the large deformation of cantilever beam.PFC3D assumes that the contact is directly broken after reaching a certain strength.To overcome this problem,layered beam theory is introduced into PFC3D.The criterion of plasticity and the method of setting the contact parameter are given when the material turns into plasticity.It is possible to use PFC3D to solve the elastoplastic problem of the bar structure.At the same time,the fracture criterion of the parallel bond is improved,so that it is possible to simulate the fracture behavior of the bar.In this paper,the contact model suitable for the collision problem is selected and the method of setting the parameters of the contact model is given.Finally,the finite element method is used to simulate the collapse behavior of reticulated shell,and the correctness of the method is verified.