The Rigid Body Collision Analysis Based On The Discrete Element Method

With the development of modern science and technology, many complex dynamics problems arise. Impact problem is always an important research field in Multi-body system, and often be encountered in the design of spacecraft and robots. How to accurately describe the collision problem of multi-body system has already become the basic research in many fields including aerospace, biotechnology, robotics and mechanical system and so on, and has very important practical significance.As the impact of multi body system with the short action time, strength and other characteristics, the process is very complex, especially when there is the friction factor in collision process. There are calculation results of the singularity, not stability, no solution or solution computation, large shortcomings in traditional multi-body dynamics method and finite element method. In this paper, we use the discrete element method, analyze several common discrete models and simulate the collision process by FORTRAN, and analyze the extent of the related factors in the collision process.In this paper, based on the discrete element theory, the rigid body collision is mainly analyzed. A program realization flow chart were given by using FORTRAN software programming based on the discrete element method and this paper detailed described and analyzed the Implementation process of Dynamic discrete element program between rigid collisions.Subsequently, the single point impact between the ball and the ground (including positive collision and obique collision) and multi-point collision of the three ball chain system were calculated and simulated by the process. And using the computed results obtained the velocity, displacement and motion state diagram of the collision body, and the curve between the overlap and contact force, and verfied the validity of the method presented in this paper.On the other hand, the influencing factors in the process of collision were obtained by analysis and comparison. The results show that recovery coefficient represented the up macro energy losses in the positive collision between the ball and the ground, the bigger the recovery coefficient is, the less the energy loss in the collision. When the tangential friction were considered in the oblique collision, changing the friction coefficient and angular volecity only changes the size of the friction, and does not affect the movement of collision process on the method direction. For the three ball chain system, the system state after the collision which has nothing to do with the displacement, quality and other factors is only affected by the mass and the stiffness ratio of collision body. These results were compared with theoretical and numerical algorithms, and consistent with their results, which verified the validity and reasonableness of the discrete element method to deal with the problem of rigid body collision.