The Vibrating Feeder Of Discrete Element Numerical Analysis

This paper is introduced that the basic theory and development history of discrete element method. Distinct element method (DEM) is based on Newton's second law of motion and the basic law of particles between elements colliding. It's an effective numerical method which widely used in many engineering fields by using dynamic relaxation method on Iterative calculation. Contact model is the foundation of discrete element, by comparing the linear contact model and nonlinear contact model of DEM, select Cundall spring-damp-sliding contact model as our major studying model. Then do mechanics analysis on it, and derive a particularly coordinate system from mechanics formula, calculate the coordinate of the contact point, "composite quantity" of each contact unit and the relative velocity between units in this system.Do numerical simulation on the motion state of single granule on vibration surface, and when calculating amount by algorithm analysis, comparing the two ways of search about neighbors elements:Windows method and Zone method. While calculation, do research on the relationship between Insurance coefficient and Rigidity coefficient, and three kinds of ways of collisions---ompletely inelastic collision, completely plastic collision and elastic-plastic collision. We should also study on the relationship between recovery coefficient, contact rigidity and calculation time-step. Study on linear relationship between time-step and TCS with different rigidity parameters, and the nonlinear relationship between contact rigidity and the time of Collision contact; Based on the simulation results, the best recovery coefficient of collision is 0.5, and the best insurance coefficient is 0.1. Considering the self-reverence role of granule and the damping effect between granule and vibration plane, study the elastic collision, elastic-plastic collision and turning of granule on static vibration plane, and comparing the different parameters settings to its effects.At last, simply simulate the motion state of granule group after vibration box loaded, through defining an expansion coefficient which shows the loose degree of granule group, reflect the loose degree of coefficient of granule group increases as the recovery coefficient increases, and the recovery coefficient is affected by initial accumulation height of granule group on the vibration box. The influence friction factor give to the simulation results, is affected by initial accumulation height of granule group on the vibration box too. Although the bigger the contact rigidity is, the bigger the calculation time-step, lesser contact rigidity could also increase calculation time-step.