FEM-DEM coupling analysis for solid granule medium forming new technology

Solid Granule Medium Forming (SGMF) is a new flexible die forming technology which uses solid granules as the soft die to form the sheet metal. The process numerical analysis of this technology involves the discrete element (granules) and the continuum solid element (sheet metal), as they belong to different solving system-the discrete element method (DEM) solving system and finite element method (FEM) solving system, now there is no effective simulation ways for this kind of problems. Based on this, this paper established a new FEM-DEM coupling method according to the force conservation principle. And the simulation platform based on this method is developed through Visual Basic, which can realize the interaction, inheritance and transmission of the calculating data between FEM and DEM, with it the problems of elastic-plastic mechanics in the contact between continuum and discontinuum are solved for the first time. Such as the influence laws of the shape and mechanical parameters of discrete object on the plastic deformation of the continuum could be obtained. The limitations and errors brought by using FEM alone to analyze the fission problems are also eliminated by this. Solid granule medium tube outer pressure compression forming is used as a carrier to build the FEM-DEM coupling model, with the simulation platform both the force transmission characteristics and the mesostructure variation rule of solid granule medium in the tube forming process were obtained, and the impacts of technical parameters on the plastic forming property of the tube were analyzed. The accuracy of FEM-DEM coupling method is proved by the forming tests. This article provides an efficient way to solve the coupling deformation problems between the continuum and discontinuum in the field of engineering and a good experience for the solution of complicated engineering problems which need to be worked out with the secondary development of software.