THE PERMEABLE ELEMENT METHOD FOR MODELING OF POWDER COMPACTION IN RIGID DIES

摘要

In investigations of production processes in which large strains are developed (e.g. powder compaction) it is often difficult to employ the traditionally used Lagrangian version of the finite element method (FEM) due to an excessive fragmentation of the network of finite elements. This deregularization necessitates regeneration of the network, which in turn prolongs calculation and substantially complicates the algorithm. For solving technological problems of this kind, it is more convenient to employ a permeable element method (PEM), which is an arbitrary Lagrangian-Eulerian version of the FEM. Basically, the method consists of using a network of finite elements of predetermined form, the mass of each element being variable due to exchange of powder between neighboring cells. The shape of the elements and network movement are deliberately determined from the point of view of convenience for the analysis of the calculation results. Using the PEM, the pressing of hollow cylinders in a rigid die is considered. The computed spatial density distributions are compared with experimental data obtained, using quantitative metallography analysis. The problem of pressing an article of a stepped shape is solved. The peculiarities of material flow and density distributions are discussed.