PECULIARITIES OF APPLICATION OF ONE AND TWO-DIMENSIONAL FINISHED ELEMENTS IN MODELLING KINEMATICS OF PLASTIC FLOW OF METAL

Abstract

Designing of technological processes of volume stamping at the modern level involves solving a number of complex problems. The main purpose of the article is to use the laws of the deformation process to model the kinematics of plastic flow using modern software systems based on the finite element method. The obtained data will allow to form an information field of a specific technology and, thus, to be able to control both the process and the properties of products. These tasks include: determining the degree of deformation in the volume of the body and predicting the technological heredity of products; optimization of stamping transitions and prevention of technological failures. As a result of plastic deformation, especially cold, the material inherits uneven hardening and heterogeneity of properties in the volume of stamped products, which are the cause of residual stresses. Residual stresses can increase or decrease the strength of the product if it is not subjected to heat treatment after cold plastic deformation. The heterogeneity of the properties is due primarily to the uneven distribution of the accumulated deformation, the calculation of which in conventional technological practice is complicated. After pressure treatment, parts or workpieces are often annealed to relieve internal stresses and improve the structure of the metal. When designing technological processes with the use of computer modeling programs for plastic deformation processes, it is possible to choose such modes of deformation, which excludes the area of deformation that causes technological failures. In the processes of cold three-dimensional stamping, the possibilities of plastic deformation of metals are limited. Very often the deformations required to obtain products of the desired shape exceed the plasticity of the material - the degree of deformation at which a crack is formed under the conditions of this mechanical scheme of deformation. Therefore, it is necessary at the design stage of technological processes to establish whether the material will withstand the projected operation, which will lead to intensification of metalworking processes by pressure, as well as significant savings associated with reducing production experiments to adjust the process. Modern theory of plasticity allows to formulate and solve all these problems, however, given their complexity and connectivity, the result can be achieved only by using direct numerical methods, which in combination with high-speed computer equipment have created the preconditions for mathematical models of metalworking pressure and led to the emergence of appropriate programs, based in most cases on the finite element method.