Construction of Curve Boundary Deformations of Metals

Abstract

The work deals with the problems of studying the plasticity of metals, which are associated with the lack of methods of constructing a "single" curve of limit deformations due to the formation of a neck during stretching of samples and the formation of a barrel during deposition, and at the same time, the increase in plasticity due to the implementation of complex deformation. The purpose of this work is to develop a technique for constructing curves of limit deformations of metals with simple deformation and a constant value of the stress state indicator and to use them for objective assessment of the deformability of the material of the workpieces in the technological processes of plastic molding. The main method of research is an experiment with the creation of controlled and controlled conditions for the deformation of samples. In addition, an experimental and computational method was considered, which involves the construction of deformation paths during the deposition of cylindrical samples and the correction of the limit deformation using the deformability criterion. We found that during stretching, in the case of neck formation, the increase in deformation depends linearly on the ratio of the radius of curvature of the neck to its diameter. An equation is presented, which can be used to take into account the effect of the neck on the increase in limit deformations using the experimental and computational method. A method of rolling a cylindrical sample into a wedge with rolls, the radii of which increase during the rolling process, has been developed. The method provides the possibility of testing cylindrical samples under constant stress and allows obtaining values of plasticity under conditions of uniaxial tension. Curves of limit deformations, with the precision necessary for practice, are proposed to be built based on the results of testing samples for torsion and settling using an approximate dependence. Curves of limit deformations of a number of steels were constructed according to the given method. The resulting curves of limit deformations are constructed excluding the influence of the deformation history on them and can be used for objective evaluation of the deformability of the workpiece material in technological processes.

Investigation of Stamping by Wrapping Processes Through Material Deformation Modeling Analysis

“…Отже, розглянемо скалярні та тензорні моделі. Використанню скалярних моделей підсумовування пошкоджень для розв'язання задач оцінки деформовності заготовок при технологічних процесах обробки тиском присвячено низка праць [8].…”

“…відповідають стаціонарному деформуванню. В[8, 9, 10] отримано експериментальні та розрахункові дані стосовно лінійних траєкторій виду: розтягом з крученням суцільних циліндричних зразків. Представлено результати визначення напружено-деформованого стану матеріалу небезпечної зони заготовки під час ротаційного кування.…”