Volodymyr Mykhalevych

Vinnytsia National Technical University · Higher mathematics

The processes of planting blanks by the rolling stamping method allow for the efficient production of a wide range of high-quality products, but the possibility of material destruction during deformation prevents the expansion of their technological capabilities. Further development of the processes is possible through the development of new techno...

The processes of planting blanks by the rolling stamping method allow for the efficient production of a wide range of high-quality products, but the possibility of material destruction during deformation prevents the expansion of their technological capabilities. Further development of the processes is possible through the development of new techno...

Розглянуто задачу визначення граничної накопиченої деформації до руйнування матеріалу для окремого класу зміни швидкості деформацій відповідно до лінійних дволанкових траєкторій. Всі траєкторії відповідають таким вимогам: в початковий момент швидкість деформації дорівнює нулю, досягає максимального значення в точці зламу та зменшується впродовж дру...

A process for producing hardmetal cutting plates (synthetic cutting tool material) has been developed and implemented. It is established that the most rational and economically sound option is to introduce several die toolings with relevant service features in the manufacture of products by self-propagating high-temperature synthesis. Advantages of...

A compaction process using self-propagating high-temperature synthesis (SHS) has been developed. The process includes preparation of a composite powder billet in conditions that promote uniform pore distribution over the synthesized product, followed by barothermal SHS and compaction of the billet by plastic deformation. To determine the ultimate s...

The authors have elaborated mathematical models and information technologies for the experimental-analytical determination of stress-strain state and ultimate accumulated strain in a material on a barreled side surface of a cylindrical specimen under edge compression. A model that allows one to predict the ultimate accumulated plastic strain has be...

The paper gives the research findings which make it possible to construct an algorithm for the residual life assessment within the framework of a tensor approach to describing damage in a material under inelastic deformation. The authors propose explicit finite criterial relationships for the residual life assessment, which extend the known relatio...

It is proposed to formulate strength criteria as a relationship between the stress intensity and dimensionless invariant ?, which is equal to the ratio of the first stress-tensor invariant to the stress intensity. The use of the ? invariant in the case of plane stress is proved to be correct. A comparison of calculated and experimental data demonst...

We suggest the strength criterion represented in form of the dependence of the stress intensity on the infinite invariant η given by the relation of the first stress tensor invariant to the intensity of stresses. The proof of reasonable application of the invariant η to the case of plane stress is given. By correlations between the calculated and e...

New tensor models are used to obtain criterional relations for the class for loadings consisting of two or more stages. The relations are analyzed and compared with the known experimental data. They describe rupture strength in the case when constant stresses ij(1), ij(2) act during the first and second stages. An analytical description is present...

The criterial relationships as applied to class of two-step and multi-step loadings are obtained on the base of tensor models. An analytical description of experimental data for endurance limit of copper, aluminum alloy and EI437B alloy specimens is presented under multi-step loading conditions with combined tension and torsion of cylindrical speci...

Criterional relations are obtained from a model constructed to describe isoperimetric processes in two- and multi-step loading, as well as stepped loading with pauses. An analysis is made of the laws governing the accumulation of damages during these processes, which are special cases of proportional loading. A comparative analysis is made of crite...

The results of testing the specimens of KhN70VMTYu alloy, 316 steel, EI826 alloy under two-stepped loading at 800, 550, 800°C respectively are considered. The regularities of damage accumulation and the criterial relations are analyzed. An analogy of the criterial relations describing the damage accumulation in the creep process and in the high-tem...

A relationship is established between the rupture-strength theory of Il'yushin and the Pisarenko—Lebedev criterion. The variant proposed for constructing tensor models of rupture strength is based on prior knowledge of the rupture-strength surface — the dependence of the time to fracture under steady loading on stress intensity and other dimensionl...

A tensor model of damage accumulation is suggested in order to determine limiting strains. Clear criterial dependences are established as applied to symmetric, asymmetric, and block deformation regimes. The relationships obtained are analyzed quantitatively and qualitatively, and they are compared with experimental data.

A tensor model of damage accumulation to define ultimate strain is proposed. Explicit criterion-type relationships are established as applied to symmetric, asymmetric, and block regimes of straining. The relations obtained have been analyzed both quantitatively and qualitatively and compared with the experimental data, obtained for 07Kh25N13 austen...

Mechanisms of the hot-forming property of alloy VT9 and steel 13Kh11N 2V2MF-Sh are investigated. Heating of the deformation zone is shown to be responsible for a positive deformation mode. The longer the time interval, and the higher the severity of damage and the strain rate, the larger is the value of plasticity recovered within the interval. An...

The effect of superficial plastic working has been studied on the intensity of cumulative damage in VT8, VT9, VT25, Ep718 and OT4 alloys. The technique is developed for estimating their deformability. A mathematical model is suggested to determine the value of the used life of the blank surface layer material. Advises are given to improve the surfa...

Models for media with initial anisotropy of limiting deformations were generalized. It was shown that the model of isotropic defects accumulation accounting the initial anisotropy of limiting deformations, was in conflict with available experimental data on two-stage deformation. It is expected that the degree of reliability and the limits for appl...

Linear model of damage accumulation under simple and cyclic deformations, quasi-linear and tensor-nonlinear models are considered. The model of ultimate strains during hot deformation is presented. Process of hot deformation is thermodynamically non- equilibrium. The accumulation of damages in metal is accompanied by their healing at a time. The sy...