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1

Determination of the stationary thermal state of simple geometry layered structures with themperature dependent heat conductivity factors

Makhorkin M, Makhorkin I., Makhorkina T.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2018

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Vol. 7, No 3

23--28

EN

An analytical-numerical method to determine the one-dimensional stationary thermal state of simple geometry multilayer structures for arbitrary dependences of heat-conductivity factors on temperature is proposed (the multilayer bodies of thermosensitive materials, referred to one of the classical orthogonal coordinate systems are considered, the thermal state caused by thermal load is characterized by a onedimensional stationary temperature field. Approbation of the methodology by studying the stationary thermal state of a two-layer cylinder is realized. The cases of existence of a closed-form analytic solutions for the nonlinear heat conduction problem are considered.

2

Analytical determination of the order of stress field singularity in some configurations of multiwedge systems for the case of antiplane deformation

Makhorkin M., Makhorkina T.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2017

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Vol. 6, No 3

45--51

EN

In this paper, the possibility of constructing the analytical expressions to determine the order of the stress singularities in multi-wedge composites of the most prevalent geometric configurations for the case of antiplane deformation is considered. Particularly, the analytical solutions of the corresponding characteristic equations are constructed for three-wedge systems whose components have such geometric characteristics [wzór] is а half-plane and attached to it wedges with the such apical angles: (in the presence and absence of a slit) [wzór] is а half-plane and attached to it wedges with such apical angles [wzór] (in the presence and absence of the slit with outlet angle to the linear materials interface) [wzór] is а half-plane and attached to it wedges with such apical angles [wzór]. The analytical solutions of characteristic equations for composite wedges composed of [wzór] elements with identical apical angles are constructed as well. Additional studies, the results of which have not been included in the materials of the article due to their inconvenience, indicate to that there are analytical solutions of the characteristic equation for a composite of this type with more elements. The obtained results make it possible to study the stress-strain state in multi-wedge systems of the considered configurations not restricting ourselves only to the vicinity of the wedges convergence point. In addition, the use of analytical solutions of characteristic equations in systems with a large number of wedges having the same apical angles gives the additional possibilities for analysis the angularly functionally graded materials.

3

Construction of integral equations describing limit equilibrium of cylindrical shell with a longitudinal crack under time-varying load

Makhorkin M., Nykolyshyn M

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2016

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Vol. 5, No 3

141--146

EN

The problem on limit equilibrium of a closed infinite cylindrical shell with a longitudinal crack under the action of time-varying load by the exponential law has been considered. According to presented conditions the expressions for the field of the stress-free deformations along the crack are presented in the form [wzory] are the operators identical to those given in [7] for the case of static load [wzory] and , are the operators that take into account the dependence of load on time. Using the same transformations that in the case of static load [7, 11], the key functions [wzory] are determined, and the clarification of the shell's stress-state is reduced to solving the system of singular integral equations (SIE). Its general form is similar to the same system constructed for static load [7], and the kernels of SIE have the form [wzory], where is a singular part [wzory], is a regular part in which the component [wzory] takes into account the time dependence of load [wzory], are described by the expressions similar to the same given in [7].

4

On determination of the stress-strain state of a multi-wedge system with thin radial defects under antiplane deformation

Makhorkin M., Sulym H.

Civil and Environmental Engineering Reports

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2010

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No. 5

235-249

EN

An elastic isotropic multi-wedge system with radially located thin defects under longitudinal shear is considered. The procedure of construction of asymptotics of the stress and displacement fields in the vicinity of the system apex using the apparatus of generalized functions and Mellin transform is presented. The notion of generalized stress intensity factor near the wedge system apex is introduced. The procedure proposed is applied to determine analytically the asymptotic distribution of stress and displacement fields in the three-wedge system peak. The generalized stress intensity factor near the three-wedge system apex is analyzed.

PL

Przedstawione badania dotyczą nowego podejścia do rozwiązywania zagadnienia antypłaskiego dla układu wieloklinowego z ułożonymi promieniowo cienkimi niejednorodnościami. Metoda ta, wykorzystuje podejście uogólnionego zagadnienia sprzężenia materiałów do modelowania istnienia cienkich defektów za pomocą funkcji skoków. To daje możliwość otrzymania w postaci analitycznej transformat Mellina naprężeń i przemieszczeń w pakietach z dowolną ilością klinów. Wskutek stosowania metody wyznaczenie stanu naprężeniowo-odkształceniowego w układzie klinowym podczas ścinania wzdłużnego sprowadza się do rozwiązywania jednego częściowo zdegenerowanego równania różniczkowego z odpowiednimi warunkami brzegowymi. Do jego rozwiązania stosuje się transformacja całkowa Mellina, której transformaty dla dowolnej ilości komponentów układu klinowego można znaleźć w postaci analitycznej. W wyniku przeprowadzonych badań zostały otrzymane asymptotyki naprężeń i przemieszczeń w otoczeniu wierzchołka układu klinowego oraz transformaty Mellina przemieszczeń. Wprowadzono pojęcie uogólnionego współczynnika intensywności naprężeń w wierzchołku klina oraz dla szeregu układów wieloklinowych otrzymano postać analityczną dla naprężeń i przemieszczeń w dowolnym punkcie kompozytu. Został również dokładnie zbadany przypadek obciążenia skupioną siłą układu z trzech klinów.

5

Singular stress in wedge system under antiplane strain conditions

Bozhydarnik V., Sulym G., Makhorkin M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2006

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z. 68 [231]

33-40

EN

Wedgy system composed of optional number of wedges and wedge-shaped notch under condition antiplane shear load is considered. Main attention is paid to the procedure of formulating equations for determination of the order if the system singularity in the tip periphery of the system by means of generalised functions and Mellin transforms. Detailed investigation of the order of singularity in the tip of three-wedge system under condition of the first, the second and combined problems of the theory of elasticity has been pursued.