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卷 57, 编号 5 (2016)

Article

Nonclassical models of the theory of plates and shells

Annin B., Volchkov Y.

摘要

Publications dealing with the study of methods of reducing a three-dimensional problem of the elasticity theory to a two-dimensional problem of the theory of plates and shells are reviewed. Two approaches are considered: the use of kinematic and force hypotheses and expansion of solutions of the three-dimensional elasticity theory in terms of the complete system of functions. Papers where a three-dimensional problem is reduced to a two-dimensional problem with the use of several approximations of each sought function (stresses and displacements) by segments of Legendre polynomials are also reviewed.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):769-776
pages 769-776 views

Bonds between metals and nanocomposites created by explosion welding

Bondar’ M., Karpov E., Lukyanov Y.

摘要

This paper describes the study of the influence of a microstructure characterized by directed or chaotic distribution of nanoinclusions and strain rate on the deformability of nanocomposites. It is revealed that, under identical loading conditions, cracks are formed in nanocomposites whose structural elements are mostly directed in the same way at lower strain rates than in nanocomposites with chaotic distribution of the reinforcer. It is shown that, as the strain rate increases, the influence of the structural order on the limiting deformation reduces due to transition from shear strain to rotational strain. No cracks are formed in the creation of bonds between metals and nanocomposites by explosion welding. The experimental results obtained in the study of transverse bending of two-layer welded beams and the structure in the vicinity of the weld reveal that the obtained metal–nanocomposite bond has a uniform structure retained in deformation, with fracture occurring in the nanocomposite.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):777-783
pages 777-783 views

On the load-carrying capacity of structural members

Van’ko V.

摘要

Various approaches to determining the load-carrying capacity of beams and shells under elastoplastic deformation and creep deformation conditions are analyzed.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):784-788
pages 784-788 views

Experimental study of the inelastic behavior of materials

Vasin R.

摘要

This paper presents the results of an experimental study of the elastic and viscoplastic properties of alloys using elastoplastic theory. The need to study complex loading of materials, consider the microstructure evolution during deformation, and develop an appropriate experimental design theory and adequate constitutive relations is highlighted.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):789-791
pages 789-791 views

Influence of the cross-sectional shape of tensile bars on their creep rupture strength in a corrosive medium

Lokoshchenko A., Fomin L.

摘要

The creep rupture strength of tensile bars in a corrosive medium is studied. The time to failure of the bars is analyzed as a function of their cross-sectional shape. It is shown that the influence of the corrosive medium on the creep rupture strength of the bars is determined by the diffusion of its elements into the bar material, resulting in a decrease in its creep rupture strength. The diffusion of the corrosive medium into a bar is studied using an approximate method for solving the diffusion equation taking into account the motion of the diffusion front. Bars with different cross-sectional shapes are considered using Rabotnov kinetic theory. It is shown that at the same tensile stress, the bar with a circular cross-section has minimum time to failure.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):792-800
pages 792-800 views

Version of the linear elasticity theory with a structural parameter

Revuzhenko A.

摘要

It is shown that, in the planar case, the system of constitutive equations of the linear elasticity theory should contain five independent equations. In the classical theory, only three equations are formulated, while the other two are contained in implicit form in the postulate of diffeomorphism, which is the assumption of smoothness of the displacement field. A closed elasticity model is constructed without the assumption of diffeomorphism, and it contains a structural parameter having a dimension of length. It is shown that, in a static version, macrodeformations depend on stresses and second derivatives of stresses with respect to the coordinates, while there is dispersion of longitudinal and transverse waves in the dynamics.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):801-807
pages 801-807 views

Analyzing the deformation of a porous medium with account for the collapse of pores

Sadovskii V., Sadovskaya O.

摘要

The generalized rheological method is used to construct a mathematical model of small deformations of a porous media with open pores. Changes in the resistance of the material to external mechanical impact at the moment of collapse of the pores is described using the von Mises–Schleicher strength condition. The irreversible deformation is accounted for with the help of the classic versions of the von Mises–Tresca–Saint-Venant yield condition and the condition that simulates the plastic loss of stability of the porous skeleton. Within the framework of the constructed model, this paper describes the analysis of the propagation of plane longitudinal compression waves in a homogeneous medium accompanied with plastic strain of the skeleton and densification of the material. A parallel computational algorithm is developed for the study of the elastoplastic deformation of the porous medium under external dynamics loads. The algorithm and the program are tested by calculating the propagation of plane longitudinal compression shock waves and the extension of the cylindrical cavity in an infinite porous medium. The calculation results are compared with exact solutions, and it is shown that they are in good agreement.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):808-818
pages 808-818 views

Optimal shapes of axisymmetric bodies penetrating into soil

Kotov V., Linnik E., Tarasova A.

摘要

This paper presents the results of a study of the shapes of axisymmetric bodies with minimum drag and maximum depth of penetration into the plastic soils. Optimal shapes of bodies of revolution of given length and cross-sectional radius with generatrices represented by line segments are obtained by a modified method of local variations. The problem is solved using a binomial quadratic model of local interaction, including inertial and strength terms containing constant and Coulomb frictions. The drag forces and the penetration depth of cones and the obtained bodies of optimal shape are determined at different penetration velocities.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):819-827
pages 819-827 views

Green’s function for a prestressed thermoelastic half-space with an inhomogeneous coating

Belyankova T., Kalinchuk V.

摘要

A mathematical model is developed for an inhomogeneous thermoelastic prestressed half-space consisting of a stack of homogeneous or functionally graded layers rigidly attached to a homogeneous base. Each component of the inhomogeneous medium is subjected to initial mechanical stresses and temperature. Successive linearization of the constitutive relations of the nonlinear mechanics of a thermoelastic medium is performed using the theory of superposition of small deformations on finite deformations with the inhomogeneity of the medium taken into account. Integral formulas are derived to explore dynamic processes in inhomogeneous prestressed thermoelastic media.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):828-840
pages 828-840 views

Free vibrations of circular cylindrical shells with a small added concentrated mass

Leizerovich G., Seregin S.

摘要

The effect of a small added mass on the frequency and shape of free vibrations of a thin shell is studied using shallow shell theory. The proposed mathematical model assumes that mass asymmetry even in a linear formulation leads to coupled radial flexural vibrations. The interaction of shape-generating waves is studied using modal equations obtained by the Bubnov–Galerkin method. Splitting of the flexural frequency spectrum is found, which is caused not only by the added mass but also by the wave-formation parameters of the shell. The ranges of the relative lengths and shell thicknesses are determined in which the interaction of flexural and radial vibrations can be neglected.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):841-846
pages 841-846 views

Viscoelastic problem for piecewise homogeneous piezoelectric plates

Kaloerov S., Samodurov A.

摘要

The electromagnetoviscoelastic problem is solved for piecewise-homogeneous plates. The problem is reduced to solving a sequence of electromagnetoelastic problems with complex potentials. General representations of approximation functions for multiply connected domains and boundary conditions for their determination are given. An analytical solution of the problem for a plate with one inclusion and an approximate solution for a plate with a finite number of inclusions are obtained. The change in the electromagnetoelastic state is investigated numerically as a function of time, the properties of the plate and inclusion materials, and the distance between the inclusions.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):847-858
pages 847-858 views

Influence of hydrogen on the strength and ductility of 30KhGSA and EI659 steels in quasi-static and shock-loading tests

Ogorodnikov V., Yukhimchuk A., Mochalov M., Andramanov A., Baurin A., Blikov A., Boitsov I., Erunov S., Maksimkin I., Malkov I., Pupkov A., Shevnin E.

摘要

The influence of hydrogen on the strength and ductility of 30KhGSA and EI659 steels in quasi-static and shock-loading tests was studied experimentally. The sensitivity of the steels to hydrogenation in air under normal pressure or in hydrogen at a pressure of 25 MPa was determined from the results of tests of as-received and pre-hydrogenated samples at a temperature of 773 K and a hydrogen pressure of 50 MPa for 24 h. It is found that EI659 steel doped with tungsten and vanadium is less sensitive to hydrogenation than 30KhGSA steel doped with manganese and chromium.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):859-865
pages 859-865 views

Explosive loading of deformable gas-permeable axisymmetric structural elements

Glazova E., Konstantinov A., Kochetkov A., Krylov S.

摘要

A mathematical model is proposed which describes the interrelated processes of unsteady elastoplastic deformation of stacks of woven metal wire mesh and wave processes in pore gas in a two-dimensional axisymmetric approximation. The nonlinear equations of the dynamics of two interpenetrating continua are solved numerically using a modified Godunov’s scheme. The problem of explosive loading of a multilayer shell with an internal permeable deformable layer is solved. The results of numerical solutions are compared with experimental data. The influence of the gas-permeable layer on shell deformation is determined.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):866-872
pages 866-872 views

Experimental study of the effect of a passive porous coating on disturbances in a hypersonic boundary layer 2. Effect of the porous coating location

Lukashevich S., Morozov S., Shiplyuk A.

摘要

The effect of the location of a passive porous coating on natural disturbances in a hypersonic boundary layer is studied experimentally. The experiments are performed in the flow around a sharp cone aligned at a zero angle of attack with the free-stream Mach number M = 5.8, stagnation temperature T0 = 370 ± 5 K, and unit Reynolds numbers Re1∞ = 2.6 · 106, 4.6 · 106, 6.6 · 106, and 107 m−1. The wave characteristics of the boundary layer are calculated with the use of the linear stability theory for flow parameters corresponding to experimental values. A comparison of experimental and predicted results shows that the presence of a porous coating in the region where the second mode is unstable leads to reduction of its amplitude at the measurement point, whereas the presence of a porous coating in the region of second mode stability leads to enhancement of the amplitude.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):873-878
pages 873-878 views

Flow structure in a vortex chamber

Akhmetov D., Akhmetov T.

摘要

The structure of a swirl flow in a vortex chamber is studied. Distributions of the azimuthal and axial components of velocity are obtained almost in the entire volume of the chamber. A pattern of streamlines of this flow is constructed, and the mechanism of the emergence of a reverse flow directed toward the closed end face of the chamber is identified.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):879-887
pages 879-887 views

Finite element analysis of the temperature field in laser cladding of Ni-based powders on teeth surfaces of the helical gear

Chen L., Liu S., Tao R., Liu D., Lou D., Bennett P.

摘要

The temperature field formed in the process of laser cladding of worn teeth surfaces of the gear shaft is simulated by the finite element analysis software. Isothermal lines inside the tooth are obtained. Simulated results are compared with experimental data. Recommendations are given on improvement of the cladding technology to provide a durable continuous coating.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):888-893
pages 888-893 views

Research on the skirt tail explosively formed projectile stable shaping technology

Li W., Wang X., Li W., Chen K.

摘要

The effect of the arc-cone liner configuration parameters on explosively formed projectile (EFP) flight stability is studied experimentally. The effect of the liner edge structure on the EFP formation is computed numerically. The results show that an EFP formed by a liner whose thickness is 0.046 times the charge caliber has improved flight stability and can perforate a steel armor 0.5 times the charge caliber thick in the case of large stand-off distances. A good tail skirt EFP can be formed by choosing appropriate parameters: the liner-to-charge diameter ratio in the interval 0.96–0.98, the liner edge thickness equal to 0.0020–0.0025 times the charge caliber, and the liner edge chamfer of 45–50°.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):894-899
pages 894-899 views

Computational modeling of an MHD flow of a non-Newtonian fluid over an unsteady stretching sheet with viscous dissipation effects

Tufail M., Butt A., Ali A.

摘要

An investigation has been conducted on the MHD Casson fluid and heat transfer over an unsteady stretching sheet with viscous dissipation effects. With suitable dimensionless variables, partial differential equations are reduced to ordinary differential equations, which are then solved by the homotopy analysis method. Dependences of flow characteristics on various parameters involved into the equations are obtained.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):900-907
pages 900-907 views

MHD boundary-layer flow of a non-Newtonian nanofluid past a stretching sheet with a heat source/sink

Madhu M., Kishan N.

摘要

The goal of the present paper is to examine the magnetohydrodynamic effects on the boundary layer flow of the Jeffrey fluid model for a non-Newtonian nanofluid past a stretching sheet with considering the effects of a heat source/sink. The governing partial differential equations are reduced to a set of coupled nonlinear ordinary differential equations by using suitable similarity transformations. These equations are then solved by the variational finite element method. The profiles of the velocity, temperature, and nanoparticle volume fraction are presented graphically, and the values of the Nusselt and Sherwood numbers are tabulated. The present results are compared with previously published works and are found to be in good agreement with them.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):908-915
pages 908-915 views

On a magnetohydrodynamic flow of the Casson fluid with partial slip and thermal radiation

Shehzad S., Hayat T., Alsaedi A., Meraj M.

摘要

A magnetohydrodynamic flow of the Casson fluid over a stretching surface in the presence of the slip condition, heat transfer, and thermal radiation is considered. The effects of the skin friction coefficient and local Nusselt number on flow parameters are analyzed numerically. The present results are compared with the existing limiting solution.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):916-924
pages 916-924 views

Lie symmetry analysis of a double-diffusive free convective slip flow with a convective boundary condition past a radiating vertical surface embedded in a porous medium

Afify A., Uddin M.

摘要

A numerical study of a steady two-dimensional double-diffusive free convection boundary layer flow over a vertical surface embedded in a porous medium with slip flow and convective boundary conditions, heat generation/absorption, and solar radiation effects is performed. A scaling group of transformations is used to obtain the governing boundary layer equations and the boundary conditions. The transformed equations are then solved by the fourth- and fifth-order Runge–Kutta–Fehlberg numerical method with Maple 13. The results for the velocity, temperature, and concentration profiles, as well as the skin friction coefficient, the Nusselt number, and the Sherwood number are presented and discussed.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):925-936
pages 925-936 views

On numerical modeling of capillary flow dynamics in a microchannel model by using the finite element method

Lee C., Lee C., Lin J., Liu M.

摘要

A simple microchannel model with submillimeter-scale geometries is proposed for studying capillary flows and investigating the dynamics in the channel. The finite element method incorporating surface tension and two-phase flow characteristic is applied. Velocity and pressure fields in the microchannel are presented. It is shown that the capillary-phase front in the microchannel is stirred, suffering small oscillations and retreating from the previous position before traveling again. Such a phenomenon is caused by nonlinear interaction of the capillary flow, surface tension, and boundary conditions.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):937-948
pages 937-948 views

Analysis of heat transfer over a plate in a porous medium with a convective boundary condition

Mukhopadhyay S., Mandal I.

摘要

Heat transfer characteristics of an incompressible viscous fluid past a plate embedded into a porous medium with a convective boundary condition are obtained by using the Darcy–Forchheimer–Brinkman model. The governing partial differential equations are reduced to nonlinear ordinary differential equations, and similarity solutions are obtained. The similarity equations are solved numerically. With increasing convective parameter, the surface temperature increases. The rate of heat transfer increases as the Prandtl number increases.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):949-956
pages 949-956 views

Heat enhanced by an exothermic reaction on a fully developed MHD mixed convection flow in a vertical channel

Jayabalan C., Sivagnana Prabhu K., Kandasamy R.

摘要

The problem of a fully developed MHD mixed convection flow in a vertical channel with the first-order chemical reaction is analyzed. The dimensionless governing ordinary differential equations are solved numerically by using the Maple 18 software. It is observed that dual solutions exist for both velocity and temperature.

Journal of Applied Mechanics and Technical Physics. 2016;57(5):957-962
pages 957-962 views