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We present analytic relations based on the Voigt–Reiss system of hypotheses and a refined model (based on the energy approach) for the evaluation of the effective characteristics of energy dissipation in layered composites, which enable us to obtain their reliable values. The model developed on the basis of the energy approach is based on the finite-element modeling of a representative elementary volume of the composite and on equating the energy of its cyclic deformation to the energy of a quasihomogeneous volume of the material. We compare the obtained dependences of specific dissipated energy on the volume fractions of carbon and glass fibers in the epoxy matrix with the available experimental data. [ABSTRACT FROM AUTHOR]

We study the problem of contact between two elastic bodies one of which has a discontinuous thin elastic coating in the form of a Timoshenko-type shell and propose a Robin-type domain decomposition algorithm for the solution of variational equations of this problem. The proposed algorithm is used for the investigation of contact interactions between two rectangular elastic bodies with discontinuous coatings. We analyze the dependences of the surface and equivalent stresses on the height and stiffness of the coating. The results obtained for simulated coatings by using the theory of Timoshenko-type shells and the classical theory of elasticity are compared. [ABSTRACT FROM AUTHOR]

We propose new methods for the determination of the thermal stressed state of viscoelastic bodies made of functionally graded materials subjected to annealing. We develop a numerical algorithm for the solution of the corresponding problem and realize it for the problems of heat conduction and thermoviscoelasticity. The thermal stressed state of a hollow cylinder is determined according to the given conditions of annealing. The variations of its temperature and stressed state are illustrated. [ABSTRACT FROM AUTHOR]

We develop a finite-element three-dimensional model of a Bridgman specimen with an aim to investigate its elastoplastic deformation in tension. The distribution of stresses in the cross section of the working part of the specimen for a wide range of loads is determined. It is shown that stresses acting at the center of the specimen in the stage of elastic deformation are lower than the stresses on its surface and, on the contrary, higher than the stresses in the stage of elastoplastic deformation. For a specimen made of 40Kh steel, we find a tensile force for which the normal stresses formed in its cross-section are uniform. [ABSTRACT FROM AUTHOR]

We propose a procedure for the determination of the stress-strain state of exploited metals in gaseous hydrogen at temperature varying as a function of time. In this case, we use the principle of virtual work adapted for the quasistatic equilibrium equations with step-by-step formulation in time. The increments of displacements, hydrogen concentration, temperature, strains, and stresses for a certain small time interval are determined by using the finite-element method. To check the proposed methods, we analyze the stress-strain state of a solid finite cylinder in the atmosphere of hydrogen at temperature varying as a function of time. We consider the cases where the cylinder is unrestrained or restrained at one of its ends. [ABSTRACT FROM AUTHOR]

We propose a procedure of control over the speed of response of thermal conditions in the case of thermal loading of the bodies of revolution made of functionally graded materials. The construction of solutions of the analyzed problems is based on numerical methods. To solve direct problems, we use the method of weighed residuals and the finite-element method. The solution of the posed extreme problem is based on the principle of step-by-step parametric optimization. [ABSTRACT FROM AUTHOR]

We develop a basic element of the procedure of construction of the near-threshold part of the diagram of fatigue fracture for metallic materials under the conditions of transverse shear. It is proposed to use a square sample with edge cut and a force scheme of its cyclic loading. We determine the strain-stress state of a square plate with edge crack (regarded as a prototype of the proposed specimen) under the conditions of transverse shear by two independent methods (finite-element method and the method of singular integral equations). The stress intensity factor KII is determined for a broad interval of relative crack lengths with regard for the smooth contact of the crack faces and the presence of friction between the faces. [ABSTRACT FROM AUTHOR]

We analyze the main types of defects appearing near the sites of concentration of mechanical stresses in the material of tires of the wheels of electric locomotives. We study the distribution of stresses near the areas of potential appearance of fatigue defects in the tire in the course of its setting on the wheel center by the finite element method and discuss the obtained results. [ABSTRACT FROM AUTHOR]

We compare the distributions of strains in the process zone of cross-shaped specimens under biaxial loading obtained by the methods of finite-element analysis and digital-image correlation. It is shown that the use of true stress-strain curve in the algorithm of evaluation by the finite-element method significantly improves the accuracy of simulation. The influence of biaxial loading on the local distribution of strains is analyzed. We establish good agreement between the computed and experimental results of evaluation of the local strains near the crack tip. [ABSTRACT FROM AUTHOR]

We propose a numerical model of the stress-strain state of a plane element of an elastic inhomogeneous medium with long elliptic and rectangular inclusions based on the use of the standard ANSYS finite-element package. The mutual influence of inclusions is investigated depending on their orientation, shapes, sizes, and stiffnesses. We determine the safest possible versions of their mutual location. [ABSTRACT FROM AUTHOR]

We propose an algorithm and programs for the solution of the three-dimensional problem of hydrogen diffusion. Some numerical solutions of this problem and the problem of heat conduction in the three dimensional statement are verified by analyzing test problems whose analytic solutions are known. The dependence of the relative error on the density of elements of the grid and time intervals is constructed by using the finite-element method. [ABSTRACT FROM AUTHOR]

We propose an algorithm for the solution of the problem of heat conduction and hydrogen diffusion with variable coefficients of diffusion and solubility for structurally inhomogeneous materials. As an example, we test the algorithm by solving the problem for bimetallic cylindrical specimens used, according to the ASTM G146-01 standard, for the investigation of the hydrogen resistance of bimetallic joints. We determine the distribution of hydrogen concentration in cylindrical specimens with weld overlay obtained as a result of cooling at different rates after high-temperature hydrogenation. It is shown that, in the fusion zone (on the side of the coating), we observe the formation of the zones of superequilibrium supersaturation with hydrogen, which may result in the exfoliation of the weld overlay from the base metal. [ABSTRACT FROM AUTHOR]

By the method of superposition of stressed states, we deduce a formula for the stress intensity factor K under the conditions of transverse shear of an I-beam specimen. The comparison of the results of calculations with the theoretical data obtained earlier by the finite-element method reveals their satisfactory convergence within a broad range of relative crack lengths. [ABSTRACT FROM AUTHOR]

We determine the stress-strain states near technological cracklike faulty fusions in cell elements and deduce the relation for the stress intensity factor K near a cracklike faulty fusion and determine its critical length. It is shown that the faulty fusions with lengths not greater than a half thickness of the wall do not affect the strength of cellular products. [ABSTRACT FROM AUTHOR]

We propose a new approach to the investigation of the thermomechanical states in layered plastically deformed heat-sensitive bodies of any geometric shape with arbitrary orientation of the interfaces between the layers. The proposed approach is based on the formulation of the nonstationary problem of heat conduction, problem of the theory of plastic nonisothermal flow, computational schemes of the finite-element method, and the corresponding software. We also study the thermomechanical behavior of a two-layer sphere under the conditions of rapid cooling from its initial uniform temperature. [ABSTRACT FROM AUTHOR]

We propose the design of a specimen for the investigation of the fatigue fracture of steels under transverse shear. A formula for the determination of the stress intensity factor with regard for the friction of crack lips is obtained with the use of the finite-element method. The methods aimed at the construction of the kinetic diagrams of fatigue fracture under the conditions of transverse shear are developed and tested on specimens of 65G structural steel. We plot the kinetic diagram of fatigue fracture and approximate its middle segment by a linear dependence in the established parameters. [ABSTRACT FROM AUTHOR]

We study the domain decomposition methods for the numerical solution of the problems of frictionless unilateral contact of many elastic bodies of finite sizes. By using the finite-element approximations, we solve the problems of the unilateral contact of three elastic bodies compressed by rigid plates and the contact of three fixed bodies one of which is subjected to the action of an external load. The distributions of normal contact and equivalent stresses in the bodies are analyzed. [ABSTRACT FROM AUTHOR]

We compare the values of temperature in a disk-pad-caliper tribosystem obtained by using two approaches: numerical (based on the finite-element method) and analytic obtained as the solution of the boundary-value problem of heat conduction for a half space (disk) sliding with uniform deceleration along the surface of a plane-parallel layer (pad) applied to the surface of a semiinfinite foundation (caliper). We also compare the maximum temperatures formed on the pad-disk contact surface with the well-known experimental data. [ABSTRACT FROM AUTHOR]

The parameters of signals of magnetoelastic acoustic emission are used to evaluate the influence of hydrogen on the changes in the power of Barkhausen jumps in ferromagnets. We tested two different types of materials: nickel and steel. The hydrogen content in the bulk of the specimens is computed by the finite-element method by using equations obtained from the Fick laws. It is shown that the influence of hydrogenation on the parameters of signals of magnetoelastic acoustic emission and, hence, on the power of Barkhausen jumps caused by the external magnetic field is different for different materials. [ABSTRACT FROM AUTHOR]