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A two-phase control system designed for thermally regulating the electronic equipment of the spacecraft is presented. The system comprises three capillary pumps installed in parallel, a common radiator and a radiant subcooler. Two capillary pumps are identical, while the third, smaller in volume and overall dimensions, functions as an active temperature controller. The system is equipped with measuring equipment for facilitating experimental work. [ABSTRACT FROM AUTHOR]

The constitutive equations describing the elastoplastic deformation of an isotropic material and taking into account the stress mode are validated against available experimental data. We propose a method for the approximate determination of the base functions appearing in the constitutive equations and relating the first and second invariants of the stress tensors and the linear components of finite strains. The strain components obtained by this method are compared to experimental data [ABSTRACT FROM AUTHOR]

The paper compares two approaches to determining the axisymmetric elastoplastic stress-strain state of laminated shells made of isotropic and transversely isotropic materials with different elastic moduli in tension and compression. The approaches use different nonlinear constitutive equations describing the elastic deformation of the transversally isotropic bimodulus materials. Both approaches employ the theory of deformation along paths of small curvature and the Kirchhoff-Love hypothesis for the whole laminate to describe the deformation of the isotropic materials. The problem is solved by the method of successive approximations. The solutions of specific problems obtained by the two approaches are analyzed [ABSTRACT FROM AUTHOR]

The paper presents a technique for numerical analysis of the elastoplastic stress-strain state of flexible laminated shells of revolution made of isotropic and transversely isotropic materials and subjected to axisymmetric loading and heating. The technique is based on the Kirchhoff-Love hypotheses for the whole laminate. The deformation of the isotropic materials is described using the theory of deformation along paths of small curvature. The deformation of the transversely isotropic material is described using the flow theory with isotropic hardening. The process of loading is divided into steps at each of which the stress-strain state is determined by the method of successive approximations. A numerical example is given [ABSTRACT FROM AUTHOR]

A finite-element algorithm is proposed for the analysis of the thermoviscoelastoplastic stress-strain state of bodies under complex loading (thermal and mechanical). It is assumed that an arbitrary element of the body deforms along a rectilinear or slightly curved path. The three-dimensional stress-strain state of the body’s elements is determined using the iterative method of additional strains. The technique is tested by analyzing the three-dimensional viscoelastic stress-strain state of a hollow cylinder and the thermoplastic state of a disk [ABSTRACT FROM AUTHOR]

Equations relating the components of the stress and strain tensors (constitutive equations) are formulated in terms of Euler coordinates. The equations describe the finite elastoplastic deformation of an isotropic body along paths of small curvature. It is assumed that the stress deviator is coaxial with the plastic-strain differential deviator. The relationships between the first and second invariants of the stress and strain tensors in the case of complex elastoplastic deformation of the body’s elements are determined from base tests on tubular specimens loaded along rectilinear paths for several values of the stress mode angle. Methods for specification of these relationships are proposed. The assumptions adopted to derive the constitutive equations are validated experimentally [ABSTRACT FROM AUTHOR]

A procedure for numerical investigation of nonaxisymmetric temperature fields and the elastic stress-strain state of laminated rotational bodies of cylindrically and rectilinearly orthotropic materials under nonisothermal loading is proposed. The deformation of orthotropic materials is described by the equations of anisotropic elasticity theory. The equations of state are written in the form of Hooke’s law for homogeneous materials, with additional terms which take into account the thermal deformation, changes in the mechanical properties of materials in the circumferential direction, and their dependence on temperature. A semianalytic finite-element method in combination with the method of successive approximations is used. An algorithm for numerical solution of the corresponding nonlinear boundary problem is elaborated, which is realized as a package of applied FORTRAN programs. Some numerical results are presented. [ABSTRACT FROM AUTHOR]

A technique is proposed for approximate specification of the functionals of the thermoviscoplastic equations for complex loading of isotropic materials along arbitrary plane paths. The lag in the vector and scalar properties of the material is taken into account. Instantaneous deformation and creep diagrams plotted in baseline experiments are used. The technique is used to analyze a specific deformation process. The calculated results agree well with experimental data [ABSTRACT FROM AUTHOR]

Consideration is given to the solution of a dynamic problem for a solid of revolution with an arbitrary meridional section under impulsive thermomechanical loading inducing elastoplastic strains. The theory of small elastoplastic deformations is used. The constitutive equations are linearized by the variable-parameter method. The unloading process is described by a linear law. The solution technique involves the finite-element approximation in spatial coordinates and the finite-difference representation of time derivatives. Based on the principle of linear summation, recurrent relations are derived for successive evaluation of nodal displacements by an explicit scheme in time. Solution for cylinders and disks are presented to illustrate the influence of elastoplastic deformations on wave processes [ABSTRACT FROM AUTHOR]

A technique is developed to determine the axisymmetric, geometrically nonlinear, thermoplastic stress–strain state of laminated ortotropic shells of revolution under loads that cause a meridian stress state and torsion. The technique is based on the rectilinear-element hypotheses for the whole stack of layers. The active elastoplastic deformation of an ortotropic material is described by deformation-type equations that have been derived without resort to the existence conditions for the plastic potential. The scalar functions in the constitutive equations depend on the intensity of shear strains and temperature. The problem is solved through the numerical integration of a system of differential equations. The technique is tried out in designing tubular specimens subjected to axial force and torque. As an example, the elastoplastic state of a corrugated shell is analyzed [ABSTRACT FROM AUTHOR]

The paper sets forth a method of successive approximations along loading paths. The method is used to determine the thermoelastoplastic stress–strain state of laminated shells under axisymmetric complex loading. Deformation-type constitutive equations describing loading along arbitrary plane paths are employed. A numerical example is presented [ABSTRACT FROM AUTHOR]

Based on base experiments formulated, methods are proposed to specify the scalar functional in the nonlinear equations that relate generalized stresses and finite strains in the theory of plasticity. The base experiments are conducted and the functionals are specified. It is shown that the nonlinear tensorial constitutive equations can be used to describe a nonisothermal process of deformation along a rectilinear path, which is distinct from the base ones, at high temperatures that cause creep strains [ABSTRACT FROM AUTHOR]

It is shown that the constitutive equations proposed earlier to describe the thermoviscoplastic deformation of body's elements along paths of arbitrary curvature and small torsion also describe adequately the deformation of these elements under compound nonisothermal loading along a spatial path. Use is made of the methods developed on the basis of base tests to specify the functionals appearing in the constitutive equations and accounting for the lag in the scalar and vector properties of the material. [ABSTRACT FROM AUTHOR]

The constitutive equations are derived to describe the thermoviscoplastic deformation of a solid along paths of arbitrary curvature and small torsion. Methods are developed to determine scalar functionals appearing in the constitutive equations on the basis of base experiments. The assumptions and hypotheses adopted in deriving the constitutive equations are experimentally confirmed. [ABSTRACT FROM AUTHOR]