Determination of the residual stresses in wound glass-reinforced plastic rings

The stresses that develop during winding in wound glass-reinforced plastic rings change during polymerization, when the modulus of elasticity in the radial direction is reduced by heating. Further changes occur in connection with cooling and removal from the mandrel. The theoretical relations obtained for determining these stresses are found to be confirmed by experiment.Bauman Moscow Higher Technical College. Translated from Mekhanika Polimerov, No. 5, pp. 892–898, September–October, 1969.     

Investigation of the temperature residual stresses and strains in thick-walled wound reinforced plastic products

The kinetics of the temperature residual stresses and strains in thick-walled reinforced-plastic cylinders and rings have been experimentally investigated employing a special procedure for continuously monitoring the internal strains and stresses in the various zones of the semifinished product during the heat treatment stage. The effect of the resin polymerization (polycondensation) temperature and the mandrel material on the magnitude and distribution of the temperature stresses is considered. The total residual stresses have been determined by a nondestructive strain-gauge method with differentiation of the components.Translated from Mekhanika Polimerov, No. 6, pp. 1040–1046, November–December, 1971.     

Effect of climatic loading on the residual stresses and carrying capacity of thick-walled glass-reinforced plastic rings

The effect of climatic loading on the carrying capacity of thick-walled glass-reinforced plastic rings with different residual stress levels has been experimentally investigated. It is established that the rings with the greater residual stress level have a lower maximum breaking load. The carrying capacity of the rings is reduced after simulated aging. This effect is shown to be more sharply expressed in the experiments in which the rings were subjected to dynamic loading.Translated from Mekhanika Polimerov, No. 6, pp. 1132–1134, November–December, 1971.     

Polypropylene reinforced with aramid and glass fibers

The effect of the chemical nature of the aramid fibers Phenylone, Terlon, Armos, and SVM on the mechanical, thermophysical, and antifriction properties of reinforced polypropylene was investigated. It was found that the composite filled with SVM fibers based on a stiff-chain polymer has high tensile strength and bending modulus. Reinforcement of polypropylene with Phenylone stiff-chain fibers produces a composite with a high impact viscosity. Organoplastics based on polypropylene and aramid fibers have a low density and friction coefficient and high durability. Reinforcement of polypropylene with aramid (SVM) and glass fibers increases the technological properties of the composites. The glass-filled organoplastics developed can be used in instrument making, radio engineering, and machine building as antifriction and construction materials.Ukrainian State Chemical Technological University, Dnepropetrovsk, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 106–110, January–February, 1996.     

Initial stresses in reinforced and filled polymers

The methods of the statistical theory of elasticity are used to calculate the average stresses in the components of uniaxially reinforced and randomly filled polymers arising in the process of fabricating the material as a result of the different linear expansion coefficients of the components and chemical shrinkage of the resin. Expressions are also obtained for the macroscopic characteristics of the media — moduli of elasticity, linear expansion coefficients, and shrinkage coefficients. The results are compared with experimental data and with the results of computations based on the equations proposed by other authors. The relations obtained for the dependence of the stresses in the components on their properties offer a satisfactory explanation for the experimentally established positive correlation between the shrinkage and the compressive strength of a composite based on furan resin.Gomel' State University. Kirov Urals Polytechnic Institute, Sverdlovsk. Translated from Mekhanika Polimerov, No. 1, pp. 90–96, January–February, 1973.     

Strength of glass-reinforced plastic rings loaded with internal pressure

The relation between the internal bursting pressure and the thickness of rings made of unidirectional glass-reinforced plastic has been experimentally investigated. It is shown that the carrying capacity of the rings is limited owing to the low strength of the glass-reinforced plastic in compression perpendicular to the fibers.Mekhanika Polimerov, Vol. 4, No. 1, pp. 131–135, 1968     

Theory of thermostructural stresses in reinforced plastics

A method is proposed for determining the mean values of the initial thermostructural stresses in reinforcement and matrix resulting from the uniform cooling of a two-component unloaded elastic body from the natural state (resin hardening temeprature) to the working temperature (external loading).V. A. Steklov Mathematical Institute, Sverdlovsk Branch, Academy of Sciences of the USSR. S. M. Kirov Ural Polytechnic Institute, Sverdlovsk. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 822–828, September–October, 1968.     

Laminate structures in plastic composite materials with rigid layers

A variational model for composite materials with rigid horizontal layers is introduced within the framework of geometrically nonlinear single-slip plasticity. Considering the orientation of the slip system, we discuss the effective material response in the case of vanishing layer thickness and give explicit examples of possible macroscopic deformations which are realized by simple laminate constructions. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural stresses in composites reinforced with a system of anisotropic fibers

The effect of the anisotropy of the mechanical and thermophysical characteristics of the reinforcement on the temperature stresses in unidirectional composites has been investigated. The stresses near fibers forming a regular structure in the transverse plane are estimated as a function of the thermoelastic properties of the components and the structure parameters.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 728–731, July–August, 1974.     

Residual stresses in a closed cylindrical shell with a longitudinal crack

We study the influence of the residual stresses on the size and character of the variations in the strain intensity and moment intensity coefficients in a closed cylindrical shell welded together from two parts and under the action of axisymmetric loads. We perform a numerical analysis in the case when the shell with residual stresses is acted on by internal pressure.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 27, 1988, pp. 40–45.     

Stability of glass-reinforced plastic shells with allowance for shear stresses

The stability of a cylindrical glass-reinforced plastic shell subjected to external pressure is considered in the geometrically nonlinear formulation with allowance for initial irregularities. The refined shell theory [6, 7], which enables transverse shear strains to be taken into account, is employed. A general algorithm of the solution has been written in ALGOL-60. A numerical solution of the problem has been obtained on a BÉSM-3M computer. Critical loads have been determined over a wide range of variation of the geometrical and physical parameters of the shell. It is established that the difference between the results of the classical and refined theories depends on the thickness, length, and physical parameters of the shell. The classical theory is asymptotically exact as the thickness of the shell tends to zero or the interlaminar shear modulus tends to infinity.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 857–862, September–October, 1969.     

Flexure of viscoelastic plate with holes reinforced by rigid rings

The problem of the flexure of an Isotropic viscoelastic plate with three unequal circular holes reinforced by rigid rings is solved. The influence of the viscoelastic properties of the material on the stress state of the plate as a function of the distance between the holes and their radii is investigated.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 18, pp. 56–58, 1987.     

Some features of the unwinding of glass-reinforced plastic rings

The reasons for the nonhomogeneity of the material of wound glass-reinforced plastic tubes are discussed. Formulas are given for constructing the shrinkage or temperature stress diagrams for nonhomogeneous tubes by the unwinding method.S. M. Kirov Ural Polytechnic Institute, Sverdlovsk. Translated from Mekhanika Polimerov, No. 6, pp. 1076–1081, November–December, 1973.