Deformation of a glass-reinforced plastic cylindrical shell encased in a thick-walled elastic cylinder

A solution is given for the axisymmetric problem of the deformation of an orthotropic glass-reinforced plastic shell of finite length encased in a soft transversely isotropic cylinder under internal pressure.Moscow Institute of Heat Engineering. Translated from Mekhanika Polimerov, No. 1, pp. 164–168, January–February, 1973.     

Bending of a cantilevered glass-reinforced plastic cylindrical shell weakened by a circular opening

The stress concentration is investigated in the neighborhood of a circular opening in a cantilevered glass-reinforced plastic cylindrical shell with a concentrated load at the free end. The problem is solved by the Bubnov method using a Ural-2 computer. The theoretical results have been checked experimentally on glass-reinforced plastic shells.All-Union Correspondence Polytechnic Institute, Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 152–157, January–February, 1970.     

Region of linearity of the deformation properties of contact-molded glass-reinforced plastic

A study was made of the creep and recovery of contact-molded glass-reinforced plastic in different directions in the plane of the sheet in uniaxial tension. On the basis of experimental data, the region of linearity of the deformation properties of the material under investigation was established. The influence functions in the relations of the theory of viscoelasticity were taken in the form proposed by Bronskii. The dependence of the parameters which determine these functions on direction was investigated. It is shown that, in practice, this dependence is inherent in only one of the parameters, and a relationship which is in satisfactory agreement with the experimental results is proposed to describe it.Moscow Institute of Chemical Machine Building. Scientific-Research Institute for Mechanics, M. V. Lomonosov State University, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 404–410, May–June, 1970.     

Plane-stress creep of a glass-reinforced plastic

The creep behavior of an orthotropic glass-reinforced plastic based on Polimal'-109 resin and 19-S4 glass fabric is described. A special device for testing tubular specimens in plane-stress creep has been designed. The loading conditions include combined torsion and tension, internal pressure, and loading along the principal directions of anisotropy. Constitutive equations describing creep and recovery are proposed for the two-dimensional case.Warsaw. Translated from Mekhanika Polimerov, No. 3, pp. 398–410, May–June, 1971.     

Carrying capacity and deformation properties of glass-reinforced plastic pipes of various construction

Glass-reinforced plastic pipe under internal hydrostatic pressure starts to sweat at loads lower than the mechanical strength of the material. It is established that the life of such pipes is well described by an exponential law. The leakage mechanism is mainly controlled by the deformation properties of the reinforcement and resin. The period of reliable service can be estimated from the time of development of the strain corresponding to the end of the phase of steady-state creep. It is shown that for pipe made with cross-wound glass rovings, the winding angle and the number of roving ends have a considerable influence on the creep and life.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1082–1088, 1967     

Mechanical properties of a hollow-fiber glass-reinforced plastic

The strength and elastic properties of a hollow-fiber glass-reinforced plastic are investigated together with the effect of temperature, and long-time and cyclic loading on its mechanical characteristics. The instantaneous moduli of elasticity and the creep kernel parameters are obtained on the basis of the creep diagrams.Translated from Mekhanika Polimerov, No. 2, pp. 341–345, March–April, 1971.     

Optimal reinforcement of a glass-reinforced plastic plate

Relations are derived for the optimal arrangement of the reinforcement in a rectangular glass-reinforced plastic plate supported at the edges and stressed in uniaxial compression by a short-term or long-term, uniformly distributed load. (The optimal arrangement is understood to be that which maximizes the critical load.)All-Union Scientific-Research Institute of Railroad Transport, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 741–744, July–August, 1969.     

Experimental determination of the concentration of stresses and strains around a circular hole in a glass-reinforced plastic specimen

The results of experimental studies on the concentration of stresses and strains at a circular hole in a glass-reinforced plastic specimen, involving the use of the photoelastic coating method, are given. The effects of the anisotropy of the material, of ratio of the hole diameter to the width of the model, and of the load level on the magnitude of the stress and strain concentration factor are indicated.Translated from Mekhanika Polimerov, No. 1, pp. 159–163, January–February, 1972.     

Stability of glass-reinforced plastic columns

The stability of circular columns of unidirectional glass-reinforced plastic (EF-32-301) is investigated for two types of end conditions: hinged at both ends and one end hinged, the other fixed. The experimental data are compared with theory [1]. A relationship is established between the change in reduced length and the shear parameter.Institute of Hydrodynamics, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 906–910, September–October, 1968.     

Transient creep of glass-reinforced plastic

Short-time (up to 30 min) creep tests on SVAM glass-fiber orthotropic material at 20°C have shown that it is subject to creep even at room temperature. At the same time, the behavior of this material in creep is observed to be markedly anisotropic.Mekhanika Polimerov, Vol. 1, No. 2, pp. 47–54, 1965     

Fracture of a glass-reinforced plastic in cyclic tension-compression

Uniaxial tension-compression tests have revealed the existence of a correlation between the static and cyclic deformation characteristics of a glass-reinforced plastic. The possibility of calculating the cyclic lifetime from the static test data using Bailey's rule and Zhurkov's equation for the time dependence of the strength has been investigated. A method of allowing for the particular characteristics of the fatigue fracture of a reinforced material, based on the correlation between the static and cyclic deformation, is proposed and is found to lead to a considerable improvement in the convergence of the theoretical and actual cyclic lifetimes.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 654–662, July–August, 1971.     

Elastoplastic stability of glass-reinforced plastic plates with a central metal layer

The problem of the stability of a three-layer plate with a central plastic layer of metal sandwiched between elastic glass-reinforced plastic outer layers is considered. The presence of a metal layer restrains the development of creep strains in the glass-reinforced plastic and makes it possible to neglect the viscous strain components. The general equations of the problem are obtained, and the approximate Il'yushin formulation [1] is considered. An example is presented for a rectangular plate in pure shear. It is shown that the elastic anisotropic layers play the part of a load-relieving system for the central plastic layer [3], which results in an increase in the over-all critical load for the layered plate.Kalinin Polytechnic Institute. Translated from Mekhanika Polimerov, No. 5, pp. 909–915, September–October, 1969.     

Bending of prestressed glass-reinforced plastic beams

Initial waviness of the fibers and prestressing are investigated in relation to their effect on flexural stiffness and strength for beams with low shear strength. It is shown that prestressing the reinforcement increases the flexural stiffness but at the same time adds to the shear correction as a result of an increase in the modulus of elasticity E_x in the direction of reinforcement and the insensitivity of the shear modulus G_xz to prestress. It is established that prestressing increases the shear strength and the degree of anisotropy . Materials of two types are investigated: unidirectional (AG-4S) and cloth-reinforced (SKT-11).Mekhanika Polimerov, Vol. 3, No. 5, pp. 888–893, 1967     

Dynamic stability of glass-reinforced plastic shells

The problem of the dynamic stability of circular-cylindrical glass-reinforced plastic shells subjected to external transverse pressure is examined in the nonlinear formulation. After the Lagrange equations have been constructed, the problem reduces to the integration of a system of ordinary differential equations with aperiodic coefficients. The integration has been carried out numerically on a computer for various loading rates and shell parameters. Analogous problems for isotropic metal shells were examined in [1–4]. A review of the subject may be found in [5].Mekhanika Polimerov, Vol. 4, No. 1, pp. 109–115, 1968     

Investigation of the extremal directions in a glass-reinforced plastic

The extremal directions in an orthotropic material are investigated on the basis of six experimentally determined values of the investigated characteristic in the three planes of symmetry of the material.Translated from Mekhanika Polimerov, No. 4, pp. 742–745, July–August, 1971.     

Stability of cylindrical glass-reinforced plastic shells

The stability of cylindrical shells in axial compression has been experimentally investigated. The glass-reinforced plastic shells were fabricated in various ways: by winding glass strand, from glass cloth, and by a combination of the first two methods. The buckling mode and critical load were determined as functions of the ratio of shell radius to shell thickness. A statistical analysis of the test data leads to a formula with an empirical coefficient for use in practical stability calculations.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 5, pp. 886–891, September–October, 1969.     

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     

Impact of a massive body against a glass-reinforced plastic beam

The behavior of glass-reinforced plastic beams under the impact of a massive body is examined. The contact and wave processes associated with dynamic bending have been experimentally investigated. All the experiments are compared with a numerical solution of the Timoshenko equation.