Experimental investigation of the stability of glass-reinforced plastic cylindrical shells subjected to long-term axial compression

The results of an experimental investigation of circular cylindrical glass-reinforced plastic shells under long-term axial compression are reported. The experimental method and the experimental apparatus are described. The initial irregularity functions and their evolution during loading and in time at various values of the compressive loads are investigated. The spread of the critical times at a given load level is studied together with the dependence of the critical time on the compressive load. The behavior of the shell after unloading and under alternating loading and unloading is considered. The correlation between the buckled shapes resulting from long-term compression and the initial irregularity functions is examined.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 710–713, July–August, 1973.     

Effect of cooling regime on the shrinkage stresses in glass-reinforced plastic cylindrical shells

Approximate stepwise cooling of the product is proposed as a means of taking into account the effect of the inelastic properties of the resin at high temperatures on the macroscopic shrinkage stresses in glass-reinforced plastic cylindrical shells.     

Dynamic stability of axisymmetrically heated glass-reinforced plastic cylindrical shells bonded to elastic cylinders

The dynamic stability of glass-reinforced plastic shells subjected to the action of a longitudinal pulsating force and an external, uniformly distributed load is examined. The shells are orthotropic, and their elastic properties are temperature-dependent and vary over the thickness of the wall. It is assumed that the elastic cylinder forms a Winkler foundation. Three boundary conditions are investigated.Moscow Institute of Chemical-Machine Building. Translated from Mekhanika Polimerov, No. 2, pp. 331–337, March–April, 1972.     

Torsional stability of a glass-reinforced plastic cylindrical shell with an elastic core

The problem of the stability of a glass-reinforced plastic cylindrical shell with an elastic core subjected to twisting moments applied to the edges of the shell is considered. As in various other studies [4–6], the glass-reinforced plastic is treated as an elastically orthotropic material. The core is treated as an isotropic elastic cylinder, whose outer surface is bonded to the shell. Expressions for the critical stresses are obtained for an infinitely long shell and a shell of finite length.Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1082–1086, November–December, 1970.     

Effect of transverse shear on the stability of an orthotropic cylindrical shell with an elastic core in axial compression

The effect of transverse shear on the stability of a composite shell in axial compression has been investigated. The core is treated as an isotropic elastic cylinder bonded to the inner surface of the shell. The effect of the tangential shearing forces between the shell and the core is taken into account.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 267–273, March–April, 1973.     

Investigation of the initial imperfections and buckling modes of glass-reinforced plastic shells under hydrostatic pressure

The results of testing the stability of glass-reinforced plastic cylindrical shells under hydrostatic pressure are examined. The initial imperfections and deflections of the shells were directly measured. It is found that during loading or in the course of time (under load) the shape of the initial imperfections is transformed. An algorithm (see [11]) based on the approximation of the experimental deflection function by a Fourier series is used to establish the characteristic coefficients of the series important in connection with the elastic loss of stability and progressive buckling of the shell.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1057–1063, November–December, 1971.     

Optimal winding of filament-wound reinforced plastic shells designed to resist buckling under external pressure or axial compression

The optimal method of winding the reinforcement of thin cylindrical shells subjected to external pressure or axial loading is investigated. Various types of winding — normal, simple oblique, crossed, and isotropic — are considered. An approximate formula is obtained for the critical external pressure. This formula is used to analyze the possibility of raising the critical load by adopting oblique winding. In the case of axial compression different buckling modes are examined and the optimal winding determined.Central Scientific-Research Institute of Machine Building, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 864–875, September–October, 1968.     

Dynamic stability of cylindrical orthotropic shells with an elastic core under a longitudinal periodic load

The dynamic instability of a cylindrical orthotropic shell with an elastic core subjected to a longitudinal periodic load is considered. Equations are obtained for determining the regions of dynamic instability for different core models.     

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.     

Buckling and vibration of the two-dimensional quasicrystal cylindrical shells under axial compression

In this paper, the buckling and the free vibration of the quasicrystal cylindrical shells under axial compression are investigated. Three quasi-periodicity cases of quasicrystal cylindrical shells are considered. The first-order shear displacement theory of the cylindrical shells is utilized to obtain the equations of motion and the boundary conditions. Numerical results for simply supported cylindrical shells at the two ends are calculated. The effects of the geometry, in-plane phonon and phason loads, and half-wave number of the quasicrystal cylindrical shells on both the buckling loads and the frequency are demonstrated.     

Method of calculating the macroscopic shrinkage stresses in cylindrical glass-reinforced plastic shells with allowance for certain technological factors

The effect of certain technological factors, in particular, the thermophysical characteristics of the mandrel material, the degree of anisotropy of the fabricated article, and the inelastic properties of the matrix, on the magnitude and distribution of the macroscopic shrinkage stresses is examined in the case of cylindrical glass-reinforced plastic (GRP) shells.     

Effect of the two-way reinforcing system on the load-carrying capacity of glass-reinforced plastic shells

The load-carrying capacity of thin cylindrical glass-reinforced plastic shells loaded by axial compression and external pressure has been investigated in relation to the characteristics of the two-way reinforcing system. The critical loads are expressed in terms of the characteristics of a parallel-reinforced layer with a coefficient that takes into account the reinforcing system and the shape of the cross section. The relations among the reinforcing layers optimal for the load-carrying capacity are determined and it is shown that independent two-way reinforcing substantially improves the load-carrying capacity of solid shells and shells with a nonload-bearing core.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 1052–1058, November–December, 1969.     

Effect of the end conditions on the critical loads for filament-wound glass-reinforced plastic columns

The behavior of glass-reinforced plastic columns with various end conditions has been experimentally investigated. The cross-wound columns had a length to mean diameter ratio of 18–20. Four types of support with different degrees of restraint on end rotation ranging from almost free ends to fixed ends were employed. The possibilities of increasing the critical loads by manipulating the boundary conditions are estimated. Numerical estimates are obtained for the various methods of support. Random imperfections and the number of loadings were not found to have any effect on the critical loads. It is shown that the use of Southwell's method makes it possible to estimate the critical loads for columns with different end conditions from the subcritical loading data.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 54–62, January–February, 1976.     

Effect of a local load on an orthotropic glass-reinforced plastic shell

The deformation of a layered orthotropic cylindrical shell under a local normal load is investigated on the basis of equations that do not depend on the hypothesis of straight normals. The solutions of the analogous classical problems were analyzed in [3]; a solution based on equations that take transverse shear strains approximately into account was proposed in [4]. The high degree of variability of the state of stress created by local loads indicates that it is quite important to take transverse shear strains rigorously into account in problems of this class. An attempt is made to estimate the error introduced by the hypothesis of straight normals and to calculate the load leading to debonding of the shell.S. Ordzhonikidze Moscow Aviation Institute. Translated from Mekhanika Polimerov, No. 1, pp. 95–101, January–February, 1970.