Synthesis of optimum cylindrical shells of reinforced plastics for an external pressure and axial compression

The synthesis of anisotropic cylindrical shells of minimum weight is considered; the initial data relate to the characteristics of the reinforcing filaments and binder. The optimum case satisfying the requirements of stability, strength, and geometrical limitations is found by the method of projective gradients.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Kaunass Polytechnic Institute. Translated from Mekhanika Polimerov, No. 2, pp. 301–309, March–April, 1972.     

Stability of cylindrical glass-reinforced plastic shells under external pressure

The stability of cylindrical glass-reinforced-plastic shells under external omnidirectional hydrostatic pressure has been the subject of an experimental investigation. The experimental data obtained are compared with calculations based on the theory of orthotropic shells.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1089–1095, 1967     

Cylindrical reinforced shells most stable under multilateral external pressure

Rational parameters are selected for reinforcing a cylindrical shell, which is externally loaded on all sides, in which the upper critical loading achieves the maximum value. Determinations are made of the appropriate region of application of the solution discovered for all elastic elements of the composition, and also indications given of the possibility of constructing other projects which in the specified concept can be considered rational.Institute of Hydrodynamics, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Mekhanika Polimerov, No. 1, pp. 75–83, January–February, 1975.     

Influence of heating on the stability of fiberglass reinforced plastic shells during axial compression

Results are described of the experimental investigation of the patterns of change of carrying capacity and deformation of smooth thin-walled round cylindrical shells made from fiberglass reinforced plastic based on phenol-formaldehyde binder, loaded by an axial compressing force in a temperature field uniform with respect to the thickness of the wall and the surface. The experimental data are compared with calculated ones obtained according to the formulae of the theory of orthotropic shells. The influence of circumferential compressing stresses arising in the junction zone of the heated wall with less heated thicker parts at the edges (ribs) on the carrying capacity of the shells is evaluated.Professor N. E. Zhukovskii Central Aerodynamics Institute, Moscow Oblast. Translated from Mekhanika Polimerov, No. 5, pp. 838–845, September–October, 1972.     

Stability loss of reinforced cylindrical shells under isotropic external pressure

Conclusions 1. Upon the loading of a composite shell having a metallic matrix the shear effects are insignificant even in the case of comparatively large volume reinforcement contents and wall thicknesses.2. The principal modulus of a material which determines the stability of a reinforced shell upon isotropic external pressure is the secant modulus in the circumferential direction.3. In the case of complex reinforcement schemes some decrease in the stability of the shell is possible, probably due to an imperfection in reinforcement technology.Institute of Solid State Physics, Academy of Sciences of the USSR, Moscow Region. Translated from Mekhanika Polimerov, No. 1, pp. 90–95, January–February, 1977.     

Plastic buckling of cylindrical shells subjected to external fluid pressure

Summary The problem considered here is that of a thin-walled circular cylindrical shell whose external surface is submitted to uniform fluid pressure. The condition under which bifurcation will occur in the shell beyond the elastic limit is examined and the true tangent modulus formula for the plastic buckling is established. Numerical results are presented for the critical pressure, covering both elastic and plastic ranges of buckling.

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Zusammenfassung Einige Betrachtungen über das Verzweigungsproblem einer dünnen Kreiszylinderschale mit homogen verteiltem Aussendruck führen zu einem exakten Ausdruck für die kritische Last im elastisch-plastischen Bereich. Verschiedene numerische Resultate für die kritische Last im elastischen sowie im plastischen Bereich werden angegeben.

     

Creep stability of glass-reinforced plastic cylindrical shells under long-term external pressure

The behavior of a glass-reinforced plastic cylindrical shell under long-term hydrostatic pressure is investigated using the geometrically nonlinear equations of Timoshenko-type shell theory, which permit transverse shear strains to be taken into account. A system of nonlinear differential equations for describing the variation of the state of the shell with time under load is obtained and solved on a BÉSM-3M computer using a program written in Algol-60 and a "Signal" translator. Values of the critical time are obtained for various load levels.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 81–85, January–February, 1970.     

Static and dynamic buckling modes of spherical shells subjected to external pressure

We investigate the possibilities for simplification of previously proposed refined linearized equations of perturbedmotion to identify, by dynamic method, the buckling mode shapes of isotropic spherical shells undergoing external hydrodynamic pressure. In the analysis of classical flexural buckling shapes of spherical shells, it is shown that preserving of nonconservative parametric terms in governing equations of formulated problem, which are related with loading of the shell with follower pressure practically does not affect the value of critical load and the resulting bucklingmode shapes in shell.     

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.     

Numerical analysis of laminated shells under in-plane axial compression

The authors of the paper present numerical stability analysis of axially compressed laminated shells. The analysis is carried out by using the commercial code NX-Nastran and authors' own program. In both cases the Equivalent Single Layer approach is adopted, in which the laminated shell is treated as an orthotropic single layer panel with the resultant stiffness calculated for the multilayered cross-section. Since the distribution of displacement in the thickness direction is assumed to be linear (First Order Shear Deformation), the shell kinematics is consistent with the Reissner-Mindlin type theory. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Behavior of glass-reinforced plastic cylindrical shells subjected to an external pressure pulse

The transient process of deformation of a cylindrical glass-reinforced plastic shell loaded with an axisymmetric external pressure pulse has been experimentally investigated. It is shown that as the amplitude of the load is monotonically increased (duration fixed), the axisymmetric motion of the shell is characterized first by linear and then nonlinear flexural oscillations.Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 327–330, March–April, 1972.     

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.     

Stability of cylindrical casings of fiberglass plastic having an elastic filler under the action of axial compression,external pressure,and twisting

The stability of orthotropic cylindrical casings containing a filler is studied under the action of axial compression, external pressure, or twisting. Analogies with plates are established for sufficiently stiff fillers. Simple formulas are obtained for calculating critical stresses which are convenient for practical application.Translated from Mekhanika Polimerov, No. 3, pp. 484–489, May–June, 1974.     

Long-time stability of orthotropic cylindrical shells under external pressure

The problem is solved using a refined theory of shells that takes shear strains into account. The shell deformations are described by means of the relations for an orthotropic material, it being assumed that creep strains develop only as a result of shear forces. The geometrically linear problem is considered. For the sake of comparison, the long-time critical load is calculated on a Minsk-22 computer using the Kirchhoff-Love and refined models. It is shown that when shears are taken into account, in certain cases the critical load may be reduced by 30%.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 315–320, March-April, 1969.     

Effect of the stiffness of the elastic core on the buckling mode and the critical load for glass-reinforced plastic cylindrical shells in axial compression

The effect of the stiffness of the core, treated as a three-dimensional elastic body, on the buckling mode and the critical load is investigated for orthotropic cylindrical shells in axial compression. Parametric equations that permit the easy determination of the critical loads are obtained together with an expression for the stiffness parameter at which the buckling mode changes. The effect on the critical load of a central opening in the core is considered.Translated from Mekhanika Polimerov, No. 5, pp. 931–939, September–October, 1971.