Analysis of the transition zone in combined metal/reinforced-plastic shells

The bending stresses in the conical joint zone of cylindrical shells composed of two different materials are determined for the case of internal pressure. The effect of the length of the joint on these stresses is investigated using parameters typical of steel and glass-reinforced plastic.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 465–475, May–June, 1971.     

Calculation of contact pressures in the cable pressing of a cylindrical plastic shell subjected to a nonstationary temperature field

Conclusions The use of internal heating in the manufacture of plastic shells by the cable-pressing method produces significantly higher compressing stresses in the shell, thus improving the quality of the material.Translated from Mekhanika Polimerov, No. 2, pp. 220–224, March–April, 1977.     

Critical compressive stresses in cylindrical shells composed of orthotropic layers with different orientations

The laws of variation of the strains and critical stresses for smooth thin circular cylindrical glass-reinforced plastic shells based on ÉDT-10P resin have been experimentally investigated at different orientations of the fabric reinforcement. The results of the tests are compared with the theoretical data obtained from the relations of the theory of elasticity of an orthotropic body and orthotropic shells.N. E. Zhukovskii Central Aerohydrodynamic Institute of Production Technology and Organization, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 684–690, July–August, 1973.     

Residual stress distribution in different types of adhesion joints

The results of a photoelastic investigation of the distributions of shrinkage and temperature residual stresses in glued joints and coatings are compared. The degree of nonuniformity of the residual stress distribution over the length and thickness is determined as a function of the scale factor. It is shown that the bulk of the residual stresses in metal joints glued with K-115 epoxy adhesive are temperature stresses, which may reach 130 kgf/cm². The shrinkage and temperature residual stress distributions are similar in character.Kucherenko Central Scientific-Research Institute of Building Structures. Translated from Mekhanika Polimerov, No. 4, pp. 738–742, July–August, 1971.     

Some mechanical properties of film-reinforced plastics

Model cylindrical shells have been wound from glass and Dacron (Mylar) film strip in accordance with a technique developed by the authors. A layer of glass-reinforced plastic, oriented in the direction of the circumferential tensile stresses, was applied to the outer cylindrical surface of the shells. Certain mechanical properties of the film plastics and their ability to cooperate with the glass-reinforced plastic outer layer were investigated by subjecting the shells to internal liquid pressure. The possibility of obtaining impermeable shells, equally strong in the axial and circumferential directions, was confirmed.Bauman Moscow Higher Technical College. Translated from Mekhanika Polimerov, No. 1, pp. 135–139, January–February, 1971.     

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.     

Shrinkage stresses in bonded plexiglas structures

It is shown by means of photoelasticity that the shrinkage stresses associated with cold polymerization of the adhesive layer in bonded plexiglas structural elements seriously reduce the reliability of the structure. By suitable heat treatment it is possible to reduce the shrinkage stresses by a factor of approximately four without distorting the shape of the element and increase the permissible stresses by a factor of almost three.S. M. Kirov Ural Polytechnical Institute, Sverdlovsk. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 734–736, July–August, 1968.     

Study of the strength of plastic sandwich construction

Results are given for edge-supported sandwich panels with a honeycomb core tested in bending in two directions. The experimental data are compared with theoretical results obtained from equations proposed by the authors. It is established that in designing honeycomb panels for bending in two directions it is possible to treat the panel material as virtually isotropic in the plane of the laminations and to use the authors' equations for determining the deflections and the normal and shear stresses.Mokhanika Polimerov, Vol. 1, No. 5, pp. 45–50, 1965     

A new refined theory of anisotropic shells

A new refined theory of anisotropic thin shells is constructed with allowance for the effects associated with all the transverse strains and stresses neglected in constructing the classical theory.Institute of Mathematics and Mechanics, Academy of Sciences of the Armenian SSR, Erevan. Translated from Mekhanika Polimerov, No. 5, pp. 884–896, September–October, 1970.     

Effect of material properties on the stability of transversely isotropic shells with an elastic filler subjected to the action of mechanical loads and temperature

The effect of the low shear strength of the material (glass-reinforced plastic) on the stability of cylindrical shells with an elastic filler is investigated in relation to axial compression, external pressure, and heating. The equations of the thermoelastic problem of the theory of monotropic shells, constructed with allowance for the effect of tangential shearing stresses, are used in the calculations.Physicomechanical Institute, Academy of Sciences of the Ukrainian SSR, L'vov. L'vov Polytechnic Institute. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 903–907, September–October, 1970.     

Stress-strain state and stability of composite sandwich shells with a scaling zone between the core and facings

A finite element model is presented for analyzing the strength and stability of sandwich shells of arbitrary configuration with an adhesion failure zone between the core and one of the facings. The model is based on the assumptions that both facings are laminated Timoshenko-type composite shells, only transverse shear stresses in the core and normal stresses in the thickness direction have nonzero values, a free slip in the tangential plane in the adhesion failure zone and unilateral contact along the normal are possible, and the prebuckling state in the stability problem is linear. Biquadratic nine-node approximations for all functions and numerical integration were used. The displacements and rotation angles of the normals toward the facings as well as stresses in the core are taken as global degrees of freedom. The algebraic problem is solved using a special step-by-step procedure of determining the contact area in the scaling zone and employing unilateral constraints for some of the unknowns. Numerical examples are also given.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 5, pp. 640–652, September–October, 1993.     

Effect of the conditions of formation of glued joints on their thermophysical properties

A correlation has been experimentally established between the thermal resistance of adhesive films and the internal stresses that develop during the curing process. During cure the thermal resistance varies in parallel with the internal stresses. It is assumed that the development of thermal resistance is determined by the tension produced in the film by the development of the internal stresses.Voronezh Forest Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 754–756, July–August, 1973.     

Torsion of laminated cylindrical shells with adhesive interlayers

Based on refined equations of the Timoshenko-type shell theory, the contact stresses in torsion of a two-layer cylindrical shell with an adhesive interlayer are numerically studied. The effect of the geometric and physical-mechanical parameters of the load-carrying layers and adhesive interlayer of the shell on the distribution of the interlaminar tangential stress is analyzed. The results are presented graphically.Presented at the 10th International Conference on the Mechanics of Composite Materials (Riga, April 20–23, 1998).Pidstryhach Institute of Applied Problems of Mechanics and Mathematics, National Academy of Sciences of Ukraine, Lviv, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 4, pp. 501–506, July–August, 1998.     

Optimal position of a strut on a cylindrical shell

A solution is given for the problem of the optimal design of a rigid structure consisting of a spherical shell and two cylindrical shells linked by a strut. The volume of the structure is minimized under constraints on the maximal equivalent stresses in each of the shells and on the geometric parameters of the strut. Among the regulating parameters are the thickness of the shells, the geometric parameters of the strut, and the length of the first of the cylindrical shells. The problem is solved by the method of geometric programming.Translated from Matematicheskie Metody i Fiziko-Mekhanicheski Polya, No. 29, pp. 76–80, 1989.     

A study of glass reinforced polyethylene

The effect of dressing a fiber on the wetting of it by a polyethylene melt is studied. The interconnection between the value of the adhesive strength and the residual stresses at the boundary between the glass fiber and polymer is analyzed. The role of the residual stresses during use of the glass-reinforced material and the part played by the chemical interaction between the polyethylene and the fiber in the water-resistant composition obtained in this way is analyzed.D. I. Mendeleev Moscow Chemicotechnical Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1048–1052, November–December, 1972.     

A refined model for three-point bending of sandwich panels. 1. Deflections and bending stresses

Design formulas for the flexural characteristics of sandwich panels under three-point loading by point forces, taking into account local effects, have been derived. Transverse deformation of the normal in the modified model is deduced in terms of the difference between deflections of face layers. It is considered that the rotation of the normal depends also on shear of the filler. The deflections, local curvatures, and bending stresses, dependent on the face-layer thicknesses and transverse characteristics of the filler, are studied. The danger of initial failure caused by the local moment stresses at the central panel section is shown. Comparative estimates refining the conventional designs are established.Institute of Polymer Mechanics, Latvian Academy of Sciences, Riga LV-1006, Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 6, pp. 747–767, November–December, 1997.     

Creep of a thermoplastic cylindrical shell under axisymmetric loading

The solution of the problem of creep of an axisymmetrically loaded thermoplastic cylindrical shell is considered. The strains and stresses for the zero-moment zone and with allowance for the edge effect are predicted on the basis of Kachanov's variational method using a computer. An algorithm is constructed for polyethylene and PVC shells at various values of the load. The analysis of the results obtained is illustrated by the calculation data for individual variants of the program.Leningrad Mozhaiskii Military Engineering Academy. Translated from Mekhanika Polimerov, No. 3, pp. 512–518, May–June, 1969.     

The influence of original imperfections on the equilibrium states of physically nonlinear panels

The influence of original imperfections, curvature of the panels, and the level of growth of plastic deformations on the equilibrium states of longitudinally compressed cylindrical panels have been studied. The physical relationships were established on the basis of the theory of localized deformations. It has been found that original imperfections substantially lower the upper critical stresses in the zone of elastic and slowly growing plastic deformations, depending on the curvature parametera/R. In a zone of growing plastic deformations, the solution according to nonlinear shell theory approximates the solution according to linear shell theory, and change of curvature of the panels does not cause a sharp increase of the upper critical stress as occurs in a zone of plastic deformations.Institute for Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 345–351, March–April, 1970.     

Strain continuity equations in Timoshenko-type shell theory

The general linear continuity equations for shells for which the Timoshenko shear model is used as the kinematic relations are derived in tensor form. Particular cases of the continuity equations are considered for shells with the lines of principal curvature as coordinates and for cylindrical shells.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 105–109, January–February, 1973.     

Stability of orthotropic cylindrical shells under variable pressure

A method of determining the critical stresses is developed for elastic orthotropic cylindrical shells subjected to nonuniform pressure. It is assumed that the external pressure varies over the cross section and is constant along the length of the cylinder. A shell stability analysis is given for the case of a weakly varying load.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 5, pp. 897–902, September–October, 1970.