Contact problems for beams and plates with low shear stiffness

The low shear stiffness and strength of unidirectionally reinforced plates and beams predetermines the choice of calculation model in specific problems [4]. The contact problem is considered for a glass-reinforced plastic plate resting on a Winkler foundation; the deformation properties of the plate are described by the equations of an orthotropic material; the investigation is based on generalized applied theories of the Timoshenko and Ambartsumyan types [5–8], which permit the high shear compliance of thin-walled structures to be taken into account.L'vov Polytechnic Institute; Ivan Franko Institute of Petroleum and Gas. Translated from Mekhanika Polimerov, No. 4, pp. 715–720, July–August, 1970.     

Viscoelastic characteristics of the interaction between structures and soils

The shear coefficients of a body relative to the soil and the shear creep and relaxation kernels are determined from the data of creep and relaxation tests.Urazbaev Institute of Mechanics and Earthquake Resistance of Structures, Academy of Sciences of the SSR, Tashkent. Translated from Mekhanika Polimerov, No. 2, pp. 207–211, March–April, 1973.     

Stability of transversally isotropic shells coupled with an elastic foundation

The stability of shells coupled with an elastic Winkler foundation is investigated. It is assumed that the shell is made of a material (glass-reinforced plastic) with low resistance to shear, as a result of which generalized theories that take transverse shear strains into account [1–4] must be used in the stability calculations. The solution obtained is compared with the corresponding solution obtained on the basis of the classical Kirchhoff-Love theory [8].Lvov Polytechnic Institute. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 669–673, July–August, 1969.     

Mechanical characteristics of oriented glass-reinforced plastics in shear

The mechanical characteristics of oriented glass-reinforced plastics stressed in shear are considered. Various methods of determining them are compared. The dispersion of the shear strength is characterized and the possibility of glass-reinforced plastics elements failing as a result of low interlaminar shear strength is discussed.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1008–1013, November–December, 1969.     

Variation of the deformation resistance of phenol-formaldehyde thermosets during cure

The dependence of the viscosity of phenol-formaldehyde thermosets on the previous thermal history has been investigated at a fixed shear rate.Moscow Institute of Chemical Machine Building. Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 619–623, July–August, 1971.     

Anisotropy of the mechanical properties of cross-linked poly(n-butyl methacrylate)

Mechanical properties of cross-linked poly(n-butyl methacrylate) synthesized under shear stress are reviewed. The effect of shear stress rate and of the cross-linking agent concentration on the resulting polymer properties was demonstrated.Kiev Branch, All-Union Scientific-Research Institute of Complex Polygraphy Problems in Special Types of Printing. Institute of the Chemistry of High-Molecular-Weight Compounds, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 1, pp. 150–152, January–February, 1972.     

Relation between the shear and longitudinal viscosity coefficients for concentrated polymer solutions

A relation between the shear and longitudinal viscosity coefficients is obtained on the basis of the theory of flow of polymeric systems in the single relaxation time approximation. A comparison of the shear and longitudinal viscosity coefficients for polymer melts and solutions shows that the relation obtained is valid over a broad stress region.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Scientific-Research Institute of Synthetic Fibers, Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 124–131, January–February, 1973.     

Effect of fiber tension on the unwinding resistance of hardening layers of glass-reinforced plastic

The shear fracture toughness characteristics of glass-reinforced plastics used for strengthening metal pressure vessels have been determined by testing metal-GRP rings. The shear fracture toughness characteristics are statistically estimated for a unidirectional GRP as a function of the winding tension.K. É. Tsiolkovskii Moscow Aviation Engineering Institute. Translated from Mekhanika Polimerov, No. 5, pp. 935–938, September–October, 1975.     

Periodic shear deformation of a curing epoxy composition

The curing of an epoxy resin with amines is investigated in relation to the changes in the viscoelastic shear characteristics. The effect of the shear deformation amplitude on the curing kinetics is considered.Presented at the Symposium on Polymer Rheology, Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow, May, 1970.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 301–306, March–April, 1971.     

Experimental study of the effect of the technological factor of rolling-in (packing) on the physicomechanical properties of glass plastic

Conclusions 1. The rolling-in (packing) of wound glass-plastic objects is a favorable technological factor, improving the homogeneity of the material, increasing the elastic and strength characteristics of the glass plastic, and reducing the thermal expansion coefficients and macroscopic residual stresses due to the thermal shrinkage of the objects.2. However, extremely large packing forces may reduce certain of the mechanical characteristics of the material, chiefly the strength and modulus relating to interlayer shear.Moscow Power Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1043–1047, November–December, 1976.     

Thixotropy of filled-polyethylene melts subjected to periodic shear deformation

As a result of the action of periodic finite-amplitude shear deformations filled high-pressure polyethylene melts exhibit thixotropic properties. The effect of the previous deformation history on the frequency dependence of the complex dynamic shear modulus is investigated.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR Riga. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 927–931, September–October, 1968.     

Viscosity of melts obtained from polymers with a wide spread of particle size

By comparing existing relationships between the maximum viscosity and the molecular weight and between the effective viscosity and the shear velocity, the effect of the molecular-weight distribution of linear polymers on the shear velocity is analyzed.Scientific-Industrial Combine Plastopolimer. Scientific-Research Institute of Polymerized Plastics, Leningrad. Translated from Mekhanika Polimerov, No. 4, pp. 753–756, July–August, 1972.     

Analysis of certain methods of determining shear moduli 1. Testing composites uniform over the thickness

Four methods of determining shear moduli on flat specimens are discussed. For each method the effect of the geometric parameters and the load range on the values of the shear moduli determined is estimated. Experimental values of the shear moduli obtained by each of these methods for the same materials are compared with the calculated values.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 133–140, January–February, 1976.     

Periodic deformation and viscous flow of polymer melts and solutions (communication 1)

The principles of the theory of thixotropy are formulated. The basic relations are obtained for cases of periodic vibration superimposed on shear flow. The effect of stationary shear flow on the linear dynamic characteristics of an elastic liquid is investigated. The calculated values are compared with the experimental data.Institute of Problems of Mechanics, Academy of Sciences of the USSR, Moscow. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 519–527, May–June, 1969.     

Effect of the sign of the shear stresses on the shear strength of reinforced plastics

The effect of the sign of the shear stresses on the shear strength has been investigated for a glass-reinforced plastic of the SVAM type with various ratios of the longitudinal and transverse reinforcement in shear in the plane of reinforcement in axes turned through 45° relative to the direction of reinforcement. More than 80 tubularspecimens were tested. The shear strengths T ₄₅ ⁺ and T ₄₅ ^– corresponding to shear stresses of different signs can be found from uniaxial tests in tension and compression in the direction of the reinforcement.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 262–268, March–April, 1971.     

Resolvents of the theory of orthotropic shells with low shear stiffness in force-moments and stress functions

The problem of the theory of orthotropic layered shells with low shear stiffness is reformulated in force-moments and stress functions on the basis of new strain continuity relations constructed with allowance for transverse shears.Physicomechanical Institute, Academy of Sciences of the Ukrainian SSR, L'vov. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 950–952, September–October, 1970.     

Rheological characteristics of a low-molecular branched polyethylene melt near the melting point

Data are presented on the rheological characteristics of low-density polyethylene with near-critical molecular weight at 110°C. A comparison of the shear rate dependence of the viscosity in repeat measurements indicates that the material has a kinetic memory for isothermal, shear flow-initiated crystallization from the melt.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga; Plastpolimer Research and Production Association, Leningrad. Translated from Mekhanika Polimerov, No. 6, pp. 1129–1132, November–December, 1973.     

Some problems of the theory and analysis of anisotropic plates and shells with low shear stiffness

Certain problems associated with the theory and analysis of plates and shells made of materials with low shear stiffness are discussed.Physicomechanical Institute, Academy of Sciences of the Ukrainian SSR, L'vov. Translated from Mekhanika Polimerov, No. 4, pp. 693–714, July–August, 1970.     

Dynamic bending of plates with low shear strength

The dynamic problem of the natural vibrations of glass-reinforced plastic plates with low shear strength is examined. The calculations are based on the Timoshenko model (allowance for shear strains and rotational inertia). It is shown that disregarding effects associated with the large shear compliance of glass-reinforced plastic plates leads to appreciable errors in determining the dynamic characteristics.Institute of Polymer Mechanics, Academy of Sciencies of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 698–704, July–August, 1968.     

Flow of polymer melts in a combined extruder

A viscoelastic incompressible fluid, modeled by the White-Metzner equation, flows in a combined extruder. Approximate expressions are obtained for the secondary flows in the disk zone of the machine whose presence has been confirmed experimentally. By means of these expressions it is possible to determine the total shear deformation of an element of the melt as it passes through the extruder.Kiev Polytechnic Institute. L'vov Polytechnic Institute. Translated from Mekhanika Polimerov, No. 2, pp. 351–358, March–April, 1972.