Bending of long rectangular plates with low shear strength

The bending of rectangular glass-reinforced plastic plates is investigated for various edge conditions on the basis of generalized applied theories of the Timoshenko and Ambartsumyan types [4]. A series of qualitative and quantitative differences is obtained as compared with the corresponding results of the classical Kirchhoff theory [1].L'vov Polytechnic Institute; Ivano-Frankovsk Institute of Oil and Gas; Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 945–950, September–October, 1969.     

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.     

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.     

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.     

On the applicability of two-dimensional applied theories to problems of the stability of axially loaded cylindrical shells made of materials with low shear stiffness

The applicability of two-dimensional applied theories of the Kirchhoff-Love, Timoshenko, and Ambartsumyan types to problems of the stability of shells with low shear stiffness [1] is discussed. The critical loads given by these theories are compared with those recently obtained [6–8] by solving the problem of the stability of a cylindrical shell on the basis of general solutions [3, 4] of the three-dimensional linearized equations of the theory of elasticity [5].Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. L'vov Polytechnic Institute. Translated from Mekhanika Polimerov, No. 1, pp. 141–143, January–February, 1970.     

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.     

Resistance of glass-reinforced plastics to long-term shear failure

The time dependencies of the strength of glass-reinforced plastics in shear under steady, continuous and alternating loads are examined. Failure under steady and continuous loading is depicted by means of an exponential model of the build-up of damage.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, No. 2, pp. 295–302, March–April, 1970.     

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.     

Experimental determination of the influence of periodic shear deformation and filling on the effective viscosity of solutions of synthetic rubber

The influence of periodic shear deformation on the effective viscosity of filled solutions of synthetic rubber has been studied. The study was carried out on an amplitude-frequency viscosimeter developed by the authors. It has been established that during periodic deformation a linear region exists in which the effective viscosity is independent of the vibration rate, and a nonlinear region where the effective viscosity of the solutions decreases with increase in amplitude of the speed of relative deformation.Presented at the IV Symposium on Rheology of Polymers at the A. V. Topchiev Institute for Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow, May 27–30, 1969.Institute for Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, 514–520, May–June, 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.     

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.     

Study of the impact shear strength of polymer materials

A method is proposed for studying the dynamic strength of block polymers in terms of their resistance to impact shear. An original instrument for conducting tests are room and elevated temperatures is described. The results obtained with this instrument for alkathene and styrene carylonitrile copolymer are discussed. It is found that there is a considerable increase in specific shear energy in the region of transition from the glassy to the high elastic state. In the case of alkathene the investigated characteristic falls linearly on the temperature interval studied.Leningrad Kirov Institute of the Textile and Light Industries. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1135–1137, November–December, 1968.     

Probability characteristics of the shear modulus of glass-reinforced plastics

The results of tests on wound glass-reinforced plastic specimens based on ÉFB-4 epoxy-phenolic-butyral composition and NS 55/6 glass strand reinforcement with a paraffin finish have been subjected to a statistical analysis with the object of determining the probability characteristics of the shear modulus. The shear modulus is determined for unidirectional structures and structures with reinforcement ratios of 1:1, 1:2, and 3:2. The results of the tests are used to determine the mathematical expectation, variance, and probability density function of the shear modulus.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 1, pp. 160–162, January–February, 1973.     

Determination of the shear strength of the metal-plastic adhesion bond and its response to lubrication

A new method of determining the shear strength of the metal-plastic adhesion bond is considered. Experimental data on its dependence on load and indenter dimensions are presented for various types of plastics under different conditions.State Scientific Research Institute of Machine Science, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 854–858, September–October, 1970.     

Region of applicability of applied theories in problems of the stability of bars and plates with low shear stiffness subjected to uniaxial compression

The question of the region of applicability of applied theories of bending of bars and plates in stability problems is discussed in relation to the case of uniaxial compression. The critical loads given by these theories are compared with the recently obtained solution [4, 5, 7–10] based on the three-dimensional linearized equations of the theory of elasticity [6]. It is established that for the problems in question the Timoshenko and Ambartsumyan theories are accurate enough for engineering purposes over the entire practical region of variation of the geometric and physical parameters of the bar (plate), whereas the use of the Euler-Bernoulli and Kirchhoff-Love theories may lead to unacceptable errors.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev; Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga; Lvov Polytechnic Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1124–1126, November–December, 1969.     

Fatigue strength of glass-reinforced plastics (GRP) in shear in the plane of reinforcement

The results of an investigation of the fatigue strength of three grades of glass-reinforced plastic are described. It is shown that cyclic loading with gradually increasing stress amplitude can be used to determine the fatigue strength at a given ambient temperature and loading frequency.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 928–931, September–October, 1975.     

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.     

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.     

Effect of relaxation parameters on the behavior of rigid polymers in pure shear

The authors have investigated the effect of the relaxation parameters of a rigid polymer corresponding to the individual terms of the relaxation spectrum on the nature of the theoretical curves calculated for creep, strain relaxation and loading at constant strain rate in pure shear on the assumption that the stress-strain relation is described by the generalized Maxwell equation.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 431–436, May–June, 1969.     

Relationship between the normal and shear stresses in elastico-viscous liquid flow

A class of elastico-viscous liquids is considered. On the basis of an analysis of the experimental data of a considerable number of authors it is shown that the Weissenberg relation between the shear stresses and the first difference of the normal stresses is limited and a more general expression of the exponential type is proposed.Institute of Thermophysics, Siberian Division, Academy of Sciences of the USSR, Novosibirsk. Translated from Mekhanika Polimerov, No. 1, pp. 126–128, January–February, 1970.