Dependence of the dynamic strength of a glass-reinforced plastic on the mechanical and geometric parameters of its components

The dependence of the dynamic strength of a glass-reinforced plastic on the mechanical and geometric parameters of its components is investigated.Moscow Institute of Electronic Machine-Building; All-Union Institute of Glass-Reinforced Plastics and Glass Fiber, Moscow Oblast'. Translated from Mekhanika Polimerov, No. 2, pp. 366–370, March–April, 1974.     

Investigation of the thermophysical properties of polymethyl methacrylate at high hydrostatic pressures

Conclusions 1. The experimentally observed course of heat capacity is explained by competition of contributions from the lattice and defects, on one hand, and from retarded rotators, on the other.2. An equation is proposed which describes the dependence of the thermal conductivity of polymers on pressure and which agrees with experimental data to an accuracy of ±1%.Moscow Chemical Engineering Institute. Translated from Mekhanika Polimerov, No. 5, pp. 845–851, September–October, 1976.     

Results of an experimental investigation of the residual stresses in wound glass-reinforced plastics

The results of an experimental investigation of the residual stresses in wound glass-reinforced plastic rings are presented. The residual stresses were determined by the Davidenkov method. The dependence of the maximum tensile and compressive circumferential stresses on ring thickness and polymerization temperature is investigated. The experimental data are compared with the results of calculations based on the theory proposed in [1, 2].Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1116–1119, November–December, 1970.     

Applicability of influence functions determined from quasi-static experiments for solving dynamic problems of vibration protection

Creep of shock-absorbing foamed materials and a vibration-protecting structure is investigated. The parameters of the influence functions, whose numerical realization is conducted in solving the dynamic problem of vibration protection, are determined from the creep curves by the method of logarithmic matches. The conclusions agree with the experimental.Moscow Institute of Electronic Machinery. Translated from Mekhanika Polimerov, No. 3, pp. 537–540, May–June, 1975.     

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.     

Creep on an initial small interval

The creep processes of hereditary media on a small initial interval are described, using as influence functions the resolvent functions for the generators of the Dirac function, which are employed as relaxation kernels. Equations are constructed for determining the instantaneous modulus and the parameters of these functions from experimental stress-strain diagrams obtained at three different constant loading rates.Moscow Institute of Electronic Machine Building. Translated from Mekhanika Polimerov, No. 5, pp. 945–950, September–October, 1970.     

Normal stresses associated with the flow of non-Newtonian polymer systems

It has been experimentally confirmed that the method of calculating the shear rate dependence of the normal stresses from the flow curve, proposed in [1], gives good results consistent with the experimental data. A series of simple relations proposed for estimating the initial normal stress coefficient are compared with the experimental results and it is shown that there is good agreement between calculation and experiment. In the linear region the Lodge relation, which equates the high-elastic strains to half the ratio of the normal to the shear stresses is satisfied.For communication 1 see [1].Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 714–721, July–August, 1971.     

Anisotropic ring stretched by rigid half-disks

A theoretical basis is provided for the experimental method of determining the elastic and strength properties of materials by stretching ring specimens with a pair of rigid half-disks. The equilibrium equations of the plane problem for an anisotropic ring with mixed boundary conditions are solved by means of an expansion in Fourier series with respect to the circumferential coordinate. Numerical results obtained on a computer are analyzed. The dependence of the circumferential stress concentration coefficient on various parameters is investigated.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1113–1116, November–December, 1970.     

Effect of temperature and anisotropy on the elastic constants of oriented glass-reinforced plastics

The experimental temperature dependence of the modulus of elasticity and Poisson's ratio are presented for SVAM oriented glass-reinforced plastic. The possibility of treating SVAM sheet as orthotropic at elevated temperatures is demonstrated.Institute of Chemical Physics, AS USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1026–1032, November–December, 1968.     

Mechanical properties of boron fibers

The distribution of the strength of boron fibers is examined on the basis of a large amount of experimental material. The typical defects are isolated and described. The dependence of the average strength on the length of the test fiber is investigated.State Scientific-Research Institute of Chemistry and Technology of Heteroorganic Compounds, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 641–647, July–August, 1973.     

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.     

Friction and wear of certain thermoplastic materials in physiological solution

The wear resistance of certain thermoplastics has been subjected to comparative investigation together with the velocity dependence of the coefficients of friction at various pressures and after various periods of contact with a model physiological solution.Priorov Central Scientific-Research Institute of Traumatology and Orthopedics. Moscow Technological Institute of the Food Industry. Second Moscow Pirogov State Medical Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1116–1119, November–December, 1971.     

On the theory of infrared dichroism of oriented amorphous polymers

A network model of a linear amorphous polymer is used as a basis for calculating the infrared dichroism of uniaxially and biaxially oriented material. The dependence of the dichroism on the uniaxial and biaxial stretch ratios, orientation temperature, and certain other factors is investigated. Previously published experimental data are discussed.Moscow Lenin State Pedagogical Institute, Problem Laboratory of Polymer Physics. Translated from Mekhanika Polimerov, No. 6, pp. 979–984, November–December, 1970.     

Effect of microrheological processes on the adhesion of a combination of film materials

The temperature and time functions of combination of film materials, one of which is in the glass state and the other in the glass transition state, have shown that the kinetics of the formation of the actual contact surface depend on microrheological processes. Theoretical functions for stress disrupting the adhesion bond have been proposed, and have been checked experimentally by using electron microscope and rheological methods.Moscow Technological Institute of the Meat and Milk Industry. Translated from Mekhanika Polimerov, No. 2, pp. 203–208, March–April, 1970.     

Propagation of sound in oriented polymers

The propagation of sound in oriented polymers is considered. Starting from an assumption concerning the superposition of relaxation processes in polymers, expressions are obtained for the speed and absorption of sound as functions of the relaxation spectrum, molecular orientation, and crystallinity. It is shown that the orientation dependence of the acoustic properties is more distinctly expressed in the region of the glassy state.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 437–441, May–June, 1969.     

Creep of a multilayer cylinder under nonisothermal loading

A method is proposed for calculating the creep of a multilayer cylinder under nonisothermal loading with allowance for the temperature dependence of the physico-mechanical characteristics of the material. Numerical examples are considered. The states of stress and strain of the viscoelastic and elastic components of a two-layer cylinder are compared.Baranov Central Institute of Aviation Engine Construction, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 321–327, March–April, 1969.     

Method of solving equations of motion of viscoelastic media

A new method is proposed for solving dynamic problems for viscoelastic media based on the introduction of potential functions and transformation of equations of motion. The equations obtained for potential functions are used for constructing the general solution in the case of the effect of moving loads on viscoelastic media with plane-parallel interfaces. The problem of the propagation of Rayleigh surface waves is solved independently of the form of the kernels of the linear operators; a formula is obtained for determining the velocity of the Rayleigh surface wave with an arbitrary form of the viscoelastic operators. A method of experimental determination of the kernels determining the linear viscoelastic operators is proposed.V. V. Kuibyshev Moscow Civil Engineering Institute. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 429–435, May–June, 1973.     

Procedure for determining the elastoplastic anisotropy constants and creep characteristics of glass-reinforced plastics

The dependence of the parameters of the static stress-strain and creep diagrams on the gage width and length of the specimen has been experimentally investigated. Other technical factors — the accuracy with which the specimen is mounted in the grips or wedges, the transverse strain distribution, and Saint Vanant's principle — are also considered. Recommendations are given for selecting the principal dimensions of test specimens of composites with various structures.State Scientific-Research Institute of Machine Science, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 747–754, July–August, 1970.     

Temperature-frequency reduction of the dynamic functions of black-filled rubbers in the nonlinear region

The possibility of using temperature-frequency reduction of the dynamic functions of black-filled rubbers in the nonlinear region is demonstrated and an additional applicability criterion — similar slopes of the isotherms of the amplitude dependences of the dynamic functions — is formulated. In the case of heavily filled rubbers it may be necessary to determine the constants of the Williams-Landel-Ferry equation and the reference temperature T_S from the experimental data — they may not coincide with the universal values. Master curves of the dynamic functions are obtained for a series of shock-absorbing rubbers at a shear strain amplitude =0.01.A. V. Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Scientific-Research Institute of the Rubber Industry, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 751–754, July–August, 1973.     

On the theory of orientation of linear amorphous polymers

The previously derived orientation equations are solved for uniaxial extension at constant true stress, unloading, stress relaxation, and biaxial orientation at constant strain rate. The dependence of the birefringence of biaxially oriented PMMA on the magnitude and conditions of preliminary orientation has been experimentally investigated. There is good qualitative agreement between the theoretical and experimental results.For communication 1 see [1].Lenin Moscow State Pedagogic Institute. Translated from Mekhanika Polimerov, No. 1, pp. 14–21, January–February, 1973.