Method of determining the volume and shear characteristics of elastico-viscous hereditary media from uniaxial-tension (compression) experiments

A method is proposed for determining the elastic constants — instantaneous modulus of elasticity, Poisson's ratio, shear modulus, bulk modulus, and the shear and volume influence functions — the shear creep kernel, the shear creep rate kernel, and the corresponding relaxation kernels from the data of creep or relaxation tests.Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 754–758, 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.     

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.     

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.     

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.     

Ultrasonic method of determining the elastic characteristics of anisotropic materials

An ultrasonic method of determining the elastic characteristics, developed for isotropic materials and based on the measurement of the angles of total internal reflection of ultrasound at a liquid-solid interface, is applied to an anisotropic Compreg of the DSPA type. The results obtained for the shear modulus using the ultrasonic method at 2.5 MHz and an independent method based on measuring the frequency of the damped torsional vibrations of a prismatic bar at 10–30 Hz are compared. It is shown that the shear modulus varies only slightly (10–12%) on the frequency interval investigated.Leningrad Kirov Forest Engineering Academy. Translated from Mekhanika Polimerov, No. 4, pp. 728–731, July–August, 1969.     

Periodic axial and shear deformation of polymers in the viscous-flow state

Results are given of an experimental investigation of the combined periodic axial and shear deformation of polymers in the viscous-flow state. Specimens in the form of right cylinders were disposed between two parallel plates to which the material adhered completely. The experimental data are compared with those obtained under simple shear. The results indicate that, with combined periodic axial and shear deformation, nonlinear shear deformations affect the axial viscoelastic properties and nonlinear axial deformations affect the shear properties of the material.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 880–885, September–October, 1972.     

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.     

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.     

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.     

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.     

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.     

Barus effect in polymer flows through cylindrical and flat dies

The determination of the swell factor of a polymer jet extruded from a cylindrical or flat die is examined. Relations are obtained for the dependence of the swell factor on shear rate and shear stress, expressed in terms of the constants of the rheological model.Scientific Research Institute of Plastics, Moscow. Kiev Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 487–492, May–June, 1976.     

Mechanism of shear failure of reinforced rings in bending

The mechanism of failure of a ring due to the shear stresses in the matrix is investigated. It is shown that in the process of shear failure the axial displacement distribution is modified and that the shear failure mechanism depends on the type of loading. The load corresponding to the onset of failure of the ring due to the shear stresses in the matrix does not exhaust the carrying capacity of a reinforced ring with respect to this mode of failure.Institute of Hydrodynamics, Siberian Division of the Academy of Sciences of the USSR, Novosibirsk. Translated from Mekhanika Polimerov, No. 3, pp. 435–444, May–June, 1976.     

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.     

Rheological Properties of Nanosized AlN Powder Suspensions for Advanced Ceramics

The rheological properties (flow curves and viscoelastic behavior) of injection molding suspensions of a plasma-processed AlN nanosized powder (nanopowder) in paraffin are investigated over a broad range of shear rates (0.07–1350 s^–1). Two viscosity plateaux are observed on the flow curves and two values of the yield stress are obtained. The lower value of the strain amplitude (0.66%), exceeding the linearity limit of periodic shear, is restricted by the rheometer resolution. The ultrasound treatment and shear deformation of suspensions affect the structure of particle packing, which is responsible for the dependence of their rheological properties on the prehistory of mechanical actions.     

Experimental determination of the transverse shear modulus of a wound glass-reinforced plastic in creep

It is proposed to determine the interlayer shear modulus in creep starting from the results of bending tests on simply supported beams with a concentrated load. It is assumed that the increase in deflection with time is caused by interlayer creep. The data of creep tests on wound glass-reinforced plastic beams are presented and used to determine the long-time interlayer shear modulus.Leningrad. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 370–372, March–April, 1969.     

Moduli of elasticity of polymer melts

The physical significance of the so-called initial modulus, determined in measuring the rheological properties of thermoplastic melts from the initial slope of the time dependence of the stresses at given constant shear rate, is considered. It is shown that this quantity is related with the ratio of the shear and normal stresses.Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 534–538, May–June, 1969.     

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.     

Hybrid Simulation of Space Plasmas: Models with Massless Fluid Representation of Electrons. IV. Kelvin–Helmholtz Instability

This is a survey of the literature on hybrid simulation of the Kelvin–Helmholtz instability. We start with a brief review of the theory: the simplest model of the instability—a transition layer in the form of a tangential discontinuity; compressibility of the medium; finite size of the velocity shear region; pressure anisotropy. We then describe the electromagnetic hybrid model (ions as particles and electrons as a massless fluid) and the main numerical schemes. We review the studies on two-dimensional and three-dimensional hybrid simulation of the process of particle mixing across the magnetopause shear layer driven by the onset of a Kelvin–Helmholtz instability. The article concludes with a survey of literature on hybrid simulation of the Kelvin–Helmholtz instability in finite-size objects: jets moving across the magnetic field in the middle of the field reversal layer; interaction between a magnetized plasma flow and a cylindrical plasma source with zero own magnetic field.