Experimental methods of investigating the state of stress of glass-reinforced plastic shells

A method of testing glass-reinforced plastic shells under external hydrostatic pressure is described together with a procedure for determining the elastic properties of the material of which the shell is composed. Test data on the strength and stability of shells subjected to external hydrostatic pressure are presented.Leningrad. Translated from Mekhanika Polimerov, Vol. 5, No. 1, pp. 157–163, January–February, 1969.     

Procedure for measuring the thermophysical properties of polymers at high hydrostatic pressures

A procedure is suggested for determining the thermophysical properties of solids under hydrostatic pressure conditions by the instantaneous cylindrical heat source method without allowance for heat exchange at the sample-liquid boundary. A calculation performed showed that the temperature field of a cylinder of finite radius is identical to the temperature field of an infinite body up to Fo=0.05–0.07 with an accuracy far better than 0.5%. It is shown that the sample dimensions can be small thereupon at measurement times sufficient for performing the measurements on a standard apparatus of the order of 40–70 sec.Moscow Chemical Engineering Institute. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 568–570, May–June, 1973.     

Experimental investigation of forces affecting the formation of fiberglass plastic structures by winding

A method is suggested for the investigation of pressure occurring in the winding of glass fiber plastic coils, at tensions of the glass reinforcement used in practice.Translated from Mekhanika Polimerov, No. 5, pp. 938–940, September–October, 1972.     

Influence of hydrostatic pressure on the lifetimes of polymers

Under uniaxial tension, the lifetimes of polymers under hydrostatic pressure are longer than under atmospheric pressure. This effect is attributed to a change in the failure mechanism under pressure owing to retardation of the free-radical chain reaction of breakage of the macromolecules under omnidirectional compression.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 2, pp. 207–213, March–April, 1976.     

Concerning extruder flow

A criterial equation for determining the energy dissipation in the channel of an extruder screw is obtained analytically for a Newtonian model of the extrudate. It is shown that for actual extruders the dissipation does not depend on the pressure in the die.Moscow Region. Translated from Mekhanika Polimerov, No. 5, pp. 924–927, September–October, 1969.     

Deformation of a glass-reinforced plastic cylindrical shell encased in a thick-walled elastic cylinder

A solution is given for the axisymmetric problem of the deformation of an orthotropic glass-reinforced plastic shell of finite length encased in a soft transversely isotropic cylinder under internal pressure.Moscow Institute of Heat Engineering. Translated from Mekhanika Polimerov, No. 1, pp. 164–168, January–February, 1973.     

Effect of material structure on the stability of a laminated-plastic cylindrical shell

A compact equation is proposed for analyzing the stability of layered shells in relation to their structure. The case of a shell with split longitudinal-transverse winding subjected to hydrostatic pressure is investigated.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 1, pp. 147–150, January–February, 1971.     

Nonlinear dynamical problem of a cyclinder with a slowly changing internal boundary

The problem of a hollow viscoelastic cylinder enclosed in an elastic shell is examined. The inside diameter varies. A nonlinear cubic theory is used to describe the relation between the stresses and strains in time. A vibration analysis is carried out for variable internal pressure.Moscow Institute of Electronic Machine Building. Translated from Mekhanika Polimerov, No. 2, pp. 274–280, March–April, 1973.     

Influence of elevated hydrostatic pressure on the diffusion constants of polymer materials

The authors give experimental results showing how the diffusion constants of various polymer materials depend on the (elevated) hydrostatic pressure.A. A. Zhdanov Leningrad State University. Translated from Mekhanika Polimerov, No. 2, pp. 344–346, March–April, 1974.     

The design of low-wear friction materials

The relation between the elastoplastic characteristics of the friction surface and contact pressure is analyzed on the basis of the molecular-mechanical theory of friction. A criterion for predicting certain physico-mechanical properties necessary to ensure high wear resistance over a broad temperature interval is proposed.State Scientific-Research Institute of Machine Science, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 298–302, March–April, 1969.     

Energy dissipation from an extrudate in the gap between the screw rib and the extruder shell

A dimensionless equation is derived for determining the energy dissipation between the screw rib and the sleeve of an extruder for a Newtonian model extrudate. The parameter ranges, within which the pressure at the exit from the screw and some geometrical parameters do not affect the dissipation, are indicated.Moscow Institute of Chemical Engineering. Translated from Mekhanika Polimerov, No. 4, pp. 746–749, July–August, 1972.     

Creep of fluoroplastic under the joint action of tension and hydrostatic pressure

Conclusions 1. The effect of hydrostatic pressure on the creep of Teflon has been investigated under isothermal conditions. The applicability of the principle of reduced variables for reduction of creep curves with respect to pressure has been shown.2. It has been ascertained that in the pressure region from atmospheric to 1600 kgf/cm² there are two subregions, which are separated by a transition at a pressure of 700–800 kgf/cm². It has been shown that in these subregions the occurrence of relaxation processes has different characters.3. A direct measurement of the free volume of Teflon has been made in the temperature range from 40 to 120°C. A sharp increase in free volume in the region of the temperature transition has been shown.Leningrad Technological Institute of the Refrigeration Industry. Okhtinsk Scientific and Industrial Union "Plastpolimer," Leningrad. Translated from Mekhanika Polimerov, No. 3, pp. 434–438, May–June, 1977.     

Temperature stresses in a long hollow viscoelastic cylinder with variable inner boundary

As distinct from existing solutions for the state of stress and strain, in addition to the stresses created by internal pressure acting on the moving inner surface, the thermal stresses created by a temperature field are also taken into account. A solution is obtained using tabulated singular kernels of the hereditary theory of viscoelasticity.Moscow Lomonosov State University. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 219–226, March–April, 1969.     

Force and energy parameters of the process of viscoelastic polymer flow between calender rolls

Polymer flows between rolls are treated as continua whose rheological behavior is described by a Maxwell model. Analytic expressions in quite simple and convenient form are obtained for the pressure gradient and the contact forces of friction. These are easily converted into relations for the specific pressure, thrust, and effective power for given starting parameters. The solutions obtained correctly reflect a number of qualitative characteristics of the flow of viscoelastic polymers. A comparison with the experimental data shows that the proposed method is suitable for use in engineering practice.Leningrad Lensovet Technological Institute. Translated from Mekhanika Polimerov, No. 4, pp. 734–738, July–August, 1970.     

Dynamics and optimization of cylindrical composite shells

The stability of cylindrical composite shells under dynamic external pressure is discussed. A criterion for determining the load-carrying capacity based on Malmeister's equation with respect to bending parts of deformation is proposed. Optimization of the shell mass relative to various structural parameters has been carried out as a nonlinear programming problem. Numerical results are given.Translated from Mekhanika Kompozitnykh Materialov, Vol. 31, No. 1, pp. 81–87, January–February, 1995.     

Calculation of the long-term strength of thin-walled polymeric tubes under biaxial loading

The problem on calculating the failure time of thin-walled polymer tubes in creep under internal pressure, internal pressure with tension, pure torsion, and torsion with tension is solved. The solution is constructed based on the concept of equivalent stresses. A mixed long-term failure criterion taking into account the sings of principal stresses is used as the equivalent stress. The calculation results are in a satisfactory agreement with experimental data.Translated from Mekhanika Kompozitnykh Materialov, Vol. 40, No. 6, pp. 811–826, November–December, 2004.     

Plane-stress creep of a glass-reinforced plastic

The creep behavior of an orthotropic glass-reinforced plastic based on Polimal'-109 resin and 19-S4 glass fabric is described. A special device for testing tubular specimens in plane-stress creep has been designed. The loading conditions include combined torsion and tension, internal pressure, and loading along the principal directions of anisotropy. Constitutive equations describing creep and recovery are proposed for the two-dimensional case.Warsaw. Translated from Mekhanika Polimerov, No. 3, pp. 398–410, May–June, 1971.     

Emergy-based analysis of Beijing–Tianjin–Tangshan region in China

An emergy-based analysis was conducted for the Beijing–Tianjin–Tangshan urban agglomeration district from perspectives of emergy density, resource structure, environmental pressure and resource use efficiency during the period of 1991–2005. The results showed that Beijing, Tianjin and Tangshan as contiguous regions shared similar characters and evolving trends in certain aspects as emergy intensity and proportion of local renewable resources on the whole. As for the local resources availability, process efficiency and environmental pressure, however, these three cities have significant differences. With comparison of the other cities in China, it is shown that Beijing–Tianjin–Tangshan region has higher environment loading and lower sustainability level though enjoying rapid urbanization process and economic development. This study also suggests that the first priority on economic development competition within urban agglomeration regions may lead to the wasting of resources and redundant construction, while cooperative and rational selection for development pattern are the proper choice for coordinate regional development and long term sustainability to overcome resource restrictions.     

General criteria of the strength of isotropic media

The limit surfaces of isotropic materials are considered in the invariant spaces of the stress tensor. The general requirements that must be met by limit surfaces are formulated. A three-invariant strength criterion for isotropic media sensitive and insensitive to hydrostatic pressure is given in general form. The convenience of analyzing strength criteria in the two-dimensional space of the base invariants of the stress tensor is demonstrated.Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 251–261, March–April, 1971.     

Effect of hydrostatic pressure on the viscosity of failure of polymeric materials

Conclusions A setup and method were developed for studying the effect of hydrostatic pressure on the characteristics of the crack resistance of polymeric materials. The viscosity of failure of material K-4I based on butyl rubber was determined in a wide range of rates of crack propagation and hydrostatic pressures. It was found that an increase in the hydrostatic pressure increases the resistance to crack propagation in a polymeric material. The pressure-time analogy method, where the dependences of the viscosity of failure on the rate of crack growth are parallelly shifted to the value of the pressure-time shift and a generalized curve is formed, can be used for taking the effect of the pressure into consideration.Translated from Mekhanika Kompozitnykh Materialov, No. 6, pp. 973–977, November–December, 1986.