Realization of the mechanical properties of fibers in high-modulus polymer composites

The effect of scatter in the strength and deformation properties of the high-modulus fibers, the degree of twist, and the presence of pores in the polymeric matrix on the degree of realization of the potential possibilities of these fibers in composite materials is briefly considered.All-Union Scientific-Research Institute of Aviation Materials, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1123–1125, November–December, 1972.     

Effect of the rate of deformation on the mechanical properties of compact bone tissue

Conclusions The results of this study show that the ultimate stress increases with increasing deformation rate from 10^–5 to 1 sec^–1 but the initial elasticity modulus remains virtually constant. A characteristic feature of bone tissue is the significant increase or even maximum in specific deformation energy for destruction in the range of deformation rates corresponding to normal physiological conditions for bone function. The deformation diagrams of human bone tissue for the same values of moisture content and deformation rate in tensile testing do not differ from the analogous curves for the bone tissue of cattle. Quantitatively, the ultimate stress ₁₁ and the initial elasticity modulus E₁ are 5–10% and 15–25% greater, respectively, than for cattle bone tissue, while the ultimate deformation eu is virtually the same. An increase in the moisture content of bone tissue leads to a more pronounced dependence of the mechanical parameters on the deformation rate.Translated from Mekhanika Kompozitnykh Materialov, No. 3, pp. 512–517, May–June, 1982.     

Vibrational frequency shifts in the stretched polypropylene molecule

The GF matrix method is used to compute the changes in the skeletal vibration frequencies for a simplified model of isotactic polypropylene stretched by a loadf. The series of frequencies obtained atf=0 are identified with those experimentally observed. A linear approximation is used for the deformation potential energy atf=0–2·10^–4 dyneperchain. The results of the calculations are presented in graph form.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 586–594, July–August, 1968.     

Instability at the interface of bodies subjected to high-elastic deformations

The problem of instability at the interface of two elastic half-planes in compression is investigated within the framework of the plane problem of the stability of deformation of compressible and incompressible elastic bodies at finite subcritical strains [1, 2]. The results are obtained for the plane deformation of bodies with an arbitrary form of the elastic potential. Numerical examples are presented for high-elastic bodies with potentials of the Mooney and Treloar types.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 999–1002, November–December, 1971.     

A polymer film hardening effect

It is shown that a polyester film incapable of forced high-elastic deformation can be subjected to such deformation by stretching a film-substrate system. The resulting oriented structure is stable and on being measured from the substrate, the film exhibits a hardening effect. In this case contact with and adhesion to the substrate are a necessary condition for the development of the latent potential of the film.Lenin All-Union Electrical Engineering Institute, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 731–733, July–August, 1971.     

Physical relations for an orthotropic material in the local strains theory

Compressible and incompressible orthotropic materials are investigated. A method of constructing variants of the local strains theory describing the deformation properties of an orthotropic material is developed on the basis of the concept of an elastic potential.Institute of Polymer Mechanics, AS LatSSR, Riga. Translated from Mekhanika Polimerov, Vol. 4. No. 6, pp. 970–975, November–December, 1968.     

Effect of liquid media on the deformation of the surface layers of a polymer-metal pair in sliding friction

The relation between the high-elastic component of polyurethane deformation and the deformation of the surface layers of metals has been investigated for sliding friction in various media. The surface layers of polymer and metal are plastically deformed. There is a certain correlation between the coefficient of friction and the amount of deformation.Kiev Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, No. 1, pp. 147–149, January–February, 1970.     

On the deformation of an extended viscoelastic rod subject to finite deformations

The deformation of a polymer material subjected to tensile strain is considered with due allowance for physically linear creep at finite deformations. The deformation process is only stable in time up to a certain value of the load; under heavier loads the deformation is unstable. An expression is derived for the critical time.Institute of the Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1130–1133, November–December, 1972.     

Deformation behavior of a filled nitrile vulcanizate in various states of stress

On the basis of experimental data obtained in uniaxial and symmetrical and nonsymmetrical biaxial tension and pure shear, the deformation behavior of unfilled and filled butadiene-nitrile rubbers is described by means of the Bartenev-Khazanovich one-parameter high-elastic potential.Leningrad Branch of the Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 2, pp. 363–366, March–April, 1972.     

The effect of rate of deformation on the mechanical characteristics of plastics

An experimental investigation of the effect of the rate of deformation on the strength and modulus of elasticity of vinyl plastic and glass-reinforced laminate is described. It is established that when the rate of relative tensile deformation of vinyl plastic at 25°C is reduced from 2000×10^–6 sec^–1 to 5×10^–6 sec^–1, and that for glass-reinforced laminate from 1000×10^–6 sec^–1 to 1.3×10^–6 sec^–1, the decrease in the modulus of elasticity is about 40% and the decrease in ultimate strength 30 and 48%, as the case may be.Mekhanika polimerov, Vol. 1, No. 1, pp. 76–81, 1965     

Investigation of the deformation of a rubbery network polymer (SKN-40) in various types of states of stress

From the experimental data on equilibrium uniaxial and nonsymmetrical and symmetrical biaxial tension and pure and mixed shear it follows that the deformation behavior of SKN-40 crosslinked butadiene-nitrile copolymer is more accurately described by the Bartenev-Khazanovich high-elastic potential. The potential of the classical statistical theory of high elasticity of network polymers does not describe different types of states of stress with the same value of the material constant.Lenin Moscow State Pedagogical Institute, Laboratory for Problems in Polymer Physics. Leningrad Branch of the Scientific-Research Institute of the Rubber Industry. Translated from Mekhanika Polimerov, No. 5, pp. 840–845, September–October, 1971.     

Calorimetric investigation of the tensile deformation of polyethylene

A calorimetric apparatus for investigating the thermal effects associated with tensile deformation is described. The results of calorimetric measurements made on high- and low-density polyethylene during the deformation process are presented. It is shown that on the interval of strains and loading rates investigated the deformation of polyethylene is energetic in character.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 579–584, July–August, 1970.     

Effect of gaseous oxygen pressure on the kinetics of accumulation of residual deformation in resins

The authors studied changes in the properties of resins in the static deformed state under the effect of gaseous oxygen pressures of up to 200 atm at 25, 50, and 70° C for 20–500 days, depending on the experimental conditions. It was shown that an increase in gaseous oxygen pressure significantly affects the process of accumulation of residual deformation up to 30–40 atm while a further pressure rise has practically no effect on changes in the accumulation rate of residual deformation.Scientific-Research Institute of the Resin Industry, Moscow. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 552–554, May–June, 1973.     

Periodic simple shear deformation of polymers in the visco-fluid state

Research on the periodic deformation of polymers in the linear and nonlinear regions is reviewed. Special attention is given to the boundary of the region of linear deformation and to deformation in the nonlinear region. It is shown that deformation in the nonlinear region leads to a reversible fall in the viscosity and elasticity of the system due to the selective destruction of certain types of structural bonds. The effect of mineral fillers and the nature of their surfaces on the mechanical characteristics of polymers in the visco-fluid state is stressed. Use of the theory of thixotropy makes it possible to describe the mechanical characteristics of melts in the regions of nonlinear periodic deformation and combined periodic and steady-state deformation on the basis of the results of trivial rheological measurements.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, Vol. 5, No. 1, pp. 182–188, January–February, 1969.     

Effect of moisture content on the microdeformation of compact bone tissue in tension

Conclusions The x-ray diffraction results indicate the following major features for the microdeformation of bone tissue. The total deformation in the elastic region is determined by the microdeformation of the mineral bone tissue component. The large yield of the mineral component indicates its relatively low elasticity modulus. The shape of the deformation curves for both dry and moist bone tissue is a factor of the combined deformation of the mineral and organic components. While the total deformation up to fracture in dry bone tissue is determined largely by microdeformation of the crystalline mineral phase, such behavior is found for moist bone tissue only in the first segment of the curve. Deformation in the second, more curved segment of the deformation curve is a factor largely of deformation of the organic bone-tissue component.Translated from Mekhanika Kompozitnykh Materialov, No. 3, pp. 530–535, May–June, 1983.     

High-frequency periodic deformation of polymers in the viscous-flow state

The propagation of high-frequency periodic vibrations in melts and solutions is considered in the case where the acoustic characteristics of the material are determined by the deformation amplitude. It is shown that in sufficiently large specimens the consequences of periodic deformation are concentrated near the vibration source, as a result of which a layer of material with strongly modified mechanical characteristics develops. It is suggested that when periodic high-frequency deformation is superimposed on steady-state flow, owing to the presence of a boundary layer there is effective slippages of the material at the vibration-emitting surfaces.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 722–728, July–August, 1973.     

Variation of the elasticoviscous characteristics of a heavily filled rubber after periodic shear deformation

The results of an investigation of the recovery of the elasticoviscous characteristics after thixotropic reduction by periodic deformation in the nonlinear zone are reported. The rate of recovery of the mechanical properties depends on the deformation frequency and the previous history of dynamic deformation is shown to affect the dependence of the elasticoviscous characteristics on the shear rate gradient. The effects of stationary and dynamic deformation regimes on the relaxation spectrum of the material are compared.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 528–533, May–June, 1969.     

State of stress and strain of plates with two equal openings in the presence of high-elastic deformation

The apparatus of the nonlinear theory of elasticity [1–3] is used to investigate the high-elastic deformation of a plate with two equal circular openings and a massive block with two cylindrical channels. Computer-calculated stress concentration factors are given for compressible and incompressible materials.Translated from Mekhanika Polimerov, No. 4, pp. 687–692, July–August, 1969.     

Temperature dependence of the deformation properties of compositions based on polyethylene and polyisobutylene

The temperature dependence of the deformation properties (deformability and recoverability) of compositions based on low-density polyethylene and polyisobutylene has been investigated. For two-component polyethylene—polyisobutylene systems this dependence varies with the component ratio. Introducing a filler (talc) reduces the recoverability of the compositions owing to increases in both the delayed high-elastic deformation and the flowability. The deformation properties of compositions plasticized with paraffin change abruptly at the melting point of the latter.Moldavian Scientific-Research Institute of the Food Industry, Kishinev. Translated from Mekhanika Polimerov, No. 4, pp. 758–760, July–August, 1971.