Deformation of teflon in linear and plane states of stress

Teflon specimens have been deformed in accordance with various laws of variation of stress and strain with time under plane stress conditions. Fairly simple expressions describing the relation between the stresses and large (up to 60% relative to the initial dimensions) strains are constructed for a broad class of loading regimes.Scientific-Research Institute of Mathematics and Mechanics, A. A. Zhdanov Leningrad State University. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 742–746, July–August.     

Nonlinear hereditary model including temperature effects in various stress states

For an isotropic viscoelastic medium subjected to uniaxial loading, it has been shown that the parameters of the material (three parameters and the instantaneous deformation curve) can be determined on the basis of a limited number of experiments. These same parameters were used in calculating a complex stress state. Results are presented for various temperatures and loading rates. Experimental data have been compared with the results of theoretical calculations. Formulas for determining the resolvent of the hereditary equation have been derived.Paper presented at the Ninth International Conference on the Mechanics of Composite Materials, Riga, October, 1995.A. A. Blagonravov Institute of Mechanical Engineering, Russian Academy of Sciences, Moscow, Russia. Institute of Physicomechanical Problems of the North, Russian Academy of Sciences, Yakutsk, Russia. Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 72–82, January–February, 1996.     

Deformation and stress distribution in a layered plastic

The stress distribution over the unidirectionally reinforced layers is investigated in relation to the layer thickness ratio and the direction of loading of a two-way reinforced plastic. An expression is obtained for the modulus of elasticity of the layered plastic in an arbitrary direction relative to the directions of reinforcement. The effect of the geometry of the structure of the layered material on its deformation properties is experimentally illustrated.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 563–570, May–June, 1972.     

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.     

Constitutive modeling of cyclic stress softening in filled elastomers

Quasi-static cyclic loading tests on filled rubber-like materials reveal a significant stress softening in the first cycle. The magnitude of this softening, widely known as the Mullins effect, reduces in the next cycles until it reaches a stabilized value referred to as hysteresis. In this contribution, we associate the hysteresis with the fracture of carbon bonds in the filler network. In order to calculate the cyclic energy dissipation, we modify the classic concept of network decomposition [1, 2] and add a new network considered to be responsible for the breakage and re-formation of carbon black aggregates during loading and unloading. The proposed model is in-line with a wide range of experimental observations. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Experimental investigations on the mechanical behavior of filled rubber

A lot of experimental results on the elastic as well as on the inelastic behavior of elastomer materials are known. However, so far now systematic examination on defined rubber mixtures has been reported. In this presentation the phenomenology of elastomer materials is characterized on the basis of extension and compression tests performed with dumbbell– and S2–specimen. Stiffness, upturn (stiffness at final deformation), hysteresis and remaining deformation have been analyzed for well defined rubber systems and environmental conditions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nonlinear creep of a glass fabric-reinforced plastic in several complex states of stress

Tensile, compressive, torsional, and combined creep tests have been performed on tubular specimens of a glass fabric-reinforced plastic. The sign of the normal stress has been found to have an important influence on the development of the shear creep strains. The rheological parameters of the material necessary for approximating the test curves have been determined and the results of the calculations compared with experiment.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 2, pp. 212–218, March–April, 1973.     

Singular behavior of vacuum states for compressible fluids

In this survey paper, we will present the recent work on the study of the compressible fluids with vacuum states by illustrating its interesting and singular behavior through some systems of fluid dynamics, that is, Euler equations, Euler–Poisson equations and Navier–Stokes equations. The main concern is the well-posedness of the problem when vacuum presents and the singular behavior of the solution near the interface separating the vacuum and the gas. Furthermore, the relation of the solutions for the gas dynamics with vacuum to those of the Boltzmann equation will also be discussed. In fact, the results obtained so far for vacuum states are far from being complete and satisfactory. Therefore, this paper can only be served as an introduction to this interesting field which has many open and challenging mathematical problems. Moreover, the problems considered here are limited to the author's interest and knowledge in this area.     

Deformation behavior and strength of unidirectional carbon fiber laminates

The elastic deformation behavior and the load-carrying capacity of unidirectional carbon fiber laminates under static loading at room and cryogenic (down to 77 K) temperatures are investigated. The possible ways of predicting their elastic and strength characteristics proceeding from the volume content and mechanical parameters of fibers and matrix are analyzed. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 583–598, September–October, 2006.     

Uniqueness and asymptotic behavior of coexistence states for a non-cooperative model of nuclear reactors

In this paper, we analyze the asymptotic behavior of coexistence states for a non-cooperative model of nuclear reactors. In addition, we also present some remarks on the uniqueness of coexistence states in a high dimensional case. Our results complement the work of López-Gómez [J. López-Gómez, The steady states of a non-cooperative model of nuclear reactors, J. Differential Equations 246 (2009), 358-372].     

Asymptotic behavior of the transition probability of a homogeneous Markov process with a finite number of states in a series model

The asymptotic behavior of the transition probabilities P_ij ⁽ⁿ⁾(t/_n) for a homogeneous stochastically continuous Markov process with a finite set of states E where E can be represented in the form E=E₀ U E₁ U ... U E_r, E₀ is the set of unessential states, E_k, k=1, ..., r are ergodic classes.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 4, pp. 574–576, April, 1992.     

Temperature dependence of deformative properties of filled polyvinyl chloride of various degrees of plasticization in the highly elastic state

Conclusions 1. The relative increase in stiffness upon the filling of PVC in the highly elastic state decreases with increase in temperature according to an exponential law.2. For a given degree of filling, the relative increase in stiffness upon filling as a function of the plasticizer content in PVC composites passes through a maximum at a degree of plasticization of 5–10%.All-Union Scientific-Research Institute of the Use of Polymeric Materials in Reclamation and Water Management, Elgava. Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 646–650, July–August, 1977.