Structure formation in a crosslinked polyethylene melt crystallizing under uniaxial tension

The formation of supermolecular structure has been investigated in the case of medium-pressure polyethylene film subjected to a dose of 30 Mrad of n, radiation. The melt, prestretched at 160°C to various degrees of elongation , was crystallized at constant temperature. The results are interpreted on the basis of an analysis of the effect of the mechanical field on the growth kinetics and the orientation relative to the direction of extension of the individual crystallites; the first factor determines the shape and the second the sign of the spherulite.Institute of High-Molecular-Weight Compounds, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 1, pp. 3–6, January–February, 1971.     

Stability loss in an infinite plate with a circular inclusion under uniaxial tension

Loss of stability under uniaxial tension in an infinite plate with a circular inclusion made of another material is analyzed. The influence exerted by the elastic modulus of the inclusion on the critical load is examined. The minimum eigenvalue corresponding to the first critical load is found by applying the variational principle. The computations are performed in Maple and are compared with results obtained with the finite element method in ANSYS 13.1. The computations show that the instability modes are different when the inclusion is softer than the plate and when the inclusion is stiffer than the plate. As the Young’s modulus of the inclusion approaches that of the plate, the critical load increases substantially. When these moduli coincide, stability loss is not possible.     

Elastic properties of microcomponents under uniaxial stress

In order to develop highly stressable microcomponents for various applications, the structural behavior of such parts has to be examined with respect to an accurate prediction of the elastic and plastic characteristics. When simulating microparts, the major challenge is to capture the significant material heterogeneities, which are the result of the small geometrical dimensions of the components being of the same order of magnitude as the grain size. For this reason, the concept of effective properties fails and apparent properties have to be considered. In this paper we examine the elastic properties of microspecimens made of gold. Therefore, various finite element simulations have been evaluated statistically in order to identify the characteristic parameters of the distribution. Polycrystals are modeled as a periodic Voronoi tesselation with a uniform distribution of crystal orientations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of hydrostatic pressure combined with uniaxial tension on certain physical properties of polymers

The residual changes in the density and swelling properties of high-density polyethylene, teflon, PVC, and ebonite after extension under hydrostatic pressure have been investigated. It is shown that in this case the density of all the materials tested is higher and the swelling lower than in the case of uniaxial tension alone. This effect of hydrostatic pressure is attributable to the creation of favorable conditions for the healing of cracks formed in the deformation process.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1018–1023, 1967     

Hoop stress calculation for a nearly circular hole in a finitely deformed plate under plane strain and uniaxial tension

This work applies the theory of small deformations superposed on an exact finite solution (see Green/Zerna [2], Graham [7]) to discuss the plane strain deformation of a plate of incompressible Mooney-Rivlin material containing an almost circular hole and which is expanded by a radial pressure at this hole and uniaxial tension at infinity.As a specific example, we consider the theory as it applies to an elliptic hole of small eccentricity. The resulting differential equations are solved using Colsys [12, 13], a recent numerical technique for handling boundary value problems for families of ordinary differential equations, and graphs of hoop stress are drawn against finite extension for various values of eccentricity and uniaxial tension.

---

Zusammenfassung Die vorliegende Arbeit wendet die Theorie der kleinen, einer exakten Lösung überlagerten, Deformationen an. um die ebene Verzerrung einer Platte aus inkompressiblem Mooney-Rivlin-Material zu diskutieren, die ein fast rundes Loch enthält und beansprucht wird durch Radialdruck an diesem Loch und einachsige Spannung im Unendlichen.Als spezielles Beispiel betrachten wir die Anwendung der Theorie auf ein elliptisches Loch mit kleiner Exzentrizität. Die resultierenden Differentialgleichungen werden durch Colsys [12, 13] gelöst. Dies ist eine neue numerische Methode, um Randwertprobleme für Familien von gewöhnlichen Differentialgleichungen zu lösen. Es werden Graphen der Tangentialspannung in Funktion der endlichen Dehnungen für verschiedene Werte von Exzentrizität und einachsiger Spannung aufgezeichnet.

---

---

Visited Simon Fraser University during the academic year 1982/83.     

Strength of orthogonally reinforced plastics in uniaxial tension

Failure conditions are proposed for an orthogonally reinforced plastic in uniaxial tension at an arbitrary angle to the directions of reinforcement. The failure conditions are formulated for the case when the strength of the bond between the resin and the reinforcement is greater than the strength of the resin. The strength of the resin, which is in a volume state of stress, is determined by an energy criterion.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 629–633, July–August, 1973.     

Homogeneous uniaxial tension of polyethylenes. Temperature effect

Mechanics of Composite Materials - The effect of temperature on the process of homogeneous uniaxial tension of polyethylenes of different crystallinity is analyzed by means of an analytic formula...     

Deformation of thin polycaprolactam film in uniaxial tension

The individual stages of deformation of spherulitic specimens of polycaprolactam have been studied by a microscopic method. An empirical relation between the total deformation of the specimen and the deformation of the individual spherulite is obtained.     

Creep of reinforced plastics in uniaxial tension along the fibers

Relations are proposed for determining at any moment of time the strains in a reinforced plastic stressed in the resin and the reinforcement by a constant tensile load as a function of the reinforcement ratio and the rheological properties of the reinforcement and resin. The proposed relations agree quite well with the experimental data.Mekhanika Polimerov, Vol. 1, No. 6, pp. 69–77, 1965     

Effect of uniaxial tension on the density distribution in polycaproamide

The effect of uniaxial tension on the density of polycaproamide has been studied in the temperature region from +20 to +150°C. The density measurements were made by the flotation method. It is shown that the relative change of density increases with temperature. An empirical formula for the density distribution along the stretched specimen is proposed.Severodonetsk Glass-Reinforced Plastics Plant. Lugansk Mechanical Engineering Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 760–761, July–August, 1968.     

Development of slits in polyethylene and polypropylene films stressed in uniaxial tension

Optical microscopy has been used to investigate the development of a slit in polyethylene and polypropylene films with spherulites of different types and sizes stressed in uniaxial tension. The angle between the slit and the direction of extension was 0, 45, or 90°. Slits at 45 and 90° initially develop through localization of slits by a stronger oriented polymer and subsequently as a result of failure of the oriented polymer at the tip of the slit. A longitudinal slit does not develop and does not affect the deformation of the film.Mekhanika Polimerov, Vol. 3, No. 1, pp. 95–98, 1967     

Dynamic mechanical properties of a heavily filled rubber

The acoustico-mechanical properties of a heavily filled rubber (70% by vol. NaCl) are investigated over a broad frequency-temperature interval. It is shown that there are various qualitative differences as compared with unfilled polymers. The effects of tensile strain and hydrostatic pressure on the dynamic properties of a heavily filled rubber are also determined.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 4, 688–692, July–August, 1968.