Mechanism by which tension on the fibrous filler affects the structure and the strength of wound glass-plastics

Conclusions 1. We have studied how the structure of glass-plastics wound with twisted threads is affected by tension on the fibrous filler. The trend of changes in fiber content and porosity, as well as an increasingly nonuniform distribution of the reinforcing filler over the thickness, has been established.2. The effect of a nonuniform filler distribution over the thickness on the tensile strength has been evaluated. The calculated and the experimental curve of strength as a function of the tension have been compared, the former taking into account variable porosity, fiber content, and nonuniformity of fiber distribution over the thickness.3. It has been demonstrated that the change in the strength characteristics of a wound glass-plastic as a function of the tension on the reinforcing filler during winding is due to a combined complex effect of such factors as the overall fiber content and porosity, a nonuniform fiber distribution over the thickness, the fiber orientation, and the degree of mechanical damage in threads due to their interaction with the active components of the winding machine.Report presented at the Third All-Union Conference on Polymer Mechanics. Riga, November 10–12, 1976.Translated from Mekhanika Polimerov, No. 3, pp. 439–444, May–June, 1977.     

Determination of the electron temperature of a degenerate semiconductor in quantizing fields under heating by an electric field

Investigations of the Shubnikov-de Haas oscillation of the transverse magnetoresistance due to the magnitude of the electric field in n-type InSb with 5 · 10¹⁵, 3 · 10¹⁶ cm^–3 concentrations at a 4.2 °K temperature are carried out herein. A method is proposed to determine the electron temperature T_e; dependences of T_e on the electric and magnetic fields in the sample are obtained for a transversely oriented magnetic field. The relaxation time of the electron energy is estimated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 96–100, February, 1972.     

Temperature dependence of the mechanical properties of Cu-Ti and Cu-Ti-Al alloys

A study has been made of the temperature dependence of the mechanical properties and mechanical twinning of the alloys Cu + 4.3% Ti (I) and Cu + 2.3% Ti + 2% Al (II) in the single-phase state and in a state with a developed modulated structure. A correlation is found between the (T) dependence and the development of mechanical twinning in the range 90–673 °K. The temperature dependence of the strength of the alloy Cu + 2.3% Ti + 5% Al containing incoherent stable-phase inclusions was studied. The experimental (T) dependence is compared with the theoretical dependence, and the activation energy and volume of plastic flow are determined.Translated from Izvestiya VUZ. Fizika, No. 4, pp. 114–120, April, 1970.     

Kinetics of dispersion hardening and change in slip mechanism in Cu-Ti and Cu-Ti-Al alloys

It is shown in this paper that the hardening of Cu-Ti and Cu-Ti-Al alloys at the coherent-decomposition stage can be described in terms of the basic Mott-Nabarro mechanism. The overaging stage in Cu-Ti alloys is due to the partial loss of coherence of the -phase, though cutting of the particles by dislocations continues. In Cu-Ti-Al alloys bypassing of the particles in the way suggested by Orowan offers a possible deformation mechanism at the overaging stage. These conclusions are supported by the slip patterns obtained by electron microscopy of replicas. The small difference between the slip patterns of specimens having been quenched and those having been aged to give maximum mechanical properties should be particularly noted, since it is at variance with the data already available, mostly from aluminum alloys.     

Note: A conjecture on partitions of groups

We conjecture that every infinite group G can be partitioned into countably many cells \(G = \bigcup\limits_{n \in \omega } {A_n }\) such that cov(A _n A _n ^?1 ) = |G| for each n ∈ ω Here cov(A) = min{|X|: X} ? G, G = X A}. We confirm this conjecture for each group of regular cardinality and for some groups (in particular, Abelian) of an arbitrary cardinality.