Stress-Strain State in the Zone of Load Transfer in a Composite Specimen under Uniaxial Tension

The stress-strain state in the zone of load transfer in a uniaxially stretched specimen made of a unidirectional epoxy carbon-fiber-reinforced plastic (CFRP) is investigated. A parametric analysis of the influence of geometric and mechanical characteristics of the specimen on its stress-strain state is performed by means of finite-element modeling. The parameters allowing us to significantly reduce the dangerous concentration of transverse and tangential stresses are revealed. The mechanical tensile characteristics of a high-strength pultruded unidirectional CFRP are determined experimentally, and the size effect of its strength is estimated.     

Composite risers for deep-water offshore technology: Problems and prospects. 1. Metal-composite riser

Prospects for the application of advanced composites in the offshore technology of oil production are considered. The use of composites in vertical pipelines-risers seems to be the most efficient. The operating loads are studied and the attendant problems are formulated. A comparative analysis of the characteristics of metal, composite, and metal-composite deep-water risers is presented. A technique is developed for designing multilayered risers, taking into account the action of internal and external pressures, gravity, and the axial tensile force created by tensioners, as well as the residual technological stresses due to the difference in coefficients of thermal expansion, physical-chemical shrinkage, and force winding. Numerical estimations are given for a two-layered riser with an inner metal layer of steel, titanium, or aluminum alloys and a composite layer of glass- or carbon-fiber plastics formed by circumferential winding. It is shown that the technological stresses substantially affect the characteristics of the riser.Institute of Polymer Mechanics, Latvian Academy of Sciences, Riga, LV-1006, Latvia. Trondheim Technical University, Norway. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 5, pp. 577–591, September–October, 1997.     

Bending strength of oriented glass-reinforced plastics

The authors consider the effect of the low shear strength and shear stiffness of oriented glass-reinforced plastics (GRP) on the stress distribution and type of failure in bending. On the basis of relations obtained in [1] it is shown that the effect of shears on the magnitude and law of distribution of the normal and shear stresses is important only for very short beams made of materials with a low shear stiffness. An experimental study of the nature of failure in bending has revealed that the chief cause of extension of the region of shear failure of oriented GRP is the low shear strength of the material, and has made it possible to establish the limits of this region for three typical materials. Anisotropy of the elastic properties has little effect on the type of failure in bending.Mekhanika Polimerov, Vol. 2, No. 4, pp. 535–542, 1966     

Variation of prestress in filament-wound glass-reinforced plastics

The authors examine the process of winding prestressed parts from oriented glass-reinforced plastics. It is shown that the essential anisotropy of the properties of these materials in responsible for variation of the specified prestress. The law of distribution of the tensile forces is investigated in the linear-elastic approximation for the case of a ring wound onto a rigid mandrel. A method of calculation is proposed that permits the change in prestress to be estimated and gives the critical number of turns beyond which the pressure on the mandrel ceases to increase.Mekhanika Polimerov, Vol. 2, No. 2, pp. 278–284, 1966     

Studies in the field of oxygen-containing heterocycles

2-Chloro- and 2,3-dichlorotetrahydropyrans add to vinyl acetate in the presence of SnCl₄ with the formation of the corresponding gem-acetoxychlorides. The addition of 2-chlorotetrahydropyran to isopropenyl acetate is accompanied by the splitting out of HCl and the formation of the corresponding substituted enol acetate. The reaction products have been hydrolyzed to aldehydes and ketones.For Communication XIII, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 7, pp. 871–873, July, 1970.