Properties of fiberglass-plastics reinforced with high-modulus fibers

The question of reinforcement of unidirectional fiberglass-plastic with boron or carbon fibers is considered. Static fatigue curves for the Poisson coefficient and the elastic modulus as functions of the volume content of the glass and the high-modulus fibers have been constructed. The theoretical dependences are compared with the experimental data.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Moscow. Translated from Mekhabika Polimerov, No. 1, pp. 68–74, January–February, 1972.     

Failure of unidirectional composite materials under axial compression

Conclusions It follows from the above-cited results that the ultimate compressive strength of unidirectional composite materials can be determined rather accurately and the character of the failure predicted when the three dimensional linearized theory of the stability of deformable solids is used. The development of similar theories for the case of fibrous materials with a large filler concentration (allowance for the mutual effect of fibers during stability loss) during brittle failure, and also for all aspects of the theory under nonbrittle failure (temperature and long-time strength, strength under plastic deformations, etc.), is a pervasively on-going problem.Paper presented at the Second Soviet-American Symposium on the Problem Failure of Composite Materials (Bethlehem, Pa., USA, March, 1981).Translated from Mekhanika Kompozitnykh Materialov, No. 3, pp. 417–425, May–June, 1982.     

Temperature fields in laminar anisotropic shells

A numerical solution of the nonlinear heat-conduction problem is obtained for laminar anisotropic shells with temperature-dependent physicomechanical properties.Translated from Matematicheskie Metody i Fiziko-mekhanicheskie Polya, No. 26, pp. 98–101, 1987.     

Wave propagation in laminar models of cracked media

Wave propagation in laminar models of cracked media is investigated. Particularly noteworthy is the low-velocity wave, which cannot be explained within the framework of a single elasticity theory.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 173, pp. 123–133, 1988.     

Temperature distribution in a laminar circular jet

The effect of frictional heat on the temperature distribution in a laminar circular jet has been studied. It is found from the analysis and the graphs that as the Prandtl number decreases from unity the overall temperature difference near the axis of the jet increases but as we move away from the axis it goes on decreasing. The reverse phenomenon happens in the case of increasing Prandtl number.     

Thermal expansion coefficients of laminar composites

The conclusion of [1], according to which the coefficient of linear expansion of a laminar composite in a direction orthogonal to the laminations may exceed the greater of the coefficients of linear expansion of the components, has been experimentally verified. The experiments were performed on laminated metal-plastics composed of alternating layers of thin sheet steel and epoxy-phenolic resin. The coefficients of linear expansion were determined in a direction normal to the laminations at temperatures of from 20 to 100°C and various component ratios. The experimental and theoretical results are compared.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 3, pp. 567–568, May–June, 1969.     

Numerical studies of laminar flow in ducts and pipes

In part I a method is introduced for the numerical solution of swirling axisymmetric laminar flow situations. Consideration is given to finite difference formulation, boundary condition implementation, iterative solution strategies and pressure calculation. Part II is devoted to the application of the method to non-swirling flow problems. Some of these problems are well covered in the literature whilst others are new. Swirling flows are considered in Part III. In particular, details of separation and vortex breakdown induced by swirl are discussed. All results are supplemented by a selection of contour plots to indicate the nature of the flows predicted.     

Theoretical model of laminar flow in tubes in rolling motion

The theoretical model of laminar flow in tubes in rolling motion is established. The velocity and temperature correlations are derived, and the frictional resistance coefficient and Nusselt number are also obtained. The oscillation of parameters is induced by the tangential force due to rolling motion. The effect of centrifugal and Coriolis forces on the flow is negligible. The tangential force does not effect on the average parameters. The oscillating amplitude of Nusselt number increase with the Prandtl number increasing. Both the oscillating amplitudes of frictional resistance coefficient and Nusselt number increase with the rolling frequency increasing.     

Temperature distribution in a laminar plane wall jet

In the present note the temperature distribution in a laminar plane wall jet has been studied. It is found that a similarity solution of the energy equation exists. The resulting ordinary differential equation is reduced to a hypergeometric equation by a suitable transformation of the similarity variable and the solution, for arbitrary values of the Prandtl number, is obtained. It is concluded that the heat transfer at the wall at a given section and the product of volume and heat-flux through any cross-section of the boundary layer increase with the increase in the value of Prandtl number respectively.     

Rectilinear laminar flow of a visco-elastic fluid

Zusammenfassung Eine inkompressible viskoelastische Flüssigkeit fliesst zwischen zwei parallelen, starren, unendlichen Wänden. Es wird unter der Voraussetzung, dass die eine Wand fest ist und die andere sich mit einer exponentiell abklingenden Geschwindigkeit bewegt, das zur Aufrechterhaltung einer speziellen laminaren Strömung nötige Kraftfeld bestimmt.     

Modelling the attenuation of laminar fluid transients in piping systems

The damping of laminar fluid transients in piping systems is studied numerically using a two-dimensional water hammer model. The numerical scheme is based on the classical fourth order Runge–Kutta method for time integration and central difference expressions for the spatial terms. The results of the present method show that the damping of transients in piping systems is governed by a non-dimensional parameter representing the ratio of the Joukowsky pressure force to the viscous force. In terms of time scales, this non-dimensional parameter represents the ratio of the viscous diffusion time scale to the pipe period. For small values of this parameter, the damping of the fluid transient becomes more pronounced while for large values, the fluid transient is subjected to insignificant damping. Moreover, the non-dimensional parameter is shown to influence other important transient phenomena such as line packing, instantaneous wall shear stress values and the Richardson annular effect.