Issue 4

JTAM, Sofia, vol. 9 Issue 4 (1978)

Equilibrium Orientations of a Gyrostate Satelite – on a Circular Orbit with Inner Motions Fixed

A. Antchev, L. Lilov
Inst. of Mech. and Biomech. Bulg. Acad. Sci., Kv. Geo Milev, Bl. 8, Sofia


The equilibrium orientations of a stelite-gyrostate system have been found with a central power field taken into account and a fixed constant inner kinetic moment concerned.

JTAM, Sofia, vol. 9 Issue 4 pp. 009-015 (1978)


An Infiniite Plane with Holes Described According to the Couple Stress Theoryof Elasticity

Sh. Dukova
High. Inst. for Arch. and Civ. Eng., Khr. Smirnensky Blvd. 1, Sofia

A solution of a problem previously solved by means of the classic theory of elasticity is given in the paper. The complex potentials are defined by the Mushelishvilly method known from the classic theory of elasticity. More than that they are not expressed by means of infinite series, as it is usual, but their values for a series of points on the boundary are defined by means of sequential approximations. The unknown coefficients of the function, which is a solution of the Helmholtz equation, are found with the help of the second equation of the boundary problem, which is satisfied in the same points. The numerical results show that when small holes are concerned and the couple stress theory is applied the stresses obtained are much greater than these, obtained by means of the classic theory.

JTAM, Sofia, vol. 9 Issue 4 pp. 016-019 (1978)


Nonstationary Boundary Layer with Round Cylinder Inclined Flow Around TakenInto Account

Z. Zaprianov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Kv. Geo Milev, Bl. 8

The problem of spatial nonstationary boundary layer definition with round cylinder inclined flow around taken into account, based on the “principle of in dependence", is discussed as a combination between two plane problems – one along a direction perpendicular to the axis of the cylinder and the other one – along its generatrix. A solution of the second problem has been obtained by the method of matched asymptotic expansions. The exactness obtained is of second order.

JTAM, Sofia, vol. 9 Issue 4 pp. 020-024 (1978)


Heat Exchange in a Fully Developed Flow of a Viscous Noncompressible Fluid in a Toroidal Tube

Z. Zaprianov, E. Toshev, Khr. Khristov
Inst. of Mech. and Biomech. Bulg. Acad. Sci., Bl. 8,Kv.Geo Milev

A heat exchange problem, concerning a fully developed flow of a viscous noncompressible fluid in a toroidal tube, is solved in the paper. A numerical solution of the temperature distribution concerning 0,005-2060 Prandtl numbers and 100-2000 Dean numbers has been obtained, while the velocity profiles have been considered given. The peripheral averaged Nusselt number has been calculated and it has been described as a function of Dean number and Prandtl number.

JTAM, Sofia, vol. 9 Issue 4 pp. 025-030 (1978)


Motion of a Liquid in a Round Cylindric Area with a Complex Configuration

V. Dzhupanov, P. Dineva, N. Trendafilov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Kv. Geo Milev, Bl. 8

A thick wall cylinder has been coaxially inserted in a cylindric container, containing infinite medium. A wave producer has been attached to the center of the container bottom. The wave produced has been moving along the axes of the cylinders. The velocity potentials of the infinite medium have been de fined as well as the acoustic energy scattering, caused by the diffraction of the edges of the cylinder inserted. The results obtained may be applied to noisekiller designing.

JTAM, Sofia, vol. 9 Issue 4 pp. 031-042 (1978)


Postcritical Deformations of Orthotropic Shells with Axial Pressure Taken into Account

V. Babenko, J. Ivanova
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Kv. Geo Milev, Bl. 8

The paper analyses the postcritical oscillations in thin orthotropic shells, which are freely supported, have average length and undergo axial pressure. The geometrical approach of Pogorelov has been applied to shell designing.

JTAM, Sofia, vol. 9 Issue 4 pp. 043-051 (1978)


A Theoretical Analysis of Cylindric Shell Stability in the Presence of Vibro Creep

L. Hadjikov, K. Simeonova
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Kv. Geo Milev, Bl. 8., Sofia

The paper analyses theoretically the cylindric shell stability, the shell loaded by means of axial periodic load, described by the following equations: Pdyn = Pstat + Pasinωtσdyn = σstat + σasinωt. An equation describing the precritical shell state has been derived, the necessary conditions having been counted. A system of partial defferential equations has been presented. A solution of the critical time definition problem will be given, based on the proposed system.

JTAM, Sofia, vol. 9 Issue 4 pp. 052-055 (1978)


A Sloping Spherical Shell Designing Method with a Rectangular Base Concerned

A. Tepavitcharov
High. Inst. of Arch. And Civ. Eng., Khr. Smirnensky Blvd. 1, Sofia

The presented paper shows that approximate solutions in a closed form may be constructed. This solution may be used for designing the above mentioned shells. Those approximate formulae could be processed until an exactness needed could be obtained.

JTAM, Sofia, vol. 9 Issue 4 pp. 056- (1978)