Issue 3
JTAM, Sofia, vol. 10 Issue 3 (1979)

Dynamics of a Machine Aggregate with Rigid Links and Hooke's Coupling Concerning the Aggregate-Motor Interaction

S. Butchvarov, V. Pandov
High. Inst. for Mech. and Electr. Eng. “V. I. Lenin", Durvenitsa


The stationary auto-oscillation processes in a machine aggregate with single Hooke's coupling as an electro-mechanical system have been examined in the paper. The dynamical properties of the drive, realized by a direct current motor with independent field and non-linear character of the process load have been regarded. The elasticity of the links has been neglected. A solution to second approach for the motor movements and the electromagnetic resonance frequencies by the method of the small parameter have been obtained. The law of the driving moment has been defined too.

JTAM, Sofia, vol. 10 Issue 3 pp. 013-019 (1979)

On the Multiplex Differentiating of x-Complex and x-Implicit Functions, Concerning the Analysis and Synthesis of Mechanisms

K. Entchev
High. Inst. for Agr. Eng. – Russe

A method for multiplex differentiating of the functions mentioned has been constructed. A theorem, used in the obtaining of the successive derivative calculation working formulas, has been proved.

JTAM, Sofia, vol. 10 Issue 3 pp. 020-029 (1979)
The Effect of Gravitational, Aerodynamic, Magnetic and Constant Moments on the Relative Equilibrium of a Satellite-Gyrostate System Running along a Circular Orbit

P. Atanasova
Inst. of Mech. and Biomech., Bl. 8. Geo Milev str

The relative equilibrium positions of a satellite with rotors their mass center running along a circular orbit have been defined. The effect of the moments mentioned on the satellite has been taken into account.

JTAM, Sofia, vol. 10 Issue 3 pp. 030-036 (1979)
An Experimental Investigation of Double Curvature Glass-Plastic Slooping Shells on a Rectangular Base and with a Temperature Effect Taken into Account

Ngo The Fong
High. Inst. of Arch. and Civ. Eng., 1 Hr. Smirnensky Blvd

The paper concerns an experimental investigation of the shells mentioned with the influence of different constant temperatures taken into account. In the same time a cyclically changing temperature has been considered. The experimental data have been processed, taking into account some theoretical assumptions in the author's previous papers.

JTAM, Sofia, vol. 10 Issue 3 pp. 037-046 (1979)
Shell Nonclassic Theory and Its Applications

V. Bajenov, V. Guljaev, P. Lizunov
Leningrad, 10 Linia, d. 33, Mathematical Faculty

Some particularized equations of nonthin shell theory have been proposed, the shell thickness being variable. The equations have been obtained as a result of thermoforce equilibrium equation projecting with a deformable medium element taken into account. The relations obtained lack the disadvantages of the Kirkhov–Luve hypothesis application. The lack of simplifying propositions, concerning the distribution character of the functions needed, enables the analyzing of the equilibrium stability and the postcritical behaviour of the thick wall shells on the ground of Newton-Kantorovitch one step method modification. The problem of the thermal shock has been analysed as well. The thermal boundary layer has been separated and the thermal field evolution has been investigated. The particularized equation hyperbolicity makes possible the solving of shell wave problems. The investigations have been carried out until reaching some numerical results.

JTAM, Sofia, vol. 10 Issue 3 pp. 047-051 (1979)
On the Inhomogeneity Problem in Micropolar Elasticity

K.Z. Markov
Sofia 1113, Inst. of Mech. and Biomech., Bl. 8, Geo Milev str

The problem of determining the stress and couple-stress fields within a single micropolar inhomogeneity, immersed into an unbounded micropolar matrix loaded at infinity, has been discussed A system of integral equations has been deliverd for the problem and an iterative process, solving the system, has been proposed. In the case of a spherical inhomogeneity, it is shown that the first step of the process coincides with the approximate solution, found by means of Eshelby's method.

JTAM, Sofia, vol. 10 Issue 3 pp. 052-059 (1979), [Full Article]

On the Exploiting of a Two Layered Model in the Investigation of the Relaxation of a Body in a Liquid Medium and with Lineary-Hereditary Reology Properties

K. Popov, Kl. Hadjov
High. Inst. of Chem. Eng., Durvenitsa

The investigation concerns a material which reology properties in a dry state are described by means of the linear integral equations of Voltera. If it could be assumed that the liquid pentration has a frontal character and that there is a clear distinction between dry and saturated layer in the body, then the body mechanical properties should be constant through the time. The model proposed and the sorption curve have been used in the force relaxation calculation.

JTAM, Sofia, vol. 10 Issue 3 pp. 060-064 (1979)
Asymptotical Study of Convective Heat Transfer from a Vertical Plate in a Viscous Incompressible Fluid

P. Kalitsova-Kurteva, Z. Zaprianov
Inst. of Mech. and Biomech. Bl. 8, Geo Milev str.

An analysis of the free convective laminar flow of an incompressible, viscous fluid past an infinite vertically moving plate, has been carried out. The velocity and the temperature of the plate are proportional to the power of the time. We are concerned with the case of large Raynolds number and small intervals of time. An exact solution was constructed when viscous dissipation was neglected. In the case when viscous dissipation takes place, an approximate solution has been found. A comparison between numerical and approximate analytical solutions is given.

JTAM, Sofia, vol. 10 Issue 3 pp. 065-075 (1979)
On the Calculation of Gas-Thermo-Dynamical Processes in Chemical Reactor

I. Jeleva, G. Mahviladze, Hr. Hristov
Inst. of Mech. and Biomech., Bl. 8, Geo Milev str.

The problem of flat chemical reactor nonstationary flow modelling has been discussed in the paper. The problem has been formulated on the ground of the full Navie-Stokes equations, concerning viscous compressible thermocon-ducting gas flow. Those equations have been completed by the equations of concentration of one of the chemical components. A solution has been obtained with the help of a numerical algorithm, proposed by G. Mahviladze and S. B. Shterbak.

JTAM, Sofia, vol. 10 Issue 3 pp. 076-085 (1979)
Unsteady Magnetohydrodynamic Channel Flow of a Dusty Rivlin-Ericksen Fluid

K. Singh, P. Ram
Inst. of Technology, Baranassy – 221005, India

In the course of the investigation it has been observed that the velocity of the fluid particles is greater than the velocity of the dust particles nearer to the axis of the channel. This difference is due to the fact that the inertia of the dust particles is more than the inertia of the liquid particles. If the masses of the dust particles are small, their influence on the fluid flow is reduced and in the limit as m → 0 the fluid becomes ordinary viscoelastic. When the transverse magnetic field is not applied we get the solution of ordinary viscoelastic fluid through channel.

JTAM, Sofia, vol. 10 Issue 3 pp. 086-093 (1979), [Full Article]

Formulation of the Problem of Optimal Longitudinal Vibration

A. Baltov
Inst. of Mech. and Biomech., Bl. 8, Geo Milev str.

It has been illustrated in the paper, that the finite system method proposed can be succesfully applied to the solving of the problems mentioned, with the rod material being elastic, plastic or viscous. The Pontriagin principle of maximum has been used and two bar vibration problems, i.e. true and fictitious, have been formulated. An algorithm, solving the optimal problems treated is given.

JTAM, Sofia, vol. 10 Issue 3 pp. 094-100 (1979)
Analysis of Previously Tensed Reinforced Concrete Thin Wall Bar Stability

St. Pamuktchiev
High. Inst. of Arch. and Civ. Eng., 1 Hr. Smirnensky Blvd.

The paper deals with reinforced concrete thin wall bars. The investigation has been performed on the ground of prof. V. Z. Vlasov's theory, concerning thin wall bars. The previously tensed bars have great openings and highly diminished thickness. Thus, it is necessary to increase their general stiffness and stability. The influence of the transversal bonds upon the value of the critical force has been noted in the paper. Some methods of increasing the critical force have been mentioned.

JTAM, Sofia, vol. 10 Issue 3 pp. 101-108 (1979)
Stability of a Vicso-Elastic Bar in the Process of Vibrocreep

L. Hadjikov, P. Lasarov, P. Bekjarova
Inst. of Mech. and Biomech. Bl. 8, Geo Milev str.

The paper proposes a theoretical solution of critical time value defining, when periodically loaded and nonsymmetrically fixed bar is concerned. The solution is based on the Maxwell-Gurevitch-Rabinovitch modified nonlinear generalized equation. An algorithm, solving the nonlinear system of integral-differential equations, is proposed.

JTAM, Sofia, vol. 10 Issue 3 pp. 109-114 (1979)
On the Elliptic Cylindrical Shell Vibration

M. Kozarov, K. Mladenov
High. Inst. of Arch. and Civ. Eng., 1 Hr, Smirnensky Blvd.

The problem of elliptic shell vibration has been analysed in the paper. The solving has been performed on the ground of the equations of V. Z. Vlasov. Some own oscillation frequency expressions have been found. A computer programme has been used. The results are represented graphically. The investigations show that the shell oscillation frequency is practically equal to that of a round cylindrical shell, if both shell cross circumferences are equal.

JTAM, Sofia, vol. 10 Issue 3 pp. 115-123 (1979)