Issue 4

JTAM, Sofia, vol. 12 Issue 4 (1981)

Precision Analysis of Manipulative Systems

L. Lilov, P. Parushev, B. Bekiarov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, G. Milev

The following work considers arbitrary non-deflecting manipulative systems with kinematical pairs of 5 class. Compact analitic expressions for determining the errors in positioning and orientation of an arbitrary orthonormal coordinate system, stationary connected with the catch up, are obtained for such systems. The created mathematical model takes account of all essential parameters which affect the errors of positioning and orientation, such as: slackenings in kinematical pairs, errors in realisation of the generalized coordinates and errors in realisation of constant linear and geometric dimensions.

JTAM, Sofia, vol. 12 Issue 4 pp. 011-019 (1981)

Stability of the Relative Equilibrium of a Satelite-Gyrostat, Moving on a Circular Orbit

P. Atanasova
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, G. Milev

The stability of equilibrium orientations (obtained in I) of a satelitegyrostat with uniformly circulingrotors, movingonanequatorial orbit and affected by the actions of gravity, earodinamic and magnetic moments, is examined in the work. Sufficient conditions for stability are obtained using the direct Lapunov method and by means of generalized energy integral, for the cases when centre of pressure of aerodinamical resistance is fixed in the satelite during the whole time, or when the coordinates are the first derivatives to the directirial cosines of the tangent to the orbit of the main central innert axes of the gyrostat, from a function, decomposable inseries of the powers of these cosines. Examples are given.

JTAM, Sofia, vol. 12 Issue 4 pp. 020-028 (1981)

Stress-Strain State of Compound and Console Bars

P. Marinov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, G. Milev

In searching criterions for evaluation of the stress-strain state of plane systems of compound bars, one may simplify the problem considering the stress-strain stata of the systems under extreme boundary conditions. A system of two linear differential equations with constant coefficients is solved inder two types of boundary conditions, which answers a fixed low end a free upper end of a plane system of two compound bars. The conclusions are illustrated by an example from practice.

JTAM, Sofia, vol. 12 Issue 4 pp. 029-037 (1981)

Thermocapillary Convection of uncompressible Fluid with Free Surface

J. Kojuharova, S. Slavchev
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, G. Milev

Finding automodel solutions of the equations of thermocapillary-convection of uncompressible fluid is possible under some conditions. Those conditions are examined in the work. The free surface fills the semi-space. Two classes of solutions answering deffinite laws of distribution of temperature on the fluid surface are obtained. The picture of the corresponding flow and its temperature field are presented with diagrams for different of Prandtl coefficient.

JTAM, Sofia, vol. 12 Issue 4 pp. 038-045 (1981)

Nonisothermal Flow of High-Viscous Fluids in Tubes

I. Shnaider

Problems of a flow of a high-viscous fluid in a tube with a circle section are considered in the paper, when there is a relation between the velocity field and the temperature one. The equations describing the process are a system of nonlinear differential equations solved in terms of iteration and differential methods. The obtained results are of interest for some technical problems such as: treatment of polymer materials, capillary viscosymetry of high-viscous fluids.

JTAM, Sofia, vol. 12 Issue 4 pp. 046-050 (1981)

Application of the Method of Finite Systems in Structure Dynamics

A. Baltov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, G. Milev

The proposed by the autor method of finite systems is applied in this work to examine the dynamical conduct of structure elements of the type of bar structures, thin-walled plates and inclined shells. The material of the structure elements may possess various mechanical properties-elastic, viscous, plastic.

JTAM, Sofia, vol. 12 Issue 4 pp. 051-064 (1981)

About the Plastic Bending of Beams with Constant Cross Sections

S. Nedelchev, S. Mangakov, N. Gospodinov
Inst. for Mech. and El. Eng., Durvenitsa

Formulas about the stress-strain state of beams with constant cross section, subjected to clear bending, with plastic properties are obtained in the paper. The examination is carried out in the framework of the plastic deformation theory, using the power stress-train connection.

JTAM, Sofia, vol. 12 Issue 4 pp. 065- (1981)