Issue 3

JTAM, Sofia, vol. 11 Issue 3 (1980)

Synthesis of Lever Mechanisms Using Linear Programming Methods

Iv. Kotchev
21 K. Marx Str., Plovdiv

A new method for approximate synthesis of lever mechanisms is developed in the paper. The linear programming theory is used. The optimal synthesis is achieved by minimizing the averagely weighted deviation over a discrete set of points. The method surpasses in many points the classical schemes of synthesis.

JTAM, Sofia, vol. 11 Issue 3 pp. 011-017 (1980)

A Dynamical Analysis of Tension Step Regulators

P. Genova
High. Inst. for Mech. and Electr. Eng., Durvenitsa

A dynamical analysis of some lever mechanisms for tension step regulators (TSR) used in practice, is made taking into account the oil media hydrodynamic resistance. Combinations of different structures of switch mechanism (SM) and spring motors (Spr M) are investigated. Conclusions concerning the highspeed action, the velocity and acceleration maximums and the effect of the hydrodynamic resistance, taking into account different combinations of SM and Str M are made with the help of lots of computer experiments. The results obtained are useful and necessary in TSR designing.

JTAM, Sofia, vol. 11 Issue 3 pp. 018-028 (1980)

Local Synthesis of Revacycle Bevel Gear Cutter

F. Litvin, V. Britski, P. Parushev
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, Geo Milev

The paper proposes a method for definition of revacycle bevel gear cutter construction parameters. This method is based on a local synthesis in the point of calculation. The local synthesis has the following characteristics: a) correlations between the self-enveloping surface curvatures are used, those surfaces being in linear and point contact; b) the envelope of the contact lines on the instrument and gear conjugate surfaces is excluded; c) a space form of the instrument cutter fixing line is used. The initial values and the parameter variation limits are given.

JTAM, Sofia, vol. 11 Issue 3 pp. 029-034 (1980)

An Approximate Method for Investigation of Waves in Fiber-Reinforced Beams

G. Popov
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8, Geo Milev

Two approximate methods for dynamic calculations of strictly oriented one-dimensional composites are proposed in the paper. The basic equations of motion in displacements are obtained by means of the Hamilton principle. Those equations create a possibility for investigation of the dispersion of trans versal waves propagating along the fibre direction. The longitudinal waves propagate without dispersion along the main directions. A displacement and phase surface stress boundary conditions are derived. Second order stiffness-for fibres and binders are introduced. The dispersion curves obtained are corn pared to some experimental data.

JTAM, Sofia, vol. 11 Issue 3 pp. 035-044 (1980)

Underground Equipment Designing with Seismic Impacts Taken into Account

N. Fotieva, N. Bulitchev
199026 Leningrad, 21 Linia, 2 Leningrad Mining Inst.

The paper investigates underground equipments under seismic impacts. The investigation is brought to the solution of two plane contact problems of the theory of elasticity in the quasistatic case.

JTAM, Sofia, vol. 11 Issue 3 pp. 045-049 (1980)

A Solution of Boundary Problems of Continuum Mechanics by the Method of P-transformations

A. Gluschenko, P. Bezdetni

P-transformation numerical methods for the solution of continuum mechanics problems are analysed in the paper. Those problems emerge from the theory of filtration, theory of elasticity, mechanics of hydrotechnical devices etc.

JTAM, Sofia, vol. 11 Issue 3 pp. 050-053 (1980)

A Numerical Solution of Nonstationary Processes in Pressure Systems by Means of Fast Oscillation Integral Equations

R. Petkov
Inst. of Water Problems, Bulg. Acad. Sci, Bl4, Geo Milev

The equations of fast oscillations (hydraulic shock) are solved numerically in the paper. The solutions are obtained with the help of the laws of momentum conservation and mass conservation. The equations are given in an integral form and with nonlinear boundary conditions. A numerical method stablity estimation is given and the method convergency is proved taking into account the initial and the boundary conditions.

JTAM, Sofia, vol. 11 Issue 3 pp. 054-060 (1980)

On the Structure of a Collisionless Shock Wave with the Magnetic Viscousity Taken into Account. II

M. Kartalev
Inst. of Mech. and Biomech., Bulg. Acad. Sci., Bl. 8 Geo Milev

The structure problem of a collisionless shock wave in plasma with anisotropic pressure is investigated in one-dimensional stationary case. The dissipation is recognized by introducing a finite conductivity of electricity. A longitudinal entropy conservation is supposed. The solution existence and uniqueness is investigated for the system created. This solution is of the type of the shock wave structure. The known Jerrnain proof of fast shock wave existence and uniqueness is generalized. This proof concerns waves in the isotropic magnetic hydrodynamics. However principal difficulties appear connected with the thermodynamic function complication and in particular with the free energy complication. In the same time the mutual disposition of the characteristic velocities is not one-valued. The structure existence is proved with definite restrictions taken into account. The result is valid for an arbitrary correlation between the magnetic viscousity and the medium parameters. The actual type of such a correlation is not discussed in the paper.

JTAM, Sofia, vol. 11 Issue 3 pp. 061-069 (1980)

A Theoretical Model of a Potential Flow in an Arbitrary Axis – Symmetric Channel

K. Varsanov, A. Haimov
Inst. of Nav. Hydromech., Varna

It is proposed a model and a numerical algorism for the axis – symmetric potential flow investigation. The flow tube is with an arbitrary generatrix and with centrally located body. The tube and body contours are outlined by a system of vortex peculiarities, while the infinity boundary conditions are provided by discs from sources, closing the outside tube cross-sections. Numerical results and comparisons to known solutions for constant radius tubes are shown. The results are obtained with a satisfactory accuracy with a little computer time expence, in a wide range of geometry parameter variation. A number of the method applications is given.

JTAM, Sofia, vol. 11 Issue 3 pp. 070-075 (1980)

A Criterion for Oil Product Cylindric Container Stability

S. Kisliakov
High. Inst. for Arch. and Civ. Eng., 1 Chr. Smirnenski Blvd., Sofia

There are proposed three necessary criteria for stability control of the containers mentioned. Those criteria give an account of the danger of buckling due to the couple stresses as well as to the the normal stresses as a result of bending. Such an approach is different from that known from literature.

JTAM, Sofia, vol. 11 Issue 3 pp. 076-080 (1980)

Some Investigation of Thin-walled Glass Plastic Roof Structures

L. Hadjikov, Chr. Christov
Inst. of Mech. and Biomech., Bulg. Acad. of Sci., Bl. 8, Geo Milev

The paper gives a short review of the thin-walled space structures of shell type, designed in the Institute of mechanics and biomechanics – Bulgarian Academy of Sciences. Significant experimental results and interesting geometrical investigations are given. Some more important future investigations are noted.

JTAM, Sofia, vol. 11 Issue 3 pp. 081-093 (1980)

Some Investigations of an Elastically Supported Circular Ring Stability

V. Drumev
High. Inst. for Arch and Civ. Eng., 1 Chr. Smirnenski Blvd., Sofia

The stability of the ring mentioned is investigated in the paper. The loading is hydrostatic. The ring is supported by an elastic support of a most general type. This support resists against the radial and tangential displacements and against the ring cross rotations. It is described by three corresponding coefficients. The solution is obtained by an energy method. The elastic support component effect on the critical load value is investigated. The possibility of solution simplification is analyzed as well.

JTAM, Sofia, vol. 11 Issue 3 pp. 094-101 (1980)

Transversal Deformation Coefficient Variation in the Case of Elastic, Plastic and Elastic-Plastic Deformations

S. Mandjakov
High. Inst. for Mech. and Electr. Eng., Durvenitsa

The variation of the coefficient mentioned is investigated. It is given an account of the geometrical changes of the deformable body elementary parallelepipeds. The corresponding formulas, concerning that coefficient, are derived. Different cases of elastic-plastic deformation are taken into account.

JTAM, Sofia, vol. 11 Issue 3 pp. 102-107 (1980)