Issue 1

JTAM, Sofia, vol. 12 Issue 1 (1981)

On the Multiple Differentiation of y-Composite and y-Implicit Functions, Related to the Analysis and Synthesis of Mechanisms

K. Enčev
High. Inst. of Agr. Eng., Russe


It is built a method for multiple differentiating of y-composite and y-implicit functions, i.e. functions characterised by y-repetition of partial differentials. A theorem is proved, which helps the obtaining of working formulas for calculation of the successive differentials of the fuuctions discussed.

JTAM, Sofia, vol. 12 Issue 1 pp. 013-019 (1981)


Synthesis of Optimal Transmission Functions by Means of Linear Programming Methods

Iv. Kočev
K. Marx Str. 21, Plovdiv

The problem of the synthesis of the dynamical optimal laws of motion has been formulated as a problem of the linear programming. This makes possible the synthesis of laws, subjected to an arbitrary number of restrictions and of naturaly defined optimization criteria. The method makes possible the solving of new optimization problems.

JTAM, Sofia, vol. 12 Issue 1 pp. 020-025 (1981)


Synthesis and Analysis of a Conic Gear, Cut by Means of the Continuous Disc-Broaching

F. Litvin, V. Britzkij, P. Parušev

The paper proposes a method for the analysis of a conic gear cut by means of the continuous disc-broaching ("Revacycle"). The following equations are derived: a) equations of the criteria defining the qualities of the gear surfaces in the working zone, cut by means of a cutterbroach: b) equation of the criteria of gearing quality ; It is investigated the effected of the parameters variated on the quality criteria and the constructive parameters of the cutterbroach. A numerical example of the gear synthesis is given.

JTAM, Sofia, vol. 12 Issue 1 pp. 026-030 (1981)


On the Application of Dynamic Stability Conditions of Periodic Oscillations in Mechanisms with Elastically Transmission Shaft

Nguen Van Khang
Hanoy, Vietnam

The paper deals with the problem of the application of the small parameter method to the definition of the dynamic stability conditions and of the periodic oscillations of elastic transmission shaft mechanisms.

JTAM, Sofia, vol. 12 Issue 1 pp. 031-039 (1981)


A Calculation of the Resistance Coefficient of Double Blade-Grid

V. Ljubenov, T. Čakârov
High. Inst. of Mech. and Electr. Eng., Durvenica

The paper proposes an evaluation of the energy properties of a double blade-grid. This evaluation is to be made by analyzing of the velocity distributions along the blade surfaces and by calculation of the resistance coefficient as well. A new approach to the resistance coefficient calculation is given using a suitable method from the theory of the boundary layer.

JTAM, Sofia, vol. 12 Issue 1 pp. 040-042 (1981)


Some Investigations of the Water Particle Kinematics in the Case of Three-Dimensional Casual Motion

P. Gradinarov
High. Inst. of Mech. and Electr., Eng., Varna

A three-dimensional casual motion with respect to the spectral theory is investigatad. The substantial (Lagrange's) approach is used. There are given the equations of the water particle motion. They are simplified with respect to the assumption that the motion is a thin-stripped casual process (in the frequency region).

JTAM, Sofia, vol. 12 Issue 1 pp. 043-048 (1981)


On a Class of Differential Equation Sulution, the Equations Describing a Fixed Process in a Medium with Variable Parameters

A. Vitanov
High. Inst. of Chem. Ind., Šumen

There is investigated the solution of a special type of a partial differential equation which for example is obtained in the process of investigation of water filtration through a layer with a given water conductivity.

JTAM, Sofia, vol. 12 Issue 1 pp. 049-057 (1981)


Plane Contact Waves in a Hyper-Elastic Incompressible Material

L. Vâtkov
High. Inst. of Agr. Eng., Russe

Using the mathematical methods of the quazilinear hyperbolic systems the author investigates what is the type of the material, in which with respect to the deformation potential there are not formed shock waves.

JTAM, Sofia, vol. 12 Issue 1 pp. 058-062 (1981)


An Experimental Investigation of Wave Dispersion, the Waves Propagating in Thread-Reinforced Composites

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

There is investigated the dispersion of harmonic waves in glass-polyester composite by means of high frequency impulse methods. Relations between the velocity and the frequency of longitudinal and transversal waves are obtained. There are determined the static and the dynamic elastic moduli of the composite. There are given data concerning the shock wave front propagation in a long previously tensed glass polyester rod The results of the calculations are compared to the experimental registration of the longitudinal waves which is achieved for a first time in Bulgaria.

JTAM, Sofia, vol. 12 Issue 1 pp. 063-068 (1981)


On the Problem of the Identification of Models According to the Data from the Destructiveless Wave Method

A. Baltov, Ir. Nikolova
Inst. of Mech. and Biomech.. Bulg. Acad. Sci., Bl. 8, Geo Milev

The paper proposes for a first time a way of creating a method which makes possible the definition of a suitable mechanical-mathematical model describing properties of materials tested by means of the destructiveless wave method. This method is based on a suitable comparison between the solutions of series of initial-boundary wave problems. The solutions are performed according to the finite system method. The experimental data are obtained by using the destructiveless wave method. The ideas proposed are illustrated by examples from the group of inelastic models of Maxwell's type.

JTAM, Sofia, vol. 12 Issue 1 pp. 069-075 (1981)


On the Dynamic Stability of a Circular Ring on an Elastic Foundation

U. Drumev
High. Inst. of Arch. and Civ. Eng., 1 Hr. Smirnenski, Sofia

A thin elastic homogeneous circular ring on an elastic Winkler foundation of a general type is considered. The foundation resists to the normal and tangential displacements and to the rotations of the cross-sections, when the ring is bent in its plane, and therefore it is represented by three appropriate foundation moduli. The dynamic stability of the ring in its plane under a uniform, normal to the central-line directed loading (fluid-pressure loading) is investigated. The casses of the loading vhich is suddenly applied and afterwards remains constant, and a periodic loading of the form q = qo + qtcosθt are solved. The influence of the elastic foundation on the dynamic stability is discussed.

JTAM, Sofia, vol. 12 Issue 1 pp. 076-083 (1981)


A Static Investigation of a Sloping H. P. Shell on a Rectangular Foundation

A. Tepavičarov, G. Gospodinov, D. Ljuckanov
High. Inst. for Arch. and Civ. Eng., 1 Hr. Smirnenski Blvd, Sofia

There is analyzed the problem of the investigation of the stress-strain state of a sloping shell with constant thickness on a rectangular base with an arbitrary outer loading taken into account and an arbitrary temperature field considered. The differential equations for the displacements are integrated by means of the double trigonometric series method. There is used M. Todorov's approach to the integration of the differential equations by means of infinite series. The method thus created is very simple and can be applied to problems with arbitrary boundary conditions concerned. It is discussed the important practical case of a shell supported on ideal diaphragms by means of joints.

JTAM, Sofia, vol. 12 Issue 1 pp. 084-094 (1981)


The Effect of Intensive Stress Waves on the Physical-Mechanical Properties of Metals

F. Dushek, St. Vodeničarov
Inst. of Met. Res. and Met. Techn. Capaev Blvd 53, Sofia

The paper investigates the effect of stress waves on the metal physical-mechanical properties. It is investigated the microstructural dislocation mechanism as well.

JTAM, Sofia, vol. 12 Issue 1 pp. 095- (1981)