Issue 2
JTAM, Sofia, vol. 15 Issue 2 (1984)

Structural-Kinematic Analysis of Spatial Mechanisms

L. Lilov, V. Atanassov
Inst. Mech. Biomech., Bulg. Ac. Sci., Bl. 8 Geo Milev


A general procedure for the determination of the degree of mobility of arbitrary mechanisms is analysed. However, to make the procedure applicable, the authors have used Lilov's formal apparatus for the determination of the equations of constraints and the Jakobian of the system. The degree of mobility of Bennett's constrained mechanisms have been determined as an example. Dimensional relations for the degree realisation have been obtained as well. A method for the determination of special positions of an arbitrary mechanism is developed, whereas special positions are taken to be these, for which to an infinitesimal displacement of the input link correspond several infinitesimal displacements of the output one. In this respect, criterion for an optimal choice of the input link is proposed.

JTAM, Sofia, vol. 15 Issue 2 pp. 011-022 (1984)

Dynamical Equations of Motion of Manipulation Systems with Taking into Account the Link Elastic Properties

M. Lorer
Inst. Mech. Biomech., Bulg. Acad. Sci., Bl. 8 Geo Milev

The paper treats the derivation of the complete equations of motion of manipulation systems, with taking into account the link elastic properties. The equations may he employed for the determination of the basic parameters of the oscillation process. Moreover, positioning and control, and the effect of the elastic deformation on the variation of the manipulator generalized coordinates, may be estimated.

JTAM, Sofia, vol. 15 Issue 2 pp. 023-031 (1984)
A Generalized Method for Kinematic Analysis and Synthesis of Plane Mechanisms

V. Galabov
High. Inst. Electr. Mech. Eng., Darvenitsa

The kinematic equivalence of plane mechanisms is revealed, and by means of the apparatus of kinematic geometry, a generalized approach is proposed and a general method for the analysis and synthesis is worked out. The method turns to be efficient not only when used for type-dimensional synthesis, determining simultaneously the kinematic schemes of four types of plane mechanisms, but also for the analysis and synthesis of various types of plane mechanisms.

JTAM, Sofia, vol. 15 Issue 2 pp. 032-043 (1984), [Full Article]

A Transversely Isotropic Plate Indented by a Flat Annular Rigid Stamp Overlaying an Elastic Foundation

M. Lal
School of Studies in Mathematics, Jiwaji University Gwalior 7-44011, India

The present paper attempts to solve the problem of indenting a transversely isotropic plate by a flat annular rigid stamp, overlaying an elastic foundation. However, the normal displacement is specified inside an annular area a ≤ r ≤ b, the normal stress is zero in the region 0 ≤ r ≤a, r < b, and the shear stress is zero on the upper face z = —h of the elastic layer. The continuity of the normal and shear stress is assumed at the interface (z=0) between the elastic layer and the elastic foundation, having different elastic constant. The problem is reduced to the solution of an infinite set of simultaneous equations. Radial distributions of stress, displacement and total compressive load are presented graphically.

JTAM, Sofia, vol. 15 Issue 2 pp. 044-052 (1984), [Full Article]

Numerical Solution of the Direct and Inverse Problem of the Engineering Seismology Considering Damping in Soil

K. Ishtev, F. Filipov, P. Dineva, L. Hadjikov
Inst. Mech. Bioniech., Bulg. Acad. Sci., Bl. 8 Geo Milev

The paper presents a numerical solution of the problem. Results for both a layered elastic medium and layered medium with damping are compared. Comparison to some other experimental results is made as well. Physical interpretations of the phenomenon are revealed by introducing a theoretical summary damping coefficient. An estimation of the prospects of application to underground facilities under seismic impacts is performed.

JTAM, Sofia, vol. 15 Issue 2 pp. 053-058 (1984)
Analytical Determination of the Surface Wave Group Velocities for a Specific Building Sight

I. Paskaleva, G. Georgiev, S. Simeonov
CLSMSI, Bulg. Acad. Sci., Bl. 3 Geo Milev

A number of problems of the seismic mechanics demand solution of the direct problem, i.e. the analytical determination of the group velocities of Love's and Rayleigh's waves. What is obtained in the paper is a numerical solution of the problem. Moreover, the Dirack impulse under dispersion is determined and several modes are taken into account. The group velocity – multilayered structure relation is given and the effect of the sediment subsiding depth is analysed. The results may be employed for the design of constructions and underground facilities.

JTAM, Sofia, vol. 15 Issue 2 pp. 059-065 (1984)
Investigation of Stress Waves on Anizothropic Rock Massif Using Lazer Holograph Technique

A. Dokukin, V. Trumbatchev, O. Slavin

The paper has been presented at the 4th National Congress of Theoretical and Applied Mechanics, Varna 1981.

JTAM, Sofia, vol. 15 Issue 2 pp. 066-073 (1984)
On a Class of Spectral Problems with Eigen Values in the Boundary Conditions

K. Danov
Fac. Math. Mech., University of Sofia "Kl. Ohridski", A. Ivanov 6

A homogeneous boundary spectral problem, involving a linear system of partial differential equations, is considered. Dispersion relations, providing the eigen values, and solvability conditions of the inhomogeneous problem are obtained. This approach reveals the errors, made in A. I. Leontiev's paper, published in Dokladi AN SSSR, 1976, vol. 29, 820-823. It specifies the coefficients in the Kortewegde Vries equation as well.

JTAM, Sofia, vol. 15 Issue 2 pp. 074-077 (1984)
A Method for Reducing the Number of Arguments in Systems of Partial Differential Equations with Variable Coefficients

D. Kolarov
Inst. Mech. Biomech., Bulg. Acad. Sci., B1. 8 Cleo Milev

A rather general method for reducing the number of arguments in systems of linear partial differential equations with variable coefficients is presented. By means of this method a given system is transformed into an equivalent system of partial differential equations containing a smaller number of arguments as well as some parameters and undetermined integration functions or constants. So in many cases a system of ordinary differential equations may be reached to. The two argument case of linear partial differential equations system with variable coefficients is considered in detail. As an example the method is applied to systems of usual equations of the mathematical physics with variable coefficients. The method's presentation follows a certain algorithm until reaching a formal solution; this makes it convenient for using computer analytical transformation systems like REDUCE-2. The method is valid also to systems of linear partial differential equations with variable coefficients with more than two arguments as well as to some special kinds of nonlinearity. It is applicable to various problems in physics, continuum mechanics and other natural sciences.

JTAM, Sofia, vol. 15 Issue 2 pp. 078-085 (1984), [Full Article]

Free Oscillations of Continuous Rectangular Plates

Ho Za, T. Ganev
High. Inst. Arch. Civ. Eng., Hr. Smirnenski 1, Sofia

The method of finite strips (MFS) is applied to the determination of the frequencies of the free oscillations of continuous plates. Displacements along the strips are calculated by using functions, introduced by the authors. Their structure is simpler than that of the fundamental functions, involved in the MFS. The high accuracy thus obtained is illustrated by a number of applications.

JTAM, Sofia, vol. 15 Issue 2 pp. 086-091 (1984)
Stiffness Matrix of a Bar Supportedon Elastic Springs

V. Korošek

The paper has been presented at the 4th National Congress of Theoretical and Applied Mechanics, Varna 1981.

JTAM, Sofia, vol. 15 Issue 2 pp. 092-096 (1984), [Full Article]

Choice of Criteria for Work Capacity and Durability of Light Drills at High Temperatures

V. Gorbatenko, M. Danelyants
High. Inst. Arch. Civ. Eng., Hr. Smirnenski 1

The authors develop the idea that the high temperature desing of drills of aluminium alloys has to be based on the material long-term strength. The drill life may be estimated, regarding the minimum steady creep velocity.

JTAM, Sofia, vol. 15 Issue 2 pp. 097-103 (1984)