Issue 1

JTAM, Sofia, vol. 3 Issue 1 (1972)

On the Spacial Waves in Trans-versally Isotropic (Monotropic) Elastic Media of Most General Type in Rectangular Co-ordinate System

Iv.Hr. Ganev
Hr. Smirnenski st. No 40, Sofia

Spacial waves propagating in isotropic elastic media of most general type in rectangular co-ordinate system are investigated. By means of linear functions of the spacial co-ordinates and time the general solution of the differential equations of the threedimensional dynamic problem is sought in displacements. The roots of the obtained characteristic equation are investigated. The total solutions for three displacements are obtained by means of six arbitrary functions. The effect of the mass forces is studied.

JTAM, Sofia, vol. 3 Issue 1 pp. 009-022 (1972)

Structural Programming of the Mechanisms

M.S. Konstantinov
Higher Institute of Mechanical Engineering “Lenin”, Darvenitza, Sofia

The structural classification of the plane mechanisms is studied and programm modelling of the relative transmission functions is performed.

JTAM, Sofia, vol. 3 Issue 1 pp. 023-032 (1972)

Determination of the Critical Forces of Jointly Supported Rods with Variable Cross Sections

L. Sa1chev, V. Popov, G. Mandichev
Higher Institute of Mechanical Engineering “Lenin”, Darvenitza, Sofia

A formula is found for the critical forces of jointly caught rods with cross sections which inertia moments vary according to degree law at arbitrary index. For determination of the pseudoperiod πy nomograms are given in (10). The utility of the introduced method can be seen from the comparisons given at the end of the paper for the results obtained from other authors.

JTAM, Sofia, vol. 3 Issue 1 pp. 033-042 (1972)

Investigation of Pre-stressed Reinforced Concrete Thin-walled Rods Subjected to Oscillation

S.Tz. Pamukchiev
Higher Institute of Civil Engineering, Hr. Smirnenski St., No 1, Sofia

The differential equations of free oscillations of pre-stressed reinforced concrete thin-walled rods are deduced. The Bubnov-Gal’orkin’s method is used for the solution of the oscillation equation. It is proved that the constructor can affect considerably the frequencies of oscillation of the thin-walled rod choosing expediently the magnitude and the position of the stressing force. Some cases for determination of the frequencies of oscillation are considered and interesting conclusions are drawn.

JTAM, Sofia, vol. 3 Issue 1 pp. 043-052 (1972)

Stability of the Periodic Oscillations of Quasilinear Autonomous Delay Systems

V.L. Lubih, D.D. Bajnov
Higher Institute of Electrical Engineering “Lenin”, Darvenitza, Sofia

Quasilinear autonomous delay system is considered. Sufficient conditions for asymptotic stability of some periodic solutions of the considered system are found.

JTAM, Sofia, vol. 3 Issue 1 pp. 053-060 (1972)

Axisymmetric Problem for the Loss of Stability of a Pre-stressed Cylinder

Z. Vesolovski, E. Zlatanova, J. Momchinski

The stability of a pre-stressed elastic cylinder, obtained after cutting and adding of a wedge with arbitrary apex angle, and subjected to tension or pressure is studied. The equations of the axisymmetric problem for incompressible material with arbitrary characteristics are deduced. The theory of the small additional displacements, imposed on finite deformations is used. A numerical solution is found for concrete material and graphs of the apex critical angle of the wedge are drawn, representing the critical elongation.

JTAM, Sofia, vol. 3 Issue 1 pp. 061-070 (1972)

Prismatic Console, Operating on Shear, under the Action of Momentary Pulse

L. Tzenov
Institute of Technical Mechanics, Bulgarian Academy of Sciences, “Geo Milev” district, Sofia

Elastic, elasto-plastic and rigid-plastic consoles, subjected to momentary pulse are considered, the deformations of shear only being taken into account. The formulae determining the maximum translations are deduced. At given momentary pulse and accepted admissible maximum translation these formulae can also be used for dimensioning.

JTAM, Sofia, vol. 3 Issue 1 pp. 071-080 (1972)

Determination of the Basic Dynamic Characteristics of the Lowest Reverse Symmetric Form of Eigenoscillations of Arch Dam

An.A. Losaberidze1, St. Grigorov2
1Georgian Academy of Sciences
2Institute of Technical Mechanics, Bulgarian Academy of Sciences, “Geo Milev” district, Sofia

A discrete model for calculation is used. Only two symmetrically located consoles are taken into account and the effect of the rest on the arch is substituted with distributed load. The sought dynamic characteristics of the arch dam can be determined by means of the approximate energetic method of the dynamics.

JTAM, Sofia, vol. 3 Issue 1 pp. 081-090 (1972)