#4(49), 2012

SUMMARIES

kinematics research of seven-bar Automatic manipulator by analytical method. N. Davitashvili. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 5-10, (Engl.).

In stated the description of principle of operation and kinematical research by analytical method of seven-bar spherical automatic manipulator that is created on the basis of spherical four-bar slider-crank mechanism. The kinematical parameters - positions, linear and angular velocities and accelerations of links and their points of automatic manipulator are defined in the function of generalized coordinates and time. Results of research are available for synthesis of mentioned mechanism. The preconditions for dynamical analysis of manipulator are revealed. 2 ill. Bibl. 11. Engl.; sum. in Russian.

 

A contribution to the description of the mechanical behaviour of veneer using a linear-elastic orthotropic material model. Bernd Bellair, Andreas Dietzel, Martin Zimmermann, Hendrike Raßbach, Klaus Zimmermann. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 11-21, (Engl.).

The product development process as well as the production of laminated veneer lumber used for chairs and design objects is traditionally based on the experience of the staff. Such an experience based approach for developing forming tools and manufacturing sample parts requires an iterative process. Sample parts are checked for cracks and other optical defects (in-plane contraction) and changes to the 3D-design are made in collaboration with the designers. These iterations are essential until a high quality product is the result. In order to save time and money in the product development process, the feasibility of an initial 3D-design should be checked by means of simulation.

This article presents a methodology for the identification of material parameters on red beech veneer and the use of these characteristics in material models and failure criteria. The objective is to create the basis for the description of the mechanical behaviour of veneer under different climatic conditions, in order to simulate the 3D-forming process of laminated veneer lumber. Initially, the specific properties of veneer and the continuum mechanical principles are presented. Based on this, an appropriate experimental methodology and data processing is introduced. The results of the experiments are discussed and compared with simulation results. 9 ill. Bibl. 21. Engl.; sum. in Russian.

 

Constructive logic of created by double pantograph deployable load-bearing ring reflector. E. Medzmariashvili. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 22-36, (Engl.).

In the article, proceeding form construction principles and the theory of transformable systems is studied and developed the generalized model of reflector with deployable. It has the center composed of two mutually opposite concaved mesh. 33 ill. Bibl. 3. Engl.; sum. in Russian.

 

dynamical research of cone crusher drive mechanism by computing machinery. A. Talakvadze. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 37-47, (Engl.).

Is stated the dynamical research of cone crusher drive mechanism by computing machinery. As crusher drive is presented spherical crank-slider mechanism with clearances in two kinematical pairs, dynamical analysis of that is realized by taking into account the additional and basic motions of mechanism. Due the comparative analysis of obtained results is revealed the possibility of selection of optimal clearances in kinematical pairs, stipulating the normal and reliably operation of crusher drive. 8 ill. Bibl. 8. Engl.; sum. in Russian.

 

new method of transformation heat in compressor of cascade exchange by pressure. Aleksander Krajniuk, Oleh Klyus. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 48-52, (Engl.).

A new method of organization of working cycle of device of direct transformation of heat in the located work of compression of air, based on principle of cascade exchange by pressure, is exposed; the results of pre-selection of basic dimensional and structural parameters of thermal compressor of cascade exchange by pressure are adduced; some special features of its working process are considered; main directions of perfection of working cycle of thermal compressors of cascade exchange of pressure are shown. 4 ill. Bibl. 3. Engl.; sum. in Russian.

 

Transformation of heat into useful work in rotary fluid converter, as consequence of energy equation conflict with angular momentum conservation law. A. Aptsiauri. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 53-58, (Engl.).

In the article is stated with taking into account in the field of alternative energetics, is given a positive answer on the issue of useful work generation from environmental heat. Is shown that such a possibility, in particular, appears in such rotary installations in which is observed the evident conflict between the fundamental laws. The scheme of such installation is presented. 1 ill. Bibl. 10. Engl.; sum. in Russian.

 

calculation of City routes fuel consumption according to bus traffic conditions. O. Gelashvili, P. Bezhanishvili. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 59-62, (Engl.).

Are considered on city bus routes traffic conditions and fuel consumption calculation method according to the phases. At bus operation in urban conditions is proposed a new approach for determining the fuel consumption, that takes into account the engine structures and modes of operation. The original method has been developed that would be a basis for determining the fuel route consumption norms for bus operation in urban conditions. 2 ill. Bibl. 6. Engl.; sum. in Russian.

 

CONICAL REFLECTOR DEPLOYABLE RING STRUCTURE WITH V-FOLD BARS. Sh. Tserodze, E. Medzmariashvili, N. Tsignadze, O. Tusishvili, J. Santiago-Prowald. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 63-70, (Engl.).

In the article is considered the structural analysis of reflector thats unfolding ring is conical and central part is the net mesh. The ring supports are connected with V-fold bars. Here are given the structure of central joints connecting V-fold bars and the structure of joints connecting V-fold bars with posts. On all posts the V-fold bars deployment synchronization are arranged in joints of rods deployment synchronization, what with its determination is the novelty. The mentioned joint has ability of rotation towards its axis, which is the main condition for the deployment of conical ring. Stabilization and control of system deployment is carried out through the cables and driving devices. On flexible center the front and rear net meshes are connected with beams in parallel arrangement. 10 ill. Bibl. 3. Engl.; sum. in Russian.

 

THEORETICAL AND EXPERIMENTAL STUDY OF REFLECTOR ANTENNA. G. Bedukadze, E. Medzmariashvili, K. Chkhikvadze, M. Sanikidze. Problems of Mechanics. Tbilisi, 2012, 4(49 ), pp. 71-83, (Engl.).

Paper discusses the results of theoretical calculations of reflector with 4 meter aperture and its experimental researches. Experimental researches including the static and dynamic influences on reflector, study of its stability and determination of eigen frequencies. The results of surface accuracy and the shape repetition during the multiple deployments are given in experiment. 15 ill. Bibl. 8. Engl.; sum. in Russian.

 

Dynamics of machine-tractor unit with variable mass. R. Makharoblidze, I. Lagvilava, O. Asatiani, Yu. Dzirkvadze, A. Kobakhidze. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 84-88, (Engl.).

Is studied the dynamics of transition processes in the machine-tractor units with  variable mass at real change disconnect or joining masses that is most often used in the function of movement . Are derived the formulas of change of velocity of movement on displacement of unit and is defined the dependence of this velocity on the tractor and technological machine performance, with taking into account the gradual increase or removing of agricultural materials masses. Bibl. 3. Engl.; sum. in Russian.

 

on analysis of dynamics of aerial ropeway drive system. T. Mchedlishvili, D. Balakhadze, K. Demetrashvili, G. Nadirashvili, I. Elerdashvili. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 89-92, (Engl.).

To drive systems of aerial ropeways cars are raised increased requirements due points of technical performances view that in turn is largely depended on the effectiveness of used at their calculations mathematical models of dynamics. Due the latter would be determined kinematic and structural parameters of systems. In this article are considered the issues of mathematical models construction by that is possible the further improvement in the efficiency of computational researches. Bibl. 6. Engl.; sum. in Russian.

 

Effect of heat treatment on structure of low-silicon aluminum cast irons. N. Khidasheli, G. Beradze, G. Khvichia. Problems of Mechanics. Tbilisi, 2012, 4 (49), pp. 93-97, (Engl.).

In the present work are researched the processes of austenitizing and austenite dissociation in low-silicon aluminum cast irons. Are defined the time-temperature parameters of bainite and martensite structures in the mentioned alloys. The active effect of aluminum on phase composition of cast iron after the heat treatment is shown. 6 ill. Bibl. 11. Engl.; sum. in Russian.

 

STRAIN CONTINUITY EQUATIONS IN CASE OF A PLANE PROBLEM IN STRESSES. N. Berishvili, N. Tsignadze, N. Medzmariashvili. Problems of Mechanics. Tbilisi, 2012, 4(49), pp. 98-100, (Engl.).

In the theory of elasticity, only a single equation that expresses relation between longitudinal relative strains and angular strains remains from the system of strain continuity equations in case of a plane problem, i.e. where the influence of the third coordinate can be neglected. In the classical elasticity theory, Hookes generalized law is used for expressing the continuity equations by stresses. Therefore, the stresses appearing in the continuity equations are partial stresses, upon which influence of normally directed loads are not reflected. In the present work, strains are expressed by so called full stresses, envisioning influence of the above mentioned loads. While the thus obtained Morris Levi condition is similar as to form, the stresses included therein have different physical essence whatsoever. Bibl. 4. Engl.; sum. in Russian.

 

PROPERTY OF AND FUNCTIONS AT CONSTANT VOLUME FORCES. N. Berishvili, N. Tsignadze, N. Medzmariashvili. Problems of Mechanics. Tbilisi, 2012, 4(49 ), pp. 101-103, (Engl.).

It is known from the classical theory of elasticity that functions expressing the first invariant of volume strain and stress state are harmonic functions. Differential equations of equilibrium expressed by means of displacements wherein the associations between the stresses and strains depend upon Lames elastic constants were used for proving this tenet. In the present work, a new sort of differential equations of equilibrium is used that involves associations between real stresses and strains, and the first invariant of the stresses state is considered to be the sum of full normal stress. In spite of this difference it is shown that and functions as well are harmonic functions. Bibl. 3. Engl.; sum. in Russian.