# 3(32), 2008
DESIGNING OF SPHERICAL FIVE-BAR LINKAGE MECHANISMS WITH VARYABLE DIMENSIONS OF LINKS. N. Davitashvili, O. Gelashvili. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 5-15, (Engl.).
In work is given the research and designing of the spherical five-bar linkage mechanisms with the variable dimensions of links. It is shown, that such mechanism represents to each moment of motion the spherical four-bar mechanism and at transition from one position in another in the mechanism are changing the lengths of some links. Designing of the specified spherical five-bar mechanism is lead with preliminary set of the swinging angle and durations of time of swings (stops) of the output link. 6 ill. Bibl. 14. Engl.; summ. in Russ.
Analysis of a flexible worm locomotion based on a reduced method. Kolev Emil Kolev, Victor Alexeevich Chirikov, Klaus Zimmermann. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 16-22, (Engl.).
Nowadays, concerning the contemporary purposes of development in Techniques and Medicine, non-pedal systems motion are more often considered.
In the presented paper a reduced dynamical model for the locomotion of a flexible worm structure in a straight channel is introduced. Reduced model applied in the paper to a continuous system means neglecting of its less important degrees of freedom. Explicitly defined structure nodes appears to be the system coordinates. The worm body position is approximated by a polynomial function passing through the nodes, so analytical formulation of the worm shape is significantly reduced. This way the dynamical problem leads to a number of node coordinates change that are assumed as generalized coordinates of the moving system. The fundamental property of the introduced system's polynomial is the zero slopes at the contact points. During the motion all other points are lying on a smooth curve, forming the elastic function of the worm structure. The essential difference from the FEM model is that the nodes of the reduced model do not represent the element bounds and must be assumed as characteristic points of the dynamical system position.
The motion starts from the initial position, where the beam is elastically deformed in the sine shape contacting simultaneously at four points the channel walls.
For the considered analytical problem we use the Lagrange’s equations, as they can be easily programmed in the environment of the well-known MAPLE package for computer algebra. For the better presentation only two degrees of freedom dynamic model is presented.
Movement of the considered object is calculated in different stages. At each stage some contact points abandon the channel surface, while the others keep on contact, or establish new contact and later on vice versa.
The obtained solutions for the different phases are presented in figures.
The presented method allows computing a continuous mechanical object in a simpler way than FEM. Besides, the task of model parameters optimization resolves easier, the problems concerning the object control and drive including. 10 ill. Bibl. 6. Engl.; summ. in Russ.
Structure and kinematics of reflector’s transformed mechanical systems. E. Medzmariashvili, V. Gogilashvili, Sh. Tserodze, N. Tsignadze, N. Siradze. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 23-33, (Engl.).
In work are considered the asymmetrical closed system, consisting from the lever elements which transformation carried out on the fictitious tapered surface, that is caused by a irregular arrangement of levers peripheral hinges concerning the central hinges. Is determined the law of motion and geometrical parameters of system, that provides the synthesis task solution with taking into consideration the initial parameters. Also is presented the basic scheme and the structural analysis of the chain system transformed on the spherical surface. 12 ill. Bibl. 4. Engl.; summ. in Russ.
Innovations in movable magnetic field solution of faraday’s problem. H. Tsulaia. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 34-39, (Engl.).
A new property of the magnet has been discovered, which lies in the fact that during its cyclical motion in certain conditions it retains immovable magnetic field within the magnetic field moving together with it. During rotation of the magnet a correlation between moving and immovable magnetic fields depends on the size of permanent overlapping zone of the magnetic field moving in space and time. Movable and immovable magnetic fields act independently. 7 ill. Engl.; summ. in Russ.
Approximate method of high-altitude large-panel buildings analysis at longitudinal dynamic action of loading in view of elastic properties of building and footing material. S. Daveyan. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 40-46, (Engl.).
In article are presented the approximate calculation of a high-altitude large-panel building at longitudinal dynamic influence of loading in view of elastic properties of the building and footing material. At calculation compressibility of the building material is subtracted. As a result of the analysis of the theory of calculation it has been established, that for low buildings the account of elasticity of the wall material is not reflected in its fluctuations, therefore walls of a building can be accepted as absolutely rigid. With increase in height of a building the account of elasticity becomes necessary 1 ill. Bibl. 2. Engl.; summ. in Russ.
THERMODYNAMIC RESEARCH OF JOINT OPERATION OF THE DIESEL ENGINE AND FREE TURBO-COMPRESSOR UNDER HIGH ALTITUDE CONDITIONS. B. Kordzadze, T. Natriashvili. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 47-51, (Engl.).
On the basis of revealed conformity with a law of thermo dynamics in the course of the experimental researches of joint operation of the diesel engine and free turbo-compressor under high altitude conditions, a mathematical model of variation of the turbo-supercharged diesel power in the form of simple operation is offered, which not only describes experimental data but also explains them. In drawing it up, admissions having experimental proofs are used. 4 ill. Bibl. 2. Engl.; summ. in Russ.
THEORETICAL INVESTIGATION OF GRINDING THE TEA ROOT SYSTEM IN THE SOIL. R. Makharoblidze, Z. Makharoblidze , B. Goshadze. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 52-56, (Engl.).
The paper deals with the theoretical study of grinding the tea root system in the soil. By using the theory of impact, the cutting process of the vegetable materials in the elastic-plastic environment has been studied and methods for engineering calculation of power and energy characteristics of the cutting-and-grinding process of the vegetation materials in the soil have been developed. The results gained through the study have been realized by a practical example. 1 ill. Bibl. 3. Engl.; summ. in Russ.
ON ONE REASON OF DISTURBANCE OF ECOLOGICAL PURITY OF THE AUTOMOBILE. A. Muchaidze, T. Natriashvili, Kh. Mgebrishvili, N. Topuria. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 57-60, (Engl.).
The process of dispersal of the automobile is analysed. The occurrence in structure of the fulfilled gases of products of incompleteness of combustion on this mode - phenomenon natural, caused by infringement of the moment of ignition of a working mix and temperature mode of details of the engine is shown, that. Because of it combustion of a working mix is partially transferred on process of expansion, as is the inevitable reason of infringement of ecological cleanliness of the automobile. Bibl. 4. Engl.; summ. in Russ.
HEAT EXCHANGE AT LAMINAR MOTION OF INCOMPRESSIBLE LIQUID WITH VARIABLE PHYSICAL PROPERTIES IN THE PIPE WITH POROUS WALLS. V. Tsutskiridze. “Problems of Mechanics”. Tbilisi. 2008, N 3(32), pp. 61-64, (Engl.).
Using the method of local similarity, the numerical solutions of the equations of motion and energy in the circular pipe with blowing-in are obtained. Bibl. 10. Engl.; summ. in Russ.
CHECKING CRITERIA OF MATHEMATICAL MODELS FOR PRODUCT AND
POWER OF ONE VARIABLE FUNCTIONS OF ARGUMENTS OF MULTIVARIABLE FUNCTION. I. Gorjoladze,
N. Gorjoladze. “Problems of Mechanics”. Tbilisi. 2008,
N 3(32), pp. 65-68, (Engl.).
The checking criteria of mathematical models for product and power of one variable functions of arguments of a multivariable function, which ensure the existence of analytical form corresponded to the model, is received. Bibl. 4. Engl.; summ. in Russ.
THE BOUNDARY VALUE PROBLEMS OF
INCOMPRESSIBLE VISCIOUS FLUID STATIONARY CURRENT FOR STRETCHED SPHEROID. K.
M. Khmiadashvili, M. Kharashvili. “Problems of Mechanics”. Tbilisi. 2008, N 3(32),
pp. 69-79, (Engl.).
The boundary value problem of incompressible viscous fluid stationary current for stretched spheroid are solved in case the limit values of velocity, or potential vectors are assigned. The solution of considered problems are searched in form analogue of Papcovich-Neiber presentation. The solutions are obtained in the form of absolutely and uniformly convergent series. Bibl. 11. Engl.; summ. in Russ.