Issue 4

JTAM, Sofia, vol. 13 Issue 4 (1982)

Decoupling `Point-to-Point' Control of Industrial Robots

S. Patarinski1, M.M. Konstantinov2
1Inst. Mech. Biomech., Bulg. Acad. Sci.
2Inst. Techn. Cyb. Rob., Bulg. Acad. Sci,

The paper deals with problems of kinematic and dynamic decoupling of point-to-point motion of industrial robots. The results obtained make possible the synthesis of a stable closed loop system with prescribed dynamics. The approach presented may be generalized to the case of a continuous trajectory control. An illustrative example of a 3-degree of freedom plane manipulator is considered.

JTAM, Sofia, vol. 13 Issue 4 pp. 009-016 (1982)

A Numerical Method for the Kinematic Analysis of a CAM Mechanism

H. Varbanov1, L. Gel'man2
1Plovdiv, 5 Philip Makedonski Str.
2Textile Inst. "A. N. Kossigin", Moscow

A numerical method for the kinematic analysis of a cam mechanism with a roll link is investigated. The cam profile is specified in a tabular form. The method takes into consideration specificity of performing calculations on a digital computer. It provides for the obtaining of values of the function of link's position, angular velocity and angular acceleration.

JTAM, Sofia, vol. 13 Issue 4 pp. 017-022 (1982)

Calculation of the Electron Properties of Molecules and Large Clusters Using the Xα Method. II

G. Gadiak, V. Malkin, Y. Morokov

The paper presents a survey of different Xα methods. A comparison between them is made. Application to the solution of problems which involve the modelling of solid's surface and volume properties, is discussed.

JTAM, Sofia, vol. 13 Issue 4 pp. 023-033 (1982)

Prestressed Reinforced Concrete Thin-Walled Bars in an Elastic Medium

Sp. Pamukchiev
High. Inst. Arch. Civ. Eng., 1 Hr. Smirnenski Blvd., Sofia

The paper investigates the effect of the transversal bonds/beams, etc. on the stressed and strained state of prestressed reinforced concrete thin-walled beams. The transversal bonds are taken as an equivalent elastic medium. Since medium exercizes elastic forces on the bar, a deformational method is used for their calculation.

JTAM, Sofia, vol. 13 Issue 4 pp. 034-041 (1982)

On the Deformation of a Slowly Moving Fluid Drop in the Presence of a Deformable Interface

E. Chervenivanova
Inst. Mech. Biomech., Bulg. Acad. Sci., Bl. 8 Geo Milev

An analytic expression (in a first approximation) for the deformation of a slowly moving fluid drop is looked for, wherein a deformable inter-face is present. A quasisteady approach is adopted for that purpose. Pressure in the Stokes problem is determined as well, using the bispherical coordinate system introduced.

JTAM, Sofia, vol. 13 Issue 4 pp. 042-048 (1982)

Hydrodynamic Determination of the Horizontal Drainage Filtration of a Flux along a Sloping Confining Layer

A. Muleshkov
High. Inst. Arch. Civ. Eng., 1 Hr. Smirnenski Blvd., Sofia

Hydrodynamic solution of a flux laminar filtration upon a horizontal drainage is proposed. Flux comes from infinity and pours into a homogeneous area. It flows along a sloping confining layer. Depression curve, hydrodynamic network and relations between flux height and working region are constructed, wherein successive conform mappings are applied.

JTAM, Sofia, vol. 13 Issue 4 pp. 049-059 (1982)

A Plasticity Condition Considering Anisotropic, Thermal and Rate Effects

A. Baltov
Inst. Mech. Biomech., Bulg. Acad. Sci., Bl. 8 Geo Milev

A mechanical-mathematical model is proposed which covers quasi-dynamic processes where effects of preliminary and actual plastic deformation, strain rate and temperature are taken into account. A thermodynamic-structural approach is adopted and an experimental method for the determination of model's functions and parameters is proposed.

JTAM, Sofia, vol. 13 Issue 4 pp. 060-067 (1982)

An Algorithm Obtaining Complete Solutions of Two-Dimensional Problems in the Case of Perfect Plasticity

T. Balevski
Scientific – Technical Union "Technology of Metals", 43 Chapaev Str., Sofia

Two variational problems are formulated, considering stress and velocity functions. The functionals are transformed into quadratic forms and the direct Ritz method is used for minimization. Thus linear algebraic systems are obtained with respect to the variable coefficients in the function expansions. The algorithm proposed is applicable to two-dimensional and axisymmetric problems in the case of perfect plasticity.

JTAM, Sofia, vol. 13 Issue 4 pp. 068-072 (1982)

The Effect of the Deformation Factor on the Static and Cyclic Durability of Thermoplastic Polymers

I. Sgureva
High. Inst. Mech. Electr. Eng., Darvenitsa

The paper investigates effects of creep on the durability of polymer materials subjected to constant and variable loading. Experimental investigations involving different types of thermoplasts and loading conditions have been performed. A comparison between static and cyclic durability is made on the basis of equal deformations. It is found out that the type of loading does not affect considerably the durability characteristics. The difference between static and cyclic fracture durability is explained by the different relationship between strain and fracture rates. When a static loading is considered, fracture develops as a result of creep deformation nucleation. In the case of cyclic loading creep originates from the development of the fracture process.

JTAM, Sofia, vol. 13 Issue 4 pp. 073- (1982)