Issue 1
JTAM, Sofia, vol. 53 Issue 1 (2023)

ANALYSIS OF REFLECTION AND TRANSMISSION OF AXIALLY-SYMMETRIC WAVES FOR SELF-REINFORCED HALF SPACE OVER A POROELASTIC HALF SPACE

Rajitha Gurijala1, Sindhuja Ala2, Malla Reddy Perati2
1Sumathi Reddy Institute of Technology for Women, Hasanparthy, Warangal, Telangana, India
2Department of Mathematics, Kakatiya University, Warangal, Telangana, India


The objective of this paper is to study the reflection and transmission phenomena in axially symmetric waves in two half spaces, in which the lower one is poroelastic half space, and the upper one is self-reinforced half space. Employing Biot's theory of wave propagation, reflection and transmission coefficients of two dilatational waves, and shear wave are computed against angle of incidence. Numerical results are presented graphically for two types of poroelastic solids, namely, for upper half space, self-reinforced material with the longitudinal, shear modulus and reinforcement parameters respectively and for lower half space the sandstone saturated with water is used. From the numerical results, it is clear that the reflection and transmission coefficients are strongly affected as a function of angle of incidence.

JTAM, Sofia, vol. 53 Issue 1 pp. 003-018 (2023), [Full Article]

MINIMIZATION OF THE DRIVE TORQUE OF THE TROLLEY MOVEMENT MECHANISM DURING TOWER CRANE STEADY SLEWING

Viatcheslav Loveikin1, Yuriy Romasevych1, Andrii Loveikin2, Lyubov Shymko3, Anastasia Liashko1
1Department of Machines and Equipment Design, National University of Life and Environmental Sciences of Ukraine, Kyiv, 03041, Ukraine
2Mechanics and Mathematics Faculty, Taras Shevchenko National University of Kyiv, Kyiv, 01033, Ukraine
3Mechanical and Technological Department, National University of Life and Environmental Sciences of Ukraine, Kyiv, 03041, Ukraine

In the article, the optimization of the trolley movement along the boom during steady slewing of the tower crane which provides minimization of the driving force is considered. The optimization was performed using a mathematical model of the mechanism of the trolley movement, which is presented by the system of differential equations. This system is reduced to the one differential equation of the sixth order, which describes the moving torque of the mechanism of the trolley movement.

The variational problem of minimization of the root mean square value of the moving torque of the trolley movement mechanism is stated and solved. In the process of optimization, low- (pendulum) and high-frequency (caused by the change in moving torque of the mechanism) oscillations of the elements of the mechanism during its start are revealed. These oscillations are eliminated at the beginning of the steady movement due to the optimal start mode.

In the process of solving the variational problem, the minimum condition of the integral functional (root mean square value of the moving torque of the trolley movement mechanism), represented by a linear differential equation of the twelfth order, is solved by analytical methods. The obtained result — trolley optimal movement law — was analyzed based on kinematic, dynamic, and energy features. The smoothness of the movement, elimination of the low- and high-frequency oscillations, and minimizations of root mean square value of drive torque during start are the main advantages of the calculated optimal control.

JTAM, Sofia, vol. 53 Issue 1 pp. 019-033 (2023), [Full Article]

STUDY OF CURVATURE EFFECT ON STONELEY WAVE PROPAGATION IN DISSIPATIVE POROELASTIC CYLINDRICAL SOLIDS

Balu Chandavath1, Ramesh Modem2, Malla Reddy Perati1
1Department of Mathematics, Kakatiya University, Warangal, India
2Department of Mathematics, UCT, Osmania University, Hyderabad, India

Interface between two dissimilar solids is very common in natural structures and manmade structures. Wave propagation along the interface of poroelastic cylindrical solid with a different poroelastic medium is studied in the framework of Biot's isotropic poroelasticity. Both cylindrical solid, and surrounded medium are assumed to be dissipative. Two types of interfaces namely welded contact and smooth contact are considered. Axisymmetric waves are considered to make the problem two dimensional. Frequency equation of expected Stoneley waves is obtained for pervious interface. When the angular wavenumber is zero, the frequency equation is degenerated into two parts that are pertaining to dilatational and equivoluminal cases.

JTAM, Sofia, vol. 53 Issue 1 pp. 034-048 (2023), [Full Article]

MODELING OF CUTTING FORCE AND POWER CONSUMPTION USING ANN AND RSM METHODS IN TURNING OF AISI D3: COMPARATIVE STUDY AND PRECISION BENEFIT

Khaoula Safi1, Mohamed Athmane Yallese1, Salim Belhadi1, Tarek Mabrouki2, Salim Chihaoui1
1Université 8 Mai 1945, Guelma, Laboratoire (LMS), Algérie
2Université de Tunis El Manar, ENIT, Laboratoire (MAI), Tunisie

The present work deals with the optimization of cutting parameters when turning D3 steel using a CVD multi-layer coated carbide tool (Al2O3+TiC+TiCN). For that, response surface methodology (RSM) and artificial neural network (ANN) were adopted for the modeling of cutting force (Fz) and cutting power evolutions (Pc). The applied precited approaches were also compared and their results were discussed. Moreover, a design of experimental (DoF) based on Taguchi L16 (4^3 2^1) method was adopted. This has helped to illustrate the relationship between cutting parameters (tool radius, cutting speed, feed rate and cutting depth) and selected responses which are cutting force and cutting power. The results revealed that the ANN and RSM exhibited very good accuracy with experimental data. However, the ANN prediction model provides the maximum benefit in terms of precision compared to the RSM model. For (Fz and Pc) the benefit is (7.5 and 16.3)%, respectively.

JTAM, Sofia, vol. 53 Issue 1 pp. 049-065 (2023), [Full Article]

IMPACT OF VARIABLE PASSAGE SECTION AND ZIGZAG ABSORBER ON THE THERMAL PERFORMANCE OF A THERMO-SOLAR CONVERTER FOR DRYING

Fethi Moussa Boudjema1, Hamidou Benzenine1,2
1Smart Structures Laboratory, Faculty of Science and Technology, University Belhadj Bouchaib BP 284, Ain Témouchent, 46000, Algeria
2Laboratory of Energetic and Applied Thermal (ETAP), Faculty of Technology, B.P 230, University of Tlemcen, 13000, Algeria

This paper presents a numerical study of a two-dimensional laminar airflow transferred in a thermo-solar collector with forced convection. Simulations were processed to determine and analyze the dynamic and thermal fields under the influence of variation of collector configuration. Two cases of collector geometry (model of narrowing at exit and model of widening at entry) were studied and compared to the simple case uniform solar collector based on variations in temperature and velocity at the collector outlet for an input velocity varying between 0.04 and 0.11 m/s. The results show that the collector equipped with a zigzag-shaped absorber with a narrowing of the section at the outlet or widening at the inlet contribute to the thermal and dynamic improvement of the flow in the air stream compared with a simple case. The best performing case is recorded for the narrowest case of the exit shrinkage model where the exit velocity has been increased by 250%. this velocity reduces the drying time and increases the efficiency of the evacuation of the humid air leaving the chamber.

JTAM, Sofia, vol. 53 Issue 1 pp. 066-081 (2023), [Full Article]

IMPROVING THE ACCURACY OF SURFACE WEAR MEASUREMENTS OF MACHINES PARTS

Tareq M.A. Al-Quraan1, V. Kvasnikov2, M. Kataieva2
1Al-Balqa Applied University, Ma'an College, Technical Sciences Department, 19117 Al-Balqa, Jordan
2National Aviation University, 03058 Kyiv, Ukraine

The article considers the method of increasing the accuracy and speed of measurement of wear and deformation of parts by modern information-measuring complexes. The method helps to solve the problem of simultaneous provision of two contradictory requirements — high accuracy and sufficient speed of measurements. The authors propose a variant of the switched structure of the controller of the tracking system and perform mathematical modeling of its operation. The advantage of the proposed structure of the controller is to ensure high-quality operation in several modes: software movement of the measuring element at high speeds with minimal deviation from the specified trajectory, rigid positioning with step control without over-regulation, high sensitivity at small movements in the measurement area.The results of the study can be used in the development of precision automated drives for automated measuring systems of high accuracy and performance.

JTAM, Sofia, vol. 53 Issue 1 pp. 082-096 (2023), [Full Article]