Nauki Techniczne

Archive of Mechanical Engineering

Zawartość

Archive of Mechanical Engineering | 2019 | vol. 66 | No 3 |

Abstrakt

LED light must be cooled to avoid reaching a certain temperature. Two different 3D practical domains of LED light are modelled, (i) square aluminium plate with a cylindrical plate and an LED module (model I), (ii) the same provision of model I with 25 fins (model II). ANSYS 16.0 is used for solving the problem. Temperature distribution, junction temperature (Tj) and heat flux are estimated. Analyses are carried out for various ambient temperatures (Ta) and for different LED power dissipations (Q) to identify the safe operating conditions. In model I, it is found that 38% of working conditions go beyond the critical limit of Tj and it is reduced to 21.4% in model II. In model II, for low Ta of 30 and 40ºC with all Q considered in this analysis are safer. If Ta is between 30 and 80ºC, then Q must be maintained at 0.5 to 1.25 W. Beyond this, conditions are not safe.

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Abstrakt

This paper presents an extended finite element method applied to solve phase change problems taking into account natural convection in the liquid phase. It is assumed that the transition from one state to another, e.g., during the solidification of pure metals, is discontinuous and that the physical properties of the phases vary across the interface. According to the classical Stefan condition, the location, topology and rate of the interface changes are determined by the jump in the heat flux. The incompressible Navier-Stokes equations with the Boussinesq approximation of the natural convection flow are solved for the liquid phase. The no-slip condition for velocity and the melting/freezing condition for temperature are imposed on the interface using penalty method. The fractional four-step method is employed for analysing conjugate heat transfer and unsteady viscous flow. The phase interface is tracked by the level set method defined on the same finite element mesh. A new combination of extended basis functions is proposed to approximate the discontinuity in the derivative of the temperature, velocity and the pressure fields. The single-mesh approach is demonstrated using three two-dimensional benchmark problems. The results are compared with the numerical and experimental data obtained by other authors.

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Abstrakt

This work is devoted to the plotting of coupler curves in the environment of graphical programs. As there is a large variety of shapes, for the purpose of this study, the authors selected those curves that feature a cusp form. In the research, two software programs were used, i.e., AutoCAD and Rhinoceros with the Grasshopper plug-in. Two types of curves were defined: a fixed and a moving centrode, in which the points of the moving centrode define the coupler curves whose cusps are located on the fixed centrode. In conclusion, two design tools were compared and the curves in question were discussed in detail.

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Abstrakt

In the present work, an experimental investigation of a transverse fatigue crack has been carried out. A mathematical modelling of cracked rotor system along with the measured vibration is used to find crack parameters that not only detect the fault but also quantify it. Many experimental studies on cracks considered the crack as a slit or notch, which remains open. However, such flaws do not mimic a fatigue crack behavior, in which crack front opens and closes (i.e., breathes in a single revolution of the rotor). The fatigue crack in rotors commonly depicts 2x frequency component in the response, as well as higher frequency components, such as 3x, 4x and so on. In rotors, both forward and backward whirling take place due to asymmetry in rotor, and thus the fatigue crack gives the forward and backward whirl for all such harmonics. A rotor test rig was developed with a fatigue crack in it; rotor motions in two orthogonal directions were captured from the rig at discrete rotor angular speeds using proximity probes. The directional-spectrum processing technique has been utilized to the measured displacements to get its forward and backward whirl components. Subsequently, it is executed in a mathematical model-based estimation procedure to obtain the crack forces, residual unbalances, and remaining rotor system unknown variables. Estimation of crack forces during rotation of the shaft gives its characteristics, which can be used further to develop newer crack models.

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Abstrakt

In times of rapidly progressing globalization, the possibility of fast long-distance travel between high traffic cities has become an extremely important issue. Currently, available transportation systems have numerous limitations, therefore, the idea of a high-speed transportation system moving in reduced-pressure conditions has emerged recently. This paper presents an approach to the modelling and simulation of the dynamic behaviour of a simplified high-speed vehicle that hovers over the track as a magnetically levitated system. The developed model is used for control system design. The purpose of passive and active suspension discussed in the text is to improve both the performance and stability of the vehicle as well as ride comfort of passengers travelling in a compartment. Comparative numerical studies are performed and the results of the simulations are reported in the paper with the intent to demonstrate the benefits of the approach employed here.

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Abstrakt

The paper describes the dynamics of a composite cantilever beam with an active element. The vibrations of the kinematically excited beam are controlled with the use of a Macro Fiber Composite actuator. A proportional control algorithm is considered. During the analysis, actuator is powered by a time-varying voltage signal that is changed proportionally to the beam deflection. The MFC element control system with the implemented algorithm allowed for changing the stiffness of the tested structure. This is confirmed by the numerical and experimental results. Resonance curves for the beam with and without control are determined. The results show a very good agreement in qualitative terms.

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Redakcja

Editor-in-Chief

Prof. Marek Wojtyra, Warsaw University of Technology, Poland

 

Editorial Board

Prof. Krzysztof Arczewski, Warsaw University of Technology, Poland

Prof. Janusz T. Cieśliński, Gdańsk University of Technology, Poland

Prof. Antonio Delgado, LSTM University of Erlangen-Nuremberg, Germany

Prof. Peter Eberhard, University of Stuttgart, Germany

Prof. Jerzy Maciej Floryan, The University of Western Ontario, Canada

Prof. Janusz Frączek, Warsaw University of Technology, Poland

Prof. Tadeusz Ryszard Fodemski, Technical University of Lodz, Poland

Prof. Zbigniew Kowalewski, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland

Prof. Zenon Mróz, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland

Prof. Andrzej J. Nowak, Silesian University of Technology, Poland

Dr. Andrzej F. Nowakowski, The University of Sheffield, United Kingdom

Prof. Jerzy Sąsiadek, Carleton University, Canada

Prof. Jacek Szumbarski, Warsaw University of Technology, Poland

Prof. Tomasz Wiśniewski, Warsaw University of Technology, Poland

Prof. Günter Wozniak, Chemnitz University of Technology, Germany

 

Assistant to the Editor

Małgorzata Broszkiewicz, Warsaw University of Technology, Poland

 

Editorial Advisory Board

Prof. Alberto Carpinteri, Politecnico di Torino, Italy

Prof. Fernand Ellyin, University of Alberta, Canada

Prof. Feng Gao, Shanghai Jiao Tong University, P.R. China

Prof. Emmanuel E. Gdoutos, Democritus University of Thrace, Greece

Prof. Gregory Glinka, University of Waterloo, Ontario, Canada

Prof. Andrius Marcinkevicius, Vilnius Gedeminas Technical University, Lithuania

Prof. Manuel José Moreira De Freitas, Instituto Superior Tecnico, Portugal

Prof. Andrzej Neimitz, Kielce University of Technology, Poland

Prof. Thierry Palin-Luc, Arts et Métiers ParisTech, Institut Carnot Arts, France

Prof. Andre Pineau, Centre des Matériaux, Ecole des Mines de Paris, France

Prof. Narayanaswami Ranganathan, LMR, Ecole Polytechnique de l'Université de Tours, France

Prof. Jan Ryś, Cracow University of Technology, Poland

Prof. Adelia Sequeira, Technical University of Lisbon, Portugal,

Prof. Józef Szala, University of Technology and Life Sciences in Bydgoszcz, Poland

Prof. Edmund Wittbrodt, Gdańsk University of Technology, Poland

Prof. Jens Wittenburg, Karlsruhe Institute of Technology, Germany

Prof. Stanisław Wojciech, University of Bielsko-Biała, Poland

 

Language Editor

Lech Śliwa, Institute of Physiology and Pathology of Hearing, Warsaw, Poland

  

Kontakt

ARCHIVE OF MECHANICAL ENGINEERING

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Instrukcje dla autorów

About the Journal
Archive of Mechanical Engineering is an international journal publishing works of wide significance, originality and relevance in most branches of mechanical engineering. The journal is peer-reviewed and is published both in electronic and printed form. Archive of Mechanical Engineering publishes original papers which have not been previously published in other journal, and are not being prepared for publication elsewhere. The publisher will not be held legally responsible should there be any claims for compensation. The journal accepts papers in English.

Archive of Mechanical Engineering is an Open Access journal. The journal does not have article processing charges (APCs) nor article submission charges.

Original high quality papers on the following topics are preferred:

  • Mechanics of Solids and Structures,
  • Fluid Dynamics,
  • Thermodynamics, Heat Transfer and Combustion,
  • Machine Design,
  • Computational Methods in Mechanical Engineering,
  • Robotics, Automation and Control,
  • Mechatronics and Micro-mechanical Systems,
  • Aeronautics and Aerospace Engineering,
  • Heat and Power Engineering.

All submissions to the AME should be made electronically via Editorial System - an online submission and peer review system at: https://www.editorialsystem.com/ame

More detailed instructions for Authors can be found there.

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