Applied sciences

Archive of Mechanical Engineering

Content

Archive of Mechanical Engineering | 2017 | vol. 64 | No 4 |

Abstract

In this article, the fracture behavior of functionally graded thick-walled cylinder under thermo-mechanical shock is investigated. For this purpose, classical coupled thermoelastic equations are used in calculations. First, these equations are discretized with extended finite element method (XFEM) in the space domain and then they are solved by the Newmark method in the time domain. The most general form of interaction integral is extracted for axially symmetric circumferential crack in a cylinder under thermal and mechanical loads in functionally graded materials and is used to calculate dynamic stress intensity factors (SIFs). The problem solution has been implemented in MATLAB software.

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Abstract

Inclined jet air cooling can be effectively used for cooling of electronics or other such applications. The non-confined air jet is impinged and experimentally investigated on the hot target surface to be cooled, which is placed horizontally. Analysis and evaluations are made by introduction of a jet on the leading edge and investigated for downhill side cooling to identify cold spots. The jet Reynolds number in the range of 2000 ≤ Re ≤ 20000 is examined with a circular jet for inclination (Ɵ) of 15 < Ɵ < 75 degree. Also, the consequence of a jet to target distance (H) is explored in the range 0.5 ≤ H/D ≤ 6.8. For 45 degree jet impingement, the maximum Nusselt number is widely spread. Location of maximum Nusselt number is studied, which indicates cold spots identification. At a higher angle ratio, the angle is the dominating parameter compared to the Reynolds Number. Whereas at a lower angle ratio, the inclined jet with a higher Reynolds number is giving the cooling point away from leading edge. It is observed that for a particular angle of incident location of maximum Nusselt Number, measured from leading edge of target, is ahead than that of stagnation point in stated conditions.

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Abstract

Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. %=0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.

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Abstract

Analytical and numerical nonlinear solutions for rotating variable-thickness functionally graded solid and annular disks with viscoelastic orthotropic material properties are presented by using the method of successive approximations. Variable material properties such as Young’s moduli, density and thickness of the disk, are first introduced to obtain the governing equation. As a second step, the method of successive approximations is proposed to get the nonlinear solution of the problem. In the third step, the method of effective moduli is deduced to reduce the problem to the corresponding one of a homogeneous but anisotropic material. The results of viscoelastic stresses and radial displacement are obtained for annular and solid disks of different profiles and graphically illustrated. The calculated results are compared and the effects due to many parameters are discussed.

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Abstract

In this paper, pole placement-based design and analysis of a free piston Stirling engine (FPSE) is presented and compared to the well-defined Beale number design technique. First, dynamic and thermodynamic equations governing the engine system are extracted. Then, linear dynamics of the free piston Stirling engine are studied using dynamic systems theory tools such as root locus. Accordingly, the effects of variations of design parameters such as mass of pistons, stiffness of springs, and frictional damping on the locations of dominant closed-loop poles are investigated. The design procedure is thus conducted to place the dominant poles of the dynamic system at desired locations on the s-plane so that the unstable dynamics, which is the required criterion for energy generation, is achieved. Next, the closed-loop poles are selected based on a desired frequency so that a periodical system is found. Consequently, the design parameters, including mass and spring stiffness for both power and displacer pistons, are obtained. Finally, the engine power is calculated through the proposed control-based analysis and the result is compared to those of the experimental work and the Beale number approach. The outcomes of this work clearly reveal the effectiveness of the control-based design technique of FPSEs compared to the well-known approaches such as Beale number.

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Abstract

In the paper, the authors discuss the numerical and experimental modal analysis of the cantilever thin-walled beams made of a carbon-epoxy laminate. Two types of beams were considered: circumferentially asymmetric stiffness (i.e., CAS) and circumferentially uniform stiffness (i.e., CUS) beams. The layer-up configurations of the laminate were chosen to get a vibration mode coupling effect in both analysed cases. The aim of the paper was to perform the numerical and experimental modal analysis of the composite structures, when a flapwise bending with torsion coupling effect or flapwise-chordwise bending coupling effect took place. Firstly, numerical studies by the finite element method was performed. The numerical simulations were carried out by the Lanczos method in the Abaqus software package. The natural frequencies and the corresponding free vibration modes were determined. Next, the experimental modal analyses of the CAS and CUS beams were performed. The test stand was consisted of a special grip, two beams with an adhered holder, the LMS Scadas III system with a modal hammer and an acceleration sensor. Finally, the results of both methods were compared.

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Abstract

In the present article, we introduced a new model of the equations of general ized thermoelasticity for unbounded orthotropic body containing a cylindrical cavity. We applied this model in the context of generalized thermoelasticity with phase-lags under the effect of rotation. In this case, the thermal conductivity of the material is considered to be variable. In addition, the cylinder surface is traction free and subjected to a uniform unit step temperature. Using the Laplace transform technique, the distributions of the temperature, displacement, radial stress and hoop stress are determined. A detailed analysis of the effects of rotation, phase-lags and the variability thermal conductivity parameters on the studied fields is discussed. Numerical results for the studied fields are illustrated graphically in the presence and absence of rotation.

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Editorial office

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

  

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Instructions for authors

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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