فهرست مطالب

Mechanical Engineering Transactions of ISME - Volume:21 Issue: 1, Mar 2020

Iranian Journal of Mechanical Engineering Transactions of ISME
Volume:21 Issue: 1, Mar 2020

  • تاریخ انتشار: 1399/05/22
  • تعداد عناوین: 7
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  • Farzan Rashidi *, Halimeh Rashidi Pages 5-20
    Utilizing the combined cooling, heating and power generation (CHP) systems to produce cooling, heat and electricity is growing rapidly due to their high efficiency and low emissions in commercial and industrial applications. In conventional CHP systems the deficit of the system power can be purchased from the grid. However, this system cannot be used as the standalone application. The hybrid solar micro-CHP system can be worked as a standalone system for remote areas and other places which the access to grid is hard and costly. In this paper, by using energy and economic analyses, the type and the number of the required microturbines for the specific electricity and heat load curves during a year are selected. For performing this task, maximizing the actual annual benefit of the system is considered as objective function. Then, particle swarm optimization (PSO) algorithm and local unimodal sampling (LUS) technique is developed to calculate the type and number of prime mover and also the area of photovoltaic panels.
    Keywords: Microturbine, ‎photovoltaic ‎panels, CHP, PSO ‎algorithm, LUS technique
  • Javad Ehyaei *, Hamed Safarpour, Esmaeil Shahabinejad Pages 21-44
    In this paper, dynamic modeling of a double layer cylindrical functionally graded (FG) microshell is considered. Modeling is based on the first-order shear deformation theory (FSDT), and the equations of motion are derived using the Hamilton's principle. It assumes that functionally graded length scale parameter changes along the thickness. Generalized differential quadrature method (GDQM) is used to discretize the model and solve the problem.  In this research the size effect is investigated using a new modified couple stress theory (MCST) which has been considered for the first time in the present study. The accuracy of the presented model is validated with some cases in the literature. Considering the microshell as double layer and utilizing the MCST in addition to considering the various boundary conditions are the novelty of this study. Furthermore, the effects of length, thickness, FG power index, Winkler and Pasternak coefficients and shear correction factor on the natural frequency of double layer cylindrical FG microshell are studied.
    Keywords: double walled, Functionally graded material, moderately thick cylindrical microshell, Modified couple stress theory, Vibration Analysis
  • Ahad Gholipoor *, MohammadReza Shabgard, Mousa Mohammadpourfard, Hossein Abbasi Pages 45-64

    In this investigation, the material removal rate, tool wear rate and surface integrity obtained by EDM, ultrasonic vibrations assisted EDM and magnetic field assisted EDM were studied and compared with together to show the quality of the effects of applying each of ultrasonic vibrations to tool and magnetic field around gap distance of EDM process on material removal rate, tool wear rate, and surface integrity. According to the results, applying ultrasonic vibrations to tool electrode leads to an increase of 71% in material removal rate of EDM process while applying magnetic fields around gap distance of EDM process leads to an increase of 41% in material removal rate (of course in the best conditions). Also, applying magnetic fields around gap distance of EDM process leads to a decrease of 35% in surface roughness obtained by EDM process while the surface roughness of ultrasonic vibrations assisted EDM is higher than EDM process. Also, the created surface damages in the case of ultrasonic vibrations assisted EDM is the lowest and in the case of EDM process is the highest.

    Keywords: Ultrasonic Vibrations Assisted EDM, Magnetic Field Assisted EDM, Material Removal Rate, Tool Wear Rate, Surface quality
  • Saeed Amirkhani, Ali Chaibakhsh *, Ali Ghaffari Pages 65-86
    In this paper, ‎the multi-sensor fault diagnosis in the exhaust temperature sensors of a V94.2 heavy duty gas turbine is presented‎. ‎A Laguerre network-based fuzzy modeling approach is presented to predict the output temperature of the gas turbine for sensor fault diagnosis‎. Due to the nonlinear dynamics of the gas turbine, in these models the Laguerre filter parts are related to the linear dynamic part of the models and ‎the nonlinear parts of models are considered as neuro-fuzzy models. In order to deal with the dimensionality problems associated with fuzzy models‎, ‎the nonlinear parts of models are considered as hierarchical fuzzy systems. In the residual evaluation phase, model error modeling adaptive threshold approach is used to increase fault detection robustness against the noise and disturbance. A new expert fuzzy system by multi-sensor information fusion is presented for the fault diagnosis system‎, ‎which can examine the performance of all the sensors simultaneously‎. The result shows that the proposed fault diagnosis system could considerably increase reliability and safety‎.
    Keywords: Gas turbine engine‎, ‎Fault diagnosis‎, ‎Sensor‎, ‎Laguerre model‎, ‎Fuzzy system‎
  • Miralam Mahdi *, Vahid Sajjadi, Mohamad Rasekh Pages 87-109
    In this study, the effects of the volute tongue geometry variation on the head, efficiency, velocity distribution and cavitation structure of a centrifugal pump in the steady flow behavior under off-design conditions have been investigated. Numerical simulation modeling based on the  turbulence model with a hybrid grid is used to simulate the flow within the modeled pump. The flow is simulated by means of a commercial Computational Fluid Dynamics (CFD) software that solved the Reynolds-averaged Navier-Stokes (RANS) equations for a three-dimensional steady flow. The effects of thickness and angle of the tongue in various flow rates on the pump performance is investigated. Numerical results which are in well agreement with the experimental ones, show that the higher tongue angles caused an improvement on the head and efficiency of the pump especially in high flow rates. Investigations also indicate that the tongue thickness variations have no significant impact on the pump performance, although, the lower the thickness, the better the overall pump performance.
    Keywords: centrifugal pump, Cavitation, volute tongue, Computational fluid dynamics, Two-phase flow
  • Soheil Hashemi, AliAsghar Jafari * Pages 110-134

    In this paper, the nonlinear vibrations analysis of functionally graded (FG) rectangular plate in contact with fluid are investigated analytically using first order shear deformation theory (FSDT). The pressure exerted on the free surface of the plate by the fluid is calculated using the velocity potential function and the Bernoulli equation. With the aid of von Karman nonlinearity strain-displacement relations and Galerkin procedure the partial differential equations of motion are developed. The nonlinear equation of motion is then solved by modified Lindstedt-Poincare method. The effects of some system parameters such as vibration amplitude, fluid density, fluid depth ratio, volume fraction index and aspect ratio on the nonlinear natural frequency of the plate are discussed in detail.

    Keywords: Nonlinear vibration, Functionally graded materials, Fluid pressure, first order shear deformation theory, modified Lindstedt-Poincare method
  • MohammadMehdi Kheiri Khah *, A. Khodayari Pages 135-149

    The purpose of this paper is to design and optimize an intelligent fuzzy-logic controller for a three-degree of freedom (3DOF) artificial finger with shape-memory alloy (SMA) wire actuators. The robotic finger is constructed using three SMA wires as tendons to bend each phalanx of the finger around its revolute joint and three torsion springs which return the phalanxes to their original positions. A PID controller is designed to control the rotation of each phalanx. The gains of the controller are defined and optimized using the genetic algorithm. Finally, a fuzzy PID controller is presented to improve the performance of the system. The performance of the designed controller to achieve the desired output is simulated and also tested. The rotation of each link of both prototype robot and simulated model is measured. The experimental results show that the fuzzy controller can reach the desired angle in less time and the output signal is uniform. Moreover, the simulation results indicate that the closed-loop control system of the simulated robot is in good agreement with the prototype robot.

    Keywords: Optimization, genetic algorithm, artificial finger prototype, Fuzzy Controller, simlation