فهرست مطالب

Iranian Journal of Mechanical Engineering Transactions of ISME
Volume:13 Issue: 2, Sep 2012

  • تاریخ انتشار: 1391/11/15
  • تعداد عناوین: 6
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  • Instruction for the Preparation of Camera-Ready Papers
    Pages 1-4
  • M.M. Rashidi *, A. Hajipour, A. Fahimirad Pages 5-19
    There are heat losses during the cycle of real engine that are neglected in ideal air-standard analysis. In this paper, the effect of heat transfer on the net output work is shown and thermal efficiency of the air-standard Atkinson and the Dual combustion cycles are analyzed. Comparison of performances of the airstandard Atkinson and the Dual combustion cycles with heat transfer considerations are also discussed. We assumed that the compression and power processes are adiabatic and reversible and any convective, conductive and radiative heat transfer to cylinder wall during the heat rejection process may be ignored. The heat loss through the cylinder wall is assumed to occur only during combustion and is further assumed to be proportional to average temperature of both the working fluid and cylinder wall. The results show that the net work output versus efficiency and the maximum net work output and corresponding efficiency bounds are influenced by the magnitude of heat transfer. The results are of importance to provide guidance for the performance evaluation of practical engines.
    Keywords: Thermodynamics, Efficiency, Atkinson cycle, Dual combustion cycle, Heat transfer
  • M. Tavakolian*, A.A. Jafari, S.M.R. Khalili Pages 20-34
    In this paper, the nonlinear vibration of functionally graded (FGM) cylindrical shells subjected to radial harmonic excitation is investigated. The nonlinear formulation is based on a Donnell’s nonlinear shallow-shell theory, in which the geometric nonlinearity takes the form of von Karman strains. The Lagrange equations of motion were obtained by an energyapproach. In order to reduce the system to finite dimensions, the middle surface displacements were expanded by using trial functions. These functions were expressed in terms of Fourier series containing linear mode shapes, which were obtained from free vibration analysis. The large-amplitude response and amplitude frequency curves of shell were computed by using numerical method for both linear and nonlinear analysis.
    Keywords: nonlinear vibration, functionally graded, harmonic load
  • H. Mahbadi* Pages 35-58
    Elastic-plastic behavior of a beam made of functionally graded mate- rial is investigated in this work. The beam is subjected to the constant axial and bending loads and the critical values of these loads for yield, collapse and elastic-plastic conditions are obtained. The variation of elastic modulus and yield strength through the height of the beam is determined with an exponential rule. The perfect plastic curve is used to model the plastic behavior of the beam. The interaction diagrams between the bending moment and axial load are obtained for both of the yield and collapse conditions. The effect of power law function on yield and collapse loads is estimated. The results are reduced to the homogeneous beam and validated with data given in the literature search.
    Keywords: FGM, Collapse load, Yield load, Mechanical load, Plastic analysis, Beam
  • F. Ahmadi Boyaghchi* Pages 59-80
    A thermodynamic analysis of an operational 315 MW supercritical steam power plant (SPP) using the actual data is performed to assess the plant performance and identify the sites of energy losses and exergy destructions in each component of the plant. Various performance parameters such as component energy and exergy efficiencies, energy loss rate, exergy destruction rate, improvement potential (IP) rate and different plant efficiencies based on first and second thermodynamic laws were calculated and compared. Also, a parametric study is performed to investigate the effects of various turbine system operating conditions such as high pressure turbine (HPT) inlet pressure, HPT inlet temperature, intermediate pressure turbine (IPT) inlet pressure, HPT inlet temperature, and IPT inlet mass flow rate on plant efficiencies and exergy destruction of plant components.
    Keywords: energy, exergy, sensitive study, steam power plant
  • M. Kordbacheh*, A. Yousefi, Koma Saleh, M.H. Soorgee Pages 81-95
    A Lamb wave-based crack detection method for aluminum plates health monitoring is developed in this paper. Piezoelectric disks are employed to actuate and capture the Lamb wave signals. The position of crack is assumed to be aligned with the sensor and actuator. Extraction of high quality experimental results of lamb wave propagation in a plate-like structure is considerably complicated due to phenomena such as multimode excitation, wave dispersion, material attenuation, and boundary reflection. The main goal of this study is to utilize a customized wavelet transform technique to purify the captured Lamb wave signals. Significant features of these signals were then extracted from the wave energy distribution. Experimental results show that the developed method has a promising capability in identification of crack positions.
    Keywords: Lamb Waves, Wavelet Transform, Damage Identification