Iranian Society of Mechanical EngineeringIranian Journal of Mechanical Engineering Transactions of the ISME1605-972718220170901Introduced a Modified Set of Boundary Condition of Lattice Boltzmann Method Based on Bennett extension in Presence of Buoyancy Term Considering Variable Diffusion Coefficients52231830ENMostafa VarmazyarNo 40, Banafshe 9 Alley, Jahad Akbar Street,
35 metri lale Boulevard, Satari HighwayMohammadReza Habibi2Research Institute of Petroleum IndustryArash MohammadiShahid Rajaee Teacher Training UniversityJournal Article20161021Various numerical boundary condition methods have been proposed to simulate various aspects of the no-slip wall condition using the Lattice Boltzmann Method. In this paper, a new boundary condition scheme is developed to model the no-slip wall condition in the presence of the body force term near the wall which is based on the Bennett extension. The error related to the new model is smaller than those of other boundary condition methods existing in the last studies. Based on the computational results, the body forces method which representing minimum error has been illustrated. Finally, the effect of the variation of diffusion coefficients on Rayleigh-Benard convection was studied. The critical Rayleigh number, which is obtained by current method, are in good agreement with the results calculated by the linear stability theory. It has been revealed that the proposed model is capable of computing the effect of high nonlinearity in the conservative equation in the presence of variable diffusion coefficients.https://jmee.isme.ir/article_31830_7c5dc5d89bd0d2a1445a8a7beffbed56.pdfIranian Society of Mechanical EngineeringIranian Journal of Mechanical Engineering Transactions of the ISME1605-972718220170901Hollow Piezoelectric Cylinder under Transient Loads233831831ENMohsen JabbariIslamic Azad University South Tehran BranchMatin MousaviMechanical Engineering Department, South Tehran Branch, Azad University, IranMohammad AminKianiMechanical Engineering Department, South Tehran Branch, Azad University, IranJournal Article20170226In this paper, transient solution of two dimensional asymmetric thermal and mechanical stresses<br /> for a hollow cylinder made of piezoelectric material is developed. Transient temperature<br /> distribution, as function of radial and circumferential directions and time with general thermal<br /> boundary-conditions, is analytically obtained, using the method of separation of variables and<br /> generalized Bessel function. The results are the sum of transient and steady state solutions that<br /> depend upon the initial condition for temperature and heat source, respectively. The general<br /> form of thermal and mechanical boundary conditions is considered on the piezoelectric cylinder.<br /> Material properties of piezoelectric cylinder are the same along the thickness. A direct method<br /> is used to solve the Navier equations, using the Euler equation and complex Fourier series.https://jmee.isme.ir/article_31831_26dad38b7ad89d696ef83eb8ceffb9c0.pdfIranian Society of Mechanical EngineeringIranian Journal of Mechanical Engineering Transactions of the ISME1605-972718220170901Analysis of Multiple Yoffe-type Moving Cracks in an Orthotropic Half-Plane under Mixed Mode Loading Condition396231832ENMojtaba Mahmoudi MonfaredDepartment of Mechanical Engineering, Hashtgerd Branch, Islamic
Azad University, Alborz, Iran0000-0002-8894-0819Reza SourkiFaculty of Engineering, University of Zanjan, Zanjan, IranReza YaghoubiDepartment of Mechanical Engineering, University of Tarbiat Modares, Tehran, IranJournal Article20170727The present paper deals with the mixed mode fracture analysis of a weakened orthotropic half-plane with multiple cracks propagation. The orthotropic half-plane contains Volterra type glide and climb edge dislocations. It is assumed that the medium is under in-plane loading conditions. The distributed dislocation technique is used to obtain integral equations for the dynamic problem of multiple smooth cracks which are located in an orthotropic half-plane. At first, with the help of Fourier transform the dislocation problem is solved and the stress fields are obtained. The integral equations are of Cauchy type singularity and are solved numerically to obtain the dislocation densities on the surface of several cracks to determine the dynamic stress intensity factors on the crack tips. Several numerical examples are solved to evaluate mode I and mode II dynamic stress intensity factors to show the effects of the orthotropy parameters, crack lengths, and crack speed on the dynamic stress intensity factors.https://jmee.isme.ir/article_31832_36f3b28808bbd869c5646e0a016e443a.pdfIranian Society of Mechanical EngineeringIranian Journal of Mechanical Engineering Transactions of the ISME1605-972718220170901Cyclic Behavior of Beams Based on the Chaboche Unified Viscoplastic Model638131833ENVahid FalahiDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranHossein MahbadiDepartment of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran0000-0002-8080-5364Mohammad Reza EslamiAmirkabir University of Technology, Tehran, IranJournal Article20170901In this paper, ratcheting behavior of beams subjected to mechanical cyclic loads at elevated temperature, using the rate dependent Chaboche unified viscoplastic model with combined kinematic and isotropic hardening theory of plasticity, is investigated. A precise and general numerical scheme, using the incremental method of solution, is developed to obtain the cyclic inelastic creep and plastic strains. Applying the numerical method to the governing equations obtained based on the mentioned unified model, cyclic behavior of the beam due to the combined plastic and creep strains are obtained. Effect of loading rate, creep time, and mean load on ratcheting response and stress amplitude of the beam due to the combination of axial and bending moments at elevated temperatures are obtained. It is shown that increasing the loading rate, results into decrease in ratcheting rate and increase in stress amplitude. Also, the ratcheting strain increases with increasing the creep time while the stress amplitude decreases. The results obtained using the applied method in this paper is verified with the experimental data given in the literature search.https://jmee.isme.ir/article_31833_ebf55c90b945eb12c8b8cc6ca8e71eda.pdfIranian Society of Mechanical EngineeringIranian Journal of Mechanical Engineering Transactions of the ISME1605-972718220170901Interval-based Solar PV Power Forecasting Using MLP-NSGAII in Niroo Research Institute of Iran829431834ENMaryam KhademiDepartment of Applied Mathematics, Islamic Azad University South Tehran BranchAli NikookarPhD Student of Department of Computer Engineering, Islamic Azad University South Tehran Branch, Tehran, IranPooneh KhodabakhshM. Sc of Department of Computer Engineering, Islamic Azad University South Tehran Branch, Tehran IranMasoud MoadelPhD Student of Department of Energy Engineering, Islamic Azad University South Tehran Branch, Tehran,IranJournal Article20170926This research aims to predict PV output power by using different neuro-evolutionary methods. The proposed approach was evaluated by a data set, which was collected at 5-minute intervals in the photovoltaic laboratory of Niroo Research Institute of Iran (Tehran). The data has been divided into three intervals based on the amount of solar irradiation, and different neural networks were used for predicting each interval. NSGA II, a multi-objective optimization algorithm, has been applied to search an appropriate set of weights, which optimized the neural network with two or more conflicting objectives. The MLP-NSGA II algorithm provides better results with the Mean Square Error (MSE) and correlation coefficient (R2) of 0.01 and 0.98, respectively, in comparison with Linear Regression, MLP, and MLP-GA. By the way, obtained results show that the precision of prediction models would be improved by reducing input parameters’ time intervals.https://jmee.isme.ir/article_31834_15fa5a3c37ed711cddbc524af756dd2f.pdf