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Total 22 records

    Position error calculation of linear resolver under mechanical fault conditions

    , Article IET Science, Measurement and Technology ; Volume 11, Issue 7 , 2017 , Pages 948-954 ; 17518822 (ISSN) Daniar, A ; Nasiri-Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
    Abstract
    Position sensors are inseparable part of motion control systems. Linear resolvers (LRs) are electromagnetic position sensors that are suitable for high vibration, polluted environments. The accuracy of their detected position can be affected by different mechanical faults. In this study, variety of possible mechanical faults along with their mathematical index in LRs is introduced. Static eccentricity, dynamic eccentricity, inclined mover and run out error are the presented mechanical faults that are discussed independently and simultaneously. Then, three-dimensional non-linear, time-stepping finite element method is employed to investigate the performance of the studied resolver under... 

    Analytical model for performance prediction of linear resolver

    , Article IET Electric Power Applications ; Volume 11, Issue 8 , 2017 , Pages 1457-1465 ; 17518660 (ISSN) Saneie, H ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
    Abstract
    In this study an analytical model based on solving Maxwell equations in the machine layers is presented for linear resolver (LR). Anisotropy, field harmonics, slot effects, number of slots per pole per phase and the effect of tooth skewing are considered in the model. The proposed method is a design oriented technique that can be used for performance prediction and design optimisation of the LR due to its acceptable accuracy and fast computation time. Two- and three-dimensional time stepping finite element method (FEM) is employed to validate the results of the proposed model. Good correlations between the results obtained by the proposed method and the FEM confirm the superiority of the... 

    Numerical modeling of die filling of semi-solid A356 aluminum alloy

    , Article Semi-Solid Processing of Alloys and Composites 10 - Selected, peer reviewed papers from the 10th International Conference on Semi-Solid Processing of Alloy and Composites, S2P 2008, Aachen, 16 September 2008 through 18 September 2008 ; Volume 141-143 , 2008 , Pages 605-610 ; 10120394 (ISSN); 9771012039401 (ISBN) Foroughi, A ; Aashuri, H ; Narimannezhad, A ; Khosravani, A ; Kiani, M ; Sharif University of Technology
    Trans Tech Publications Ltd  2008
    Abstract
    Computer base and simulation technique have been applied for modeling the semi-solid die filling and part of the solidification process of aluminum A356 alloy. A fairly simple one-phase rheological model has been implemented into a fluid flow finite element software Procast, to solve the partial differential equations. This model is purely viscous nature and is implemented in the power law cut-off model of Procast. The constitutive parameters of this model were determined for a rheocast A356 alloy. Using these parameters and comparing the simulation results with experimental data showed good correlation with the model prediction. The designed die for rheocasting was applied for the... 

    Numerical modeling and experimental validation of microstructure in gray cast iron

    , Article International Journal of Minerals, Metallurgy and Materials ; Volume 19, Issue 10 , 2012 , Pages 908-914 ; 16744799 (ISSN) Jabbari, M ; Davami, P ; Varahram, N ; Sharif University of Technology
    Springer  2012
    Abstract
    To predict the amount of different phases in gray cast iron by a finite difference model (FDM) on the basis of cooling rate (R), the volume fractions of total γphase, graphite, and cementite were calculated. The results of phase composition were evaluated to find a proper correlation with cooling rate. More trials were carried out to find a good correlation between the hardness and phase composition. New proposed formulas show that the hardness of gray cast iron decreases as the amount of graphite phase increases, and increases as the amount of cementite increases. These formulas are developed to correlate the phase volume fraction to hardness. The results are compared with experimental data... 

    Energy absorption mechanism of Alsteel bilayer sheets produced by cold roll welding during wedge tearing

    , Article International Journal of Mechanical Sciences ; Volume 52, Issue 12 , December , 2010 , Pages 1613-1619 ; 00207403 (ISSN) Beygi, R ; Kazeminezhad, M ; Sharif University of Technology
    2010
    Abstract
    The behavior of Alsteel bilayer sheets produced by cold roll welding is investigated through the wedge tearing process. It is observed that through tearing the energy absorbed by cold roll welded bilayer sheets is larger than that of non-welded ones, even though all parameters are identical. Also bilayer sheets with low bond strength have the same energy absorbed by non-welded bilayer sheets. By investigating all contributing mechanisms in tearing and mechanical properties of composite layers and developing theoretical equations, it is concluded that bending of sheets through wedge tearing plays a major role in difference of energy absorbed by welded and non-welded bilayer sheets. Moreover,... 

    Dynamic simulation of the biped normal and amputee human gait

    , Article Mobile Robotics: Solutions and Challenges - Proceedings of the 12th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2009, 9 September 2009 through 11 September 2009, Istanbul ; 2010 , Pages 1113-1120 ; 9814291269 (ISBN) ; 9789814291262 (ISBN) Shandiz, M. A ; Farahmand, F ; Zohour, H ; Sharif University of Technology
    2010
    Abstract
    A two-dimensional seven link biped dynamic model was developed to investigate the mechanical characteristics of the normal and amputee locomotion during the complete gait cycle. The foot-ground contact was simulated using a five-point penetration contact model. The equations of motion were derived using Lagrange method. Optimization of the normal human walking model provided constant coefficients for the driving torque equations that could reasonably reproduce the normal kinematical pattern. The resulting torques were then applied to the intact joints of the amputee model with a prosthetic leg equipped with a kinematical driver controller for the ankle and either a hydraulic, elastic or... 

    Geometric parameters and response surface methodology on cooling performance of vortex tubes

    , Article International Journal of Sustainable Energy ; 2016 , Pages 1-15 ; 14786451 (ISSN) Nouri borujerdi, A ; Bovand, M ; Rashidi, S ; Dincer, K ; Sharif University of Technology
    Taylor and Francis Ltd 
    Abstract
    This research has investigated the effect of certain geometric parameters on cooling performance of three vortex tubes. The influencing parameters include three length/diameter ratios L/D = 10, 25, 40, three nozzle cases and each case with number n = 2, 4, 6 nozzles, three cold orifice/diameter ratios β = 0.389, 0.5, 0.611 and three inlet pressures Pi = 2, 2.5 and 3 bar. The experiments are conducted based on three factors, two-level and central composite face-centred design with full factorial. The results are analysed according to the principle of response surface methodology. The goodness of fit of the regression model is inspected using the analysis of variance and F-ratio test. The... 

    Experimental and numerical survey on tensile fracture of polycrystalline graphite using design of experiments

    , Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 230, Issue 1 , 2016 , Pages 151-159 ; 14644207 (ISSN) Shakouri, M ; Khodadad, A ; Rezaeibana, R ; Sharif University of Technology
    SAGE Publications Ltd 
    Abstract
    A new test specimen for a tensile test of industrial graphite is introduced using experiment and finite element results. The most influencing factors on the tensile strength of the test specimens are considered and the number of tests, which are necessary to optimize the tensile strengths are reduced based on the design of experiment using the Taguchi method and the effects of all factors on strength of test samples are studied. Comparison of the predicted strengths based on the Taguchi approach with the measured experimental results and finite element analysis shows a good correlation between them. In addition, results show that the new introduced specimen makes a 33% increase in the... 

    Characterization of anisotropic behaviour of ZK60 extrusion under stress-control condition and notes on fatigue modeling

    , Article International Journal of Fatigue ; Volume 127 , 2019 , Pages 101-109 ; 01421123 (ISSN) Pahlevanpour, A. H ; Behravesh, S. B ; Adibnazari, S ; Jahed, H ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The anisotropic fatigue behavior of ZK60 is investigated through stress-control tests along two different material directions: extrusion (ED) and radial (RD) directions. The in-plane random texture along RD promotes activation of twinning/detwinning deformations in both tension and compression reversals, which brings about a sigmoidal but near-symmetric shape for hysteresis loops. The stress-strain response along ED is asymmetric, which is attributed to different deformation mechanisms in tension and compression reversals. The higher fatigue strength along ED is related to lower plastic strain energy in this direction. An energy damage parameter showed a good correlation with tests performed... 

    The effect of filler type and content on rutting resistance of asphaltic materials

    , Article International Journal of Pavement Research and Technology ; Volume 12, Issue 3 , 2019 , Pages 249-258 ; 19966814 (ISSN) Hamidi, A ; Motamed, A ; Sharif University of Technology
    Springer  2019
    Abstract
    This research evaluates the effect of filler type and content on rutting resistance of asphaltic materials by using laboratory experiments. To examine the effect of filler type, two traditional fillers (Silica sandstone powder and Portland cement) and a new recycled lime powder (Eggshell) were considered. To investigate the effect of filler content, three different filler contents were used. Marshall Stability test was performed on full mixes in order to determine the optimum binder content of the mixtures. Then, the static creep test was performed on Fine Aggregate Matrix (FAM) samples. The permanent strain after 10 minutes of recovery (PS-660) was considered as the indicator of potential... 

    Analytical and numerical biaxial bending analysis of deepwater riser due to vortex-induced vibration

    , Article Journal of Marine Science and Technology (Japan) ; 2021 ; 09484280 (ISSN) Tabeshpour, M. R ; Komachi, Y ; Sharif University of Technology
    Springer Japan  2021
    Abstract
    Previous studies of analysis and prediction of marine risers responses usually focus on vortex-induced vibration (VIV) of cross-flow (CF) direction rather than in-line (IL). Recent studies show that responses of IL direction tend to dominate in some cases. Responses of long riser due to biaxial bending of IL and CF VIV are investigated. Closed-form formulas are derived for estimating maximum normal stress due to the biaxial moment of CF/IL VIV and relations for estimating biaxial stress using CF values are presented. Analytical results are compared with numerical results of the time domain model and a good correlation is observed. It is shown that for tension and bending-controlled modes of... 

    Experimental study on cyclic behavior of trapezoidally corrugated steel shear walls

    , Article Engineering Structures ; Volume 48 , March , 2013 , Pages 750-762 ; 01410296 (ISSN) Emami, F ; Mofid, M ; Vafai, A ; Sharif University of Technology
    2013
    Abstract
    This paper presents the research works on the cyclic behavior of trapezoidally corrugated as well as unstiffened steel shear walls. A series of experimental studies were carried out on the half-scale, one-story, single-bay steel shear walls with unstiffened and trapezoidally corrugated panels. This experimental study was conducted to compare the stiffness, strength, ductility ratio and energy dissipation capacity of three different steel shear walls: unstiffened, trapezoidally vertical corrugated and trapezoidally horizontal corrugated. Gravity loads were not applied at the top of the walls and horizontal load was applied at the top of each specimen. Loading sequence was applied as... 

    Neural network prediction of mechanical properties of porous NiTi shape memory alloy

    , Article Powder Metallurgy ; Volume 54, Issue 3 , Nov , 2011 , Pages 450-454 ; 00325899 (ISSN) Parvizi, S ; Hafizpour, H. R ; Sadrnezhaad, S. K ; Akhondzadeh, A ; Abbasi Gharacheh, M ; Sharif University of Technology
    2011
    Abstract
    A multilayer back propagation learning algorithm was used as an artificial neural network tool to predict the mechanical properties of porous NiTi shape memory alloys fabricated by press/sintering of the mixed powders. Effects of green porosity, sintering time and the ratio of the average Ti to Ni particle sizes on properties of the product were investigated. Hardness and tensile strength of the compacts were determined by hardness Rockwell B method and shear punch test. Three-fourths of 36 pairs of experimental data were used for training the network within the toolbox of the MATLAB software. Porosity, sintering time and particle size ratios were defined as the input variables of the model.... 

    Comparative studies of some heterocyclic compounds as corrosion inhibitors of copper in phosphoric acid media

    , Article Chemical Engineering Communications ; Volume 197, Issue 10 , 2010 , Pages 1303-1314 ; 00986445 (ISSN) Lashgari, M ; Arshadi, M. R ; Biglar, M ; Sharif University of Technology
    2010
    Abstract
    Corrosion inhibition properties of some heterocyclic compounds (3-mercapto 1,2,4 triazole, benzotriazole, thiophene, and tetra hydro-thiophene) in Cu/H3PO4 medium were investigated theoretically and experimentally via cluster/polarized continuum and gravimetric approaches. Second-order Møller-Plesset perturbation and density functional theories were applied, and the electronic chemical potential, molecular softness, and extent of charge transfer were determined for inhibitor molecules at the metal/solution interface. Good correlations were observed for both theories between the calculated quantities and experimental data. To reveal the quality of metal-inhibitor interactions, comprehensive... 

    Identification of fluid dynamics in forced gravity drainage using dimensionless groups

    , Article Transport in Porous Media ; Volume 83, Issue 3 , July , 2010 , Pages 725-740 ; 01693913 (ISSN) Rostami, B ; Kharrat, R ; Pooladi Darvish, M ; Ghotbi, C ; Sharif University of Technology
    2010
    Abstract
    A number of forced gravity drainage experiments have been conducted using a wide range of the physical and operational parameters, wherein the type, length, and permeability of the porous medium as well as oil viscosity and injection rate were varied. Results indicate that an increase in the Bond number has a positive effect on oil recovery whereas the capillary number has an opposite effect. These trends were observed over a two-order of magnitude change in the value of the dimensionless groups. Furthermore, it was found that use of each number alone is insufficient to obtain a satisfactory correlation with recovery. A combined dimensionless group is proposed, which combines the effect of... 

    Nonlinear identification of electro-magnetic force model

    , Article Journal of Zhejiang University: Science A ; Volume 11, Issue 3 , 2010 , Pages 165-174 ; 1673565X (ISSN) Shabani, R ; Tariverdilo, S ; Salarieh, H ; Sharif University of Technology
    2010
    Abstract
    Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses, flux leakage or saturation of iron. In this paper, based on results from an experimental set-up designed to study magnetic force, a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients. The parameters of the proposed model are identified using the weighted residual method. Validations of the model identified were performed by comparing the results in time and frequency domains. The results show a good... 

    Permeability modeling using ANN and collocated cokriging

    , Article 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 ; Volume 5 , 2010 , Pages 3939-3943 ; 9781617386671 (ISBN) Zarei, A ; Masihi, M ; Sharif University of Technology
    Society of Petroleum Engineers  2010
    Abstract
    Obtaining a reliable reservoir permeability map that is consistent with all available data is of great important for reservoir engineers. However, there is not enough core from existing wells to estimate the reservoir permeability directly but Well log data are more widely available. This study aims to model permeability within the reservoir while there is no enough data. In particular, we use artificial neural networks to estimate permeability using four input logs of sonic, gravity, porosity and neutron logs in six existing wells. In order to eliminate the correlated data, we have done Principal Component Analysis on selected input logs. Collocated cokriging is considered as a valuable... 

    Geometric parameters and response surface methodology on cooling performance of vortex tubes

    , Article International Journal of Sustainable Energy ; Volume 36, Issue 9 , 2017 , Pages 872-886 ; 14786451 (ISSN) Nouri Borujerdi, A ; Bovand, M ; Rashidi, S ; Dincer, K ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    Abstract
    This research has investigated the effect of certain geometric parameters on cooling performance of three vortex tubes. The influencing parameters include three length/diameter ratios L/D = 10, 25, 40, three nozzle cases and each case with number n = 2, 4, 6 nozzles, three cold orifice/diameter ratios β = 0.389, 0.5, 0.611 and three inlet pressures Pi = 2, 2.5 and 3 bar. The experiments are conducted based on three factors, two-level and central composite face-centred design with full factorial. The results are analysed according to the principle of response surface methodology. The goodness of fit of the regression model is inspected using the analysis of variance and F-ratio test. The... 

    Experimental and numerical fatigue life study of cracked AL plates reinforced by glass/epoxy composite patches in different stress ratios

    , Article Mechanics Based Design of Structures and Machines ; Volume 49, Issue 6 , 2021 , Pages 894-910 ; 15397734 (ISSN) Hosseini, K ; Safarabadi, M ; Ganjiani, M ; Mohammadi, E ; Hosseini, A ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    In this study, the fatigue behavior of composite reinforced cracked aluminum 1050 plates is investigated experimentally and numerically. The tests are conducted in four different stress ratios between 0 and 1. At first step, plates with similar cracks and geometries have been prepared. Then the glass/epoxy patches have been attached to the cracked plates using Araldite 2015 adhesive. Fatigue load has been applied to three cases of samples including non-patch, one-side patch and two-side patch, where in all stress ratios the maximum force is considered constant. A three-dimensional finite element analysis is developed in ABAQUS. A good correlation between finite element results and the... 

    Study of shape memory effect in NiMnGa Magnetic Shape Memory Alloy single crystals by incremental modeling

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 1 , 2010 , Pages 441-446 ; 9780791849156 (ISBN) Khajehsaeid, H ; Naghdabadi, R ; Sohrabpour, S ; Sharif University of Technology
    Abstract
    Magnetic Shape Memory Alloys (MSMAs) are a category of active materials which can be excited by magnetic field. These alloys have been used in sensor and actuator applications recently. MSMAs possess special properties such as large magnetic field-induced strains (up to %10) and high actuation frequency (about 1kHz), while ordinary shape memory alloys can't act in frequencies above 5Hz due to the time involved with heat transformation. In this paper, MSMAs are modeled by an incremental modeling approach which utilizes different secant moduli for different parts of stress-strain curve. Furthermore, stress-strain curve of MSMAs is approximated using an analytical expression. The incremental...