Search for: experimental-methods
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    An analytical and experimental study on dampening material effects on the dynamic behavior of free-free aluminum sheets

    , Article Engineering Solid Mechanics ; Volume 9, Issue 2 , 2021 , Pages 111-122 ; 22918744 (ISSN) Khorasani, R ; Hosseini Kordkheili, S. A ; Parviz, H ; Sharif University of Technology
    Growing Science  2021
    This work aims to present an experimentally verified analytical solution to examine damping properties of systems including viscoelastic treatments. Although there are several methods for characterizing the behavior of three-layer damping systems, the RKU method is the most frequently used one. In this paper, this method is modified such a way that to be applied for a five-layer damping system. The achieved analytical relations are then employed to study the effects of a four-layer vibration-absorbing coating on the dynamic behavior of an aluminum sheet with free-free boundary conditions. Since the vibration-damping properties of the coating are unknowns, its loss factor and shear modulus... 

    Numerical Investigation on Offshore wind Turbine Feasibility and Function

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Alireza (Author) ; Abbaspour Tehrani Fard, Madjid (Supervisor)
    This thesis consists of three main chapters. The first chapter is about describing principles about offshore wind turbine, principal concepts. This chapter also explains about advantages and disadvantages of installing wind turbine at offshore fields, and economical aspect of this kind of wind turbine farms. In the second chapter,anumerical method is used to investigate a SeaStar tension leg platform offshore wind turbine response behavior in parked condition. This code considers nonlinearities due to changes in tension of tethers. Wave forces are calculated adopting the Airy wave theory. Furthermore, shear turbulent wind is exerted on tower, with maximum speed 30 m/s on the hub. Since surge... 

    Carrying Capacity of Perforated Pipes in Submerged Area

    , M.Sc. Thesis Sharif University of Technology Nabaei, Milad (Author) ; Borghei, Mahmoud (Supervisor)
    Selective withdrawal from water and settlement reservoirs and tanks is necessary for water and environmental systems. Perforated pipes can be used for selective withdrawal within the length of these reservoirs. In this method, the lateral inflow through perforations leads to the outlet of the pipe that is placed in a depth of fluid. In relation to the hydraulics of perforated pipes, most studies are about drainage pipes and perforated pipes that are used as wellbores in horizontal wells, but application of these pipes have not been investigated in submerged situations. Capacity estimation of perforated pipes based on inside diameter of the pipe, material of the pipe, perforations of the... 

    Scale-up of Saturation Function in Composite Cores

    , M.Sc. Thesis Sharif University of Technology Mohammadi Alamouti, Amirhossein (Author) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Masihi, Mohsen (Co-Advisor)
    Water injection is one of the main methods of enhanced oil recovery that its success depends on exact study of main effective parameters. Saturation functions including relative permeability function and capillary pressure function are one of the effective parameters on the success of water injection projects. In many reservoirs there is wide heterogeneity and various layering that have different absolute permeability. These features result in uncertainty to measurement of curves of saturation function. Experimental studies on this field are carried out on the composite cores that show heterogeneity and layering media of reservoir. By Scaling up the saturation functions from single cores to... 

    An approach for the estimation of dynamic imbibition capillary pressure curves

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 9 , Dec , 2010 , p. 1007-1017 ; ISSN: 15567036 Shojaadini Ardakany, M ; Shadizadeh, S.R ; Masihi, M ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    Capillary pressure is one of the most important parameters for reservoir engineering studies. Although different experimental methods are devised to measure capillary pressure, these methods do not represent the physics of fluid flow, which happens at reservoir conditions. Thus, it is attempted to extract the capillary pressure from spontaneous imbibition data, the common mechanism of oil production in water wet porous media. In this work, a new approach is developed to obtain the imbibition capillary pressure curve by using spontaneous water imbibition data in oil-water-rock systems. Comparison of calculated imbibition capillary pressure curves by the new approach with experimental values... 

    An experimental study of interceptor's effectiveness on hydrodynamic performance of high-speed planing crafts

    , Article Polish Maritime Research ; Volume 20, Issue 2 , 2013 , Pages 21-29 ; 12332585 (ISSN) Karimi, M. H ; Seif, M. S ; Abbaspoor, M ; Sharif University of Technology
    Trim control mechanisms such as interceptors and trim flaps have been widely used in recent years in highspeed crafts for ride and trim control. In spite of their extensive application, a few studies investigating the impact of interceptors on planing craft performance, have been published. In the present study, the impact of interceptors on planing crafts hydrodynamic quality is investigated through application of an experimental method. Two scaled-down models of high-speed planing mono-hull and catamaran are tested with and without interceptors in calm water at different heights of the interceptors to investigate the effect of interceptors on drag reduction of the models. The first one is... 

    Clearance effects on dynamic behavior of a continuous mechanical system

    , Article JVC/Journal of Vibration and Control ; Volume 21, Issue 13 , October , 2015 , Pages 2509-2519 ; 10775463 (ISSN) Hosseini Kordkheili, S. A ; Momeni Massouleh, S. H ; Khorasani, R ; Sharif University of Technology
    SAGE Publications Inc  2015
    An analytical modified method is presented to investigate the clearance effects on the dynamic behavior of cantilever beams. In this work, apart from clearance, all other nonlinearities are avoided to be considered during the analytical solution. The beam is idealized using an equivalent single-degree-of-freedom structure. A tri-linear stiffness system is also adopted to simulate the beam together with the clearance. Subsequently the analytical solution is derived for a cantilever beam structure with and without considering structural damping. The experimental method is employed to verify the results from the presented analytical solutions. It is noted that the results obtained by the... 

    Dynamic Analysis of Structure with Modal Properties Identification of Its Substructures Using Component Mode Synthesis

    , M.Sc. Thesis Sharif University of Technology Momeni Massoule, Hassan (Author) ; Hosseini Kordkheili, Ali (Supervisor)
    The substructuring method provides a suitable tool to conduct modal analysis of large and complicated structures. In this method the original structure is decomposed into simpler and smaller substructures, and the dynamic properties of the resulting substructures are first evaluated independently. The original structure’s dynamic properties are subsequently estimated by coupling the substructures’ dynamic results. In this procedure, the boundary conditions need to be imposed in such a way that the overall behaviour of the original structure is properly represented. Substructuring method can be used in different types of dynamic analysis. The focus of this paper is on the modal type of... 

    Screening of the EOR Scenarios for Shaly Heavy Oil Reservoirs Using Five-Spot Glass Micromodel: an Experimental Study

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Saber (Author) ; Masihi, Mohsen (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Kharrat, Riyaz (Supervisor)
    Most of the heavy oil reservoirs contain discontinuous shaly structures which affect fluid flow through porous media as well as oil recovery efficiency during EOR processes. However, selecting the best EOR technique which maximizes the oil recovery remains a topic of debate in the literature. In addition the effect of shale geometrical characteristics including: spacing from wells, discontinuity, orientation, number of shale streaks, shale's spacing and length on oil recovery factor are not well understood. In this work experiments have been performed on one-quarter five-spot glass micromodels. These models have been developed by a new method using laser technology. Generally, this research... 

    Experimental Investigation of the Displacement Efficiency of Surfactant Flooding in Fractured Porous Medium Using One-Quarter Five Spot Micromodel

    , M.Sc. Thesis Sharif University of Technology Kianinejad, Amir (Author) ; Rashtchian, Davood (Supervisor) ; Kharraat, Riaz (Supervisor) ; Ghazanfari, Mohammad (Supervisor)
    Naturally fractured oil reservoirs represent over 20% of the world's oil reserves, while over 60% of the world’s remaining oil lies trapped in fractured reservoirs. However, relatively little success has been achieved in increasing oil production from these complex reservoirs. Water flooding process leaves much oil in the reservoir, especially in fractured reservoirs. Surfactant flooding is known to lower the interfacial tension and hence, reduces capillary forces responsible for trapping oil and increasing recovery. However, fundamental understanding how the fracture geometrical properties affect the oil recovery efficiency during surfactant flooding remains a topic of debate in the... 

    Accuracy and Stability Properties of the Numerical Integration Method with Combined Implicit or Explicit Steps for Use in Hybrid Simulations

    , M.Sc. Thesis Sharif University of Technology Abi, Amir Reza (Author) ; Ahmadizadeh, Mehdi (Supervisor)
    The increased need for experimental verification of the seismic performance of conventional and novel structural systems has resulted in highly sophisticated dynamic test procedures. Hybrid simulation is one of the most efficient experimental methods for assessment of dynamic and rate-dependent behavior of large-scale structural systems under earthquake excitation. Compared to earthquake simulations using shake tables, hybrid simulation may have significant advantages in terms of cost, scale, geometry, and required physical mass of structures. However, recent hybrid simulations have been limited to simplified structural models with only a few degrees of freedom. Currently, the major... 

    Effects of Employing Vibro Absorbing Coating on Vibration Behavior of a Stiffened Panel

    , M.Sc. Thesis Sharif University of Technology Khorasani, Reza (Author) ; Hosseini Kordkheili, Ali (Supervisor)
    In this thesis the effects of vibro absorbing coating on vibration behavior of an aluminum sheet and also on a stiffened aluminum panel are investigated using experimental approach. Since there wasn't any information available about the used coating, to find its viscoelastic material properties, the method mentioned in ASTM E756-05 standard is employed and corresponding tests are performed.
    In the next step, an analytical solution developed for the aluminum sheet with viscoelastic coating and the obtained results compared with experimentation, in order to find its prediction accuracy for loss in “loss factor” of the system in presence of coating.
    To study the effect of... 

    Applying a robust solution based on expert systems and GA evolutionary algorithm for prognosticating residual gas saturation in water drive gas reservoirs

    , Article Journal of Natural Gas Science and Engineering ; Vol. 21, issue , November , 2014 , p. 79-94 Tatar, A ; Yassin, M. R ; Rezaee, M ; Aghajafari, A. H ; Shokrollahi, A ; Sharif University of Technology
    In strong water drive gas reservoirs (WDGRs), the water encroachment in the gas zone has adverse effects on the gas mobility and causes considerable volume of gas to be trapped behind water front; therefore estimation of residual gas saturation after water influx is an important parameter in estimation of gas reservoirs with strong aquifer support. It is difficult to achieve a thorough and exact understanding of water drive gas reservoirs. It depends on several parameters of petrophysical and operational features. In majority of the previous studies about residual gas saturation, the correlations were depended on petrophysical properties such as porosity, permeability, and initial gas... 

    Experimental dynamic modelling of peripheral milling with process damping, structural and cutting force nonlinearities

    , Article Journal of Sound and Vibration ; Volume 332, Issue 19 , 2013 , Pages 4709-4731 ; 0022460X (ISSN) Moradi, H ; Vossoughi, G ; Movahhedy, M. R ; Sharif University of Technology
    In this paper, an extended dynamic model of peripheral milling process including process damping, structural and cutting force nonlinearities is presented. Cutting forces are described through a third-order polynomial function of chip thickness while a cubic nonlinear function is considered for the structural stiffness. Under stable and regenerative chatter conditions and using Fourier series components, closed form expressions for the nonlinear cutting forces are derived. Parameters of the proposed model are identified through a set of experiments. For this purpose, modal experiments and measurement of cutting forces (at various feed rates) are performed to determine the modal parameters... 

    Design and implementation of a new spherical super element in structural analysis

    , Article Applied Mathematics and Computation ; Volume 218, Issue 14 , March , 2012 , Pages 7546-7561 ; 00963003 (ISSN) Sarvi, M. N ; Ahmadian, M. T ; Sharif University of Technology
    Finite Element Method (FEM) has proved to be a powerful tool for the analysis of mechanical problems such as finding natural frequency and deformation of structures. Design and implementation of super elements with a purpose in reduction of computational time along with accuracy is one of the challenges facing engineers in the past decade. In this study a newly spherical super element is designed and implemented to some problems. This element is generated in such a way that the user can select as many numbers of nodes as desired. Proper formulation is presented to generate the shape function for each node in this element. Some examples of static and vibration analysis using this element are... 

    An exact Analytical solution to exponentially tapered piezoelectric energy harvester

    , Article Shock and Vibration ; Volume 2015 , 2015 ; 10709622 (ISSN) Salmani, H ; Rahimi, G. H ; Hosseini Kordkheili, S. A ; Sharif University of Technology
    Hindawi Publishing Corporation  2015
    It has been proven that tapering the piezoelectric beam through its length optimizes the power extracted from vibration based energy harvesting. This phenomenon has been investigated by some researchers using semianalytical, finite element and experimental methods. In this paper, an exact analytical solution is presented to calculate the power generated from vibration of exponentially tapered unimorph and bimorph with series and parallel connections. The mass normalized mode shapes of the exponentially tapered piezoelectric beam with tip mass are implemented to transfer the proposed electromechanical coupled equations into modal coordinates. The steady states harmonic solution results are... 

    Calculation and measurement of kinetics parameters of Tehran research reactor

    , Article International Conference on Nuclear Engineering, Proceedings, ICONE, 12 July 2009 through 16 July 2009, Brussels ; Volume 5 , 2009 , Pages 223-228 ; 9780791843550 (ISBN) Hosseini, S. A ; Vosoughi, N ; Gharib, M ; Ghofrani, M. B ; Sharif University of Technology
    Effective delayed neutron fraction βeff and neutron generation time Λare important factors in reactor physics calculation and transient analysis. In first stage of this research, these kinetics parameters have been calculated for two states of Tehran research reactor (TRR), i.e. cold (fuel, clad and coolant temperature 20°C) and hot (fuel, clad and coolant temperature 65, 49 and 44°C, respectively) using MTR-PC code. In second stage, these parameters have been measured with experimental method based on Inhour equation. For cold state, calculated βeff and Λ by MTR-PC are 0.008315 and 30.190 μsec, respectively. Same parameters in hot state are 0.008303 and 33.828 μsec, respectively. The... 

    A new investigation of wax precipitation in iranian crude oils: Experimental method based on FTIR spectroscopy and theoretical predictions using PC-SAFT model

    , Article Journal of Molecular Liquids ; Volume 249 , 2018 , Pages 970-979 ; 01677322 (ISSN) Mashhadi Meighani, H ; Ghotbi, C ; Jafari Behbahani, T ; Sharifi, Kh ; Sharif University of Technology
    Elsevier B.V  2018
    Temperature dependency of infrared band intensity for methylene rocking vibration could be used as indication for creation of solid crystals while decreasing temperature. In this work, different experiments were conducted to measure wax appearance temperature, WAT, such as cross polarized microscopy, rheometry and FTIR spectroscopy. Three Iranian crude oils were characterized based on the SARA test and PC-SAFT model was developed to predict WAT. The obtained results by FTIR spectroscopy and PC-SAFT model were in quite agreement. FTIR spectroscopy determined higher WAT values which may be due to its higher sensitivity to smaller wax crystals. Also, the effect of a polymeric crystal modifier... 

    High-frequency random vibrations of a stiffened plate with a cutout using energy finite element and experimental methods

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 234, Issue 16 , 2020 , Pages 3297-3317 Nokhbatolfoghahai, A ; Navazi, H. M ; Haddadpour, H ; Sharif University of Technology
    SAGE Publications Ltd  2020
    In this paper, by employing the energy finite element analysis, the high-frequency vibrations of a stiffened plate having a cutout, subjected to random vibrations, have been analyzed, and the obtained results have been validated by use of experimental methods. By using equations for joining of structures, energy finite element analysis computer codes were developed for the coupling of beam-plate elements. Finally, a plate containing a cutout and three stiffeners was fabricated and subjected to high-frequency random vibration tests. The results of the prepared codes were compared with the results of experiments. These comparisons indicated that at high frequencies, the energy finite element... 

    Analytical model of the electro-mechanical impedance response of frame structures with L-shaped beams

    , Article Research in Nondestructive Evaluation ; Volume 31, Issue 3 , 2 January , 2020 , Pages 187-202 Mohsenzadeh, M ; Hamzeloo, S. R ; Barzegar, M ; Pourkamali Anaraki, A ; Sharif University of Technology
    Taylor and Francis Inc  2020
    The electro-mechanical impedance (EMI) method has been accepted as an effective technique for detecting damages in the Structural health monitoring (SHM). EMI at any point of the structure depends on material properties, geometry and boundary conditions that all appears in dynamic stiffness of the structure. In spite of the expensive experimental methods for measuring the mechanical impedance, or the cheaper one electromechanical impedance, of structures, various analytical methods could be substitutions for them. In this paper, an analytical method is developed to obtain the EMI response of L-shaped beams through calculating the dynamic stiffness of the structure. To verify the model, an...