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    Analysis and modification of a common energy harvesting system using magnetic shape memory alloys

    , Article Journal of Intelligent Material Systems and Structures ; Volume 32, Issue 5 , 2021 , Pages 568-583 ; 1045389X (ISSN) Sayyaadi, H ; Mehrabi, M ; Hoviattalab, M ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Abstract
    In this paper, a common energy harvester is investigated which uses a specimen of magnetic shape memory alloy (MSMA). The aim of this study is to improve system performance and to evaluate the magneto-mechanical loading on the MSMA material. Since demagnetization effect is not included in the employed original MSMA model, a method to incorporate this effect is proposed which has a good performance for the specific magneto-mechanical loading of this problem. In order to decrease the need for bias magnetic field and increase system efficiency, a new return mechanism for the MSMA specimen is proposed. The results indicate that the maximum harvested power from the improved system is obtained at... 

    Effects of Mechanical Loading Environment on Aneurysm

    , M.Sc. Thesis Sharif University of Technology Abdollahi, Rahim (Author) ; Abedian, Ali (Supervisor)
    Abstract
    Human body is subjected to body accelerations or vibrations in several circumstances. During gravitational changes, the hydrostatic pressure gradient along the body axis changes, and then body fluids are redistributed. Prolonged exposure to high level external acceleration may lead to serious or even fatal situations on account of disturbances in blood flow. Due to physiological importance of body acceleration many theoretical investigations have been carried out for the flow of blood under the influence of body acceleration. In this study, the mechanical loads that pilots experience during flight are considered. The aim of the present study is to investigate the effects of mechanical... 

    Stress analysis of thermal barrier coating system subjected to out-of-phase thermo-mechanical loadings considering roughness and porosity effect

    , Article Surface and Coatings Technology ; Volume 262 , January , 2015 , Pages 77-86 ; 02578972 (ISSN) Rezvani Rad, M ; Farrahi, G. H ; Azadi, M ; Ghodrati, M ; Sharif University of Technology
    Elsevier  2015
    Abstract
    This paper presents the out-of-phase thermo-mechanical stress analysis of thermal barrier coating (TBC) system in real working conditions used as thermal barrier in diesel engine cylinder heads. The coating system in this research comprises 350. μm zirconium oxide top coat (TC) and 150. μm metallic bond coat (BC). These layers were deposited on the substrate, aluminum A356 alloy, by the aid of air plasma spray (APS) method. Afterwards, the specimen was subjected to thermo-mechanical fatigue (TMF) loadings. Based on the experimental conditions, FE simulations were performed by both time-independent and time-dependent substrate material properties in ABAQUS software. Simulation results related... 

    Study of the Gating Mechanism of Mechanosensitive Membrane Channels

    , M.Sc. Thesis Sharif University of Technology Rasouli, Ali (Author) ; Nejat Pishkenari, Hoessein (Supervisor) ; Zohour, Hassan (Supervisor) ; Jamali, Yousef (Co-Advisor)
    Abstract
    Mechanosensitive membrane channels are indispensable part of cells that sense and respond to mechanical signals. Hence, malfunction of these channels may cause various diseases. Despite numerous studies of these channels, there are still many unanswered questions surrounding these channels and their gating mechanism. Although there have been valuable experimental studies in this field, the need for modelling and computational studies are still felt since experiments face many limitations in this area. Thus, a channel that its crystallographic structure has been recently determined was chosen and studied using computational tools. In this study, gating of the channel under surface tension has... 

    Dynamic Buckling of Laminated Composite Beams Resting on Elastic Foundation under Thermal and Mechanical Load

    , M.Sc. Thesis Sharif University of Technology Eshrati, Mojtaba (Author) ; Kouchakzadeh, Mohammad Ali (Supervisor)
    Abstract
    In this study, static and dynamic buckling of laminated composite beams resting on an elastic foundation under thermal and mechanical load is studied. Beam is resting on an elastic foundation with hardening/softening term. Nonlinear governing equations are obtained based on the energy method and are solved via the multi-term Galerkin method and the Newton-Raphson numerical method. Critical dynamic load is estimated by the Hoff Simitses criterion. The results are validated with the results of available articles in this field. In the following, the effects of different parameters of the problem on the results are examined. Results reveal that for a sufficiently stiff softening elastic... 

    Modeling of Magnetic Shape Memory Alloys Plates

    , M.Sc. Thesis Sharif University of Technology Naderi, Hossein (Author) ; Sayyaadi, Hassan (Supervisor)
    Abstract
    Magnetic shape memory alloys (MSMAs) are a new class of smart materials which exhibit properties such as large reversible strains and high performance frequencies. These unique properties, offer magnetic shape memory alloys as an option in applications such as actuators, sensors and energy harvesters. In this thesis, the equations of magnetic shape memory alloys by considering nonlinear terms of Von karaman in strain-displacement relations, is expanded by using the theory of thin plates in two dimensions which can be used for plate equations with any boundary conditions by applying elastic boundary. In order to verify the obtained model, the equations of motions of magnetic shape memory... 

    Mixed mode fracture analysis of adiabatic cracks in homogeneous and non-homogeneous materials in the framework of partition of unity and the path-independent interaction integral

    , Article Engineering Fracture Mechanics ; Vol. 131, issue , 2014 , Pp. 100-127 ; ISSN: 00137944 Goli, E ; Bayesteh, H ; Mohammadi, S ; Sharif University of Technology
    Abstract
    In this paper, the path independent interaction integral has been implemented in the framework of the extended finite element method for mixed mode adiabatic cracks under thermo-mechanical loadings particularly in orthotropic non-homogenous materials. The mesh insensitivity and increased accuracy due to the thermal and displacement asymptotic analytical solutions are discussed and the contour independency of the interaction integral is investigated in different examples. Finally, the problem of crack propagation in orthotropic FGM materials under the thermal loading is investigated to assess the accuracy and robustness of proposed approach  

    Nonlinear bending of functionally graded tapered beams subjected to thermal and mechanical loading

    , Article International Journal of Non-Linear Mechanics ; Vol. 65, issue , October , 2014 , p. 141-147 Niknam, H ; Fallah, A ; Aghdam, M. M ; Sharif University of Technology
    Abstract
    Non-linear bending analysis of tapered functionally graded (FG) beam subjected to thermal and mechanical load with general boundary condition is studied. The governing equations are derived and a discussion is made about the possibility of obtaining analytical solution. In the case of no axial force along the beam, a closed form solution is presented for the problem. For the general case with axial force, the Galerkin technique is employed to overcome the shortcoming of the analytical solution. Moreover, the Generalized Differential Quadrature (GDQ) method is also implemented to discretize and solve the governing equations in the general form and validate the results obtained from two other... 

    Thermo-mechanical behavior of functionally graded circular sector plates

    , Article Acta Mechanica ; Volume 226, Issue 1 , January , 2015 , Pages 37-54 ; 00015970 (ISSN) Fallah, F ; Nosier, A ; Sharif University of Technology
    Springer-Verlag Wien  2015
    Abstract
    By reformulating the governing equations of the first-order theory into those describing the interior and edge-zone problems of the plate, closed-form solutions are presented for analysis of functionally graded circular sector plates with vertex angle (Formula presented.) whose radial edges are simply supported and subjected to transverse loading and heat conduction through the plate thickness. Various types of clamped, simply supported, and free-edge boundary supports are considered on the circular edge of the plate. The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction of the constituents. The effects of material... 

    Non-linear thermo-mechanical cylindrical bending of functionally graded plates

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 222, Issue 3 , 2008 , Pages 305-318 ; 09544062 (ISSN) Fallah, F ; Nosier, A ; Sharif University of Technology
    2008
    Abstract
    Based on the first-order non-linear von Karman theory, cylindrical bending of functionally graded (FG) plates subjected to mechanical, thermal, and combined thermo-mechanical loadings are investigated. Analytical solutions are obtained for an FG plate with various clamped and simply-supported boundary conditions. The closed form solutions obtained are very simple to be used in design purposes. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The effects of non-linearity, material property, and boundary conditions on various response quantities are studied and... 

    A three-dimensional constitutive model for magnetic shape memory alloys under magneto-mechanical loadings

    , Article Smart Materials and Structures ; Volume 26, Issue 1 , 2017 ; 09641726 (ISSN) Mousavi, M. R ; Arghavani, J ; Sharif University of Technology
    Institute of Physics Publishing  2017
    Abstract
    This paper presents a three-dimensional phenomenological constitutive model for magnetic shape memory alloys (MSMAs), developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold for variant reorientation is introduced which improves the model accuracy. Preassumed kinetic equations for magnetic domain volume fractions, decoupled equations for magnetization unit vectors and appropriate presentation of the limit function for martensite variant reorientation lead to a simple... 

    Decoupled stability equation for buckling analysis of FG and multilayered cylindrical shells based on the first-order shear deformation theory

    , Article Composites Part B: Engineering ; Volume 154 , 2018 , Pages 225-241 ; 13598368 (ISSN) Fallah, F ; Taati, E ; Asghari, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    Based on the first-order shear deformation and Donnell's shell theory with von Karman non-linearity, one decoupled stability equation for buckling analysis of functionally graded (FG) and multilayered cylindrical shells with transversely isotropic layers subjected to various cases of combined thermo-mechanical loadings is developed. To this end, the equilibrium equations are uncoupled in terms of the transverse deflection, the force function and a new potential function. Using the adjacent equilibrium method, one decoupled stability equation which is an eighth-order differential equation in terms of transverse deflection is obtained and conveniently solved to present analytical expressions... 

    Estimation of spinal loads using a detailed finite element model of the L4-L5 lumbar segment derived by medical imaging kinematics; A feasibility study

    , Article World Congress on Medical Physics and Biomedical Engineering, WC 2018, 3 June 2018 through 8 June 2018 ; Volume 68, Issue 2 , 2018 , Pages 791-795 ; 16800737 (ISSN) Hashemi, M. S ; Arjmand, N ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    Low back pain is the most prevalent orthopedic disorder and the first main cause of poor working functionality in developed as wells as many developing countries. In Absence of noninvasive in vivo measurement approaches, biomechanical models are used to estimate mechanical loads on human joints during physical activities. To estimate joint loads via musculoskeletal models, the calculation of muscle forces are of importance. It is however difficult to estimate muscle forces as the number of muscles, i.e. unknown parameters, is far more than the existing degrees of freedom; the system is highly redundant. Therefore, in this study, instead of muscle forces estimation, their effects (i.e.,... 

    Energy harvesting from plate using magnetic shape memory alloys

    , Article Proceedings of the 6th RSI International Conference on Robotics and Mechatronics, IcRoM 2018, 23 October 2018 through 25 October 2018 ; 2019 , Pages 229-235 ; 9781728101279 (ISBN) Sayyaadi, H ; Naderi, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Ferromagnetic shape memory alloys (FSMA) are new class of smart material and have been investigated for sensor and actuator and energy harvester applications.this paper presents the basis for a novel pressure sensor based on ferromagnetic shape memory alloys. Underlying mechanism for sensing applications is martensitic reorientation accompanied by a chang of magnetization of plate. When this alloy, is exposed in an external magnetic field or stress, has change of magnetization in result.the change in the magnetization of the alloy in accordance with the Faraday induction law, in the wires of the coil leads to the induction voltage. In this paper, a phenomenological constitutive structural... 

    Analysis and modification of a common energy harvesting system using magnetic shape memory alloys

    , Article Journal of Intelligent Material Systems and Structures ; 2020 Sayyaadi, H ; Mehrabi, M ; Hoviattalab, M ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    In this paper, a common energy harvester is investigated which uses a specimen of magnetic shape memory alloy (MSMA). The aim of this study is to improve system performance and to evaluate the magneto-mechanical loading on the MSMA material. Since demagnetization effect is not included in the employed original MSMA model, a method to incorporate this effect is proposed which has a good performance for the specific magneto-mechanical loading of this problem. In order to decrease the need for bias magnetic field and increase system efficiency, a new return mechanism for the MSMA specimen is proposed. The results indicate that the maximum harvested power from the improved system is obtained at... 

    An Investigation on Elastic and Thermo-elastic Behavior of FGM Skew Plates under Mechanical and Thermo-mechanical Loading

    , M.Sc. Thesis Sharif University of Technology Karami, Adel (Author) ; Abedian, Ali (Supervisor)
    Abstract
    In this research it is aimed to have an investigation on the thermo-mechanical analysis of functionally graded skew plates. In order to analyze the behavior of the skew FGM plates, a constant pressure load as a mechanical load is distributed through the plate. Also the thermo-mechanical load is a combination of this mechanical load and a temperature gradient in upper and lower surface applied as in-phase . Various boundary conditions considered in analysis are combination of simply support and clamped edges including CCCS, CCSS, CCCC. The analysis are based on CPT and the Von-Karman theory is used in the solution. The graded materials are distributed through the thickness according to P-FGM... 

    Nonlinear Analysis of FG Rectangular Plates under Mechanical and Thermo-Mechanical Loads using the Extended Kantorovich Method

    , M.Sc. Thesis Sharif University of Technology Moradkhani, Behrooz (Author) ; Nasier, Asghar (Supervisor)
    Abstract
    The purpose of this research is to provide an analytical solution using first order shear deformation theory for nonlinear bending of rectangular FG plate under mechanical and thermal loads with different boundary conditions. To achieve this goal, extended Kantorovich method have been used. This method has a high convergence rate and is more accurate than other approximate methods, such as the Ritz and Galerkin methods, because the partially differential equations are converted to ordinary differential equations. In order to solving nonlinear odes the perturbation method is used. Material of the plate is a mixture of ceramic and metal and is modeled as an isotropic and non-homogeneous... 

    Physical-Phenomenological Constitutive Modeling and Numerical Analysis of Magnetic Shape Memory Alloys

    , M.Sc. Thesis Sharif University of Technology Mousavi, Mohammad Reza (Author) ; Arghavani, Jamal (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Naghdabadi, Reza (Co-Advisor)
    Abstract
    Magnetic shape memory alloys (MSMAs) are a new class of smart materials that exhibit characteristics of large recoverable strains and high frequency. These unique characteristics, make MSMAs interesting materials for applications such as actuators, sensors, and energy harvesters. This thesis presents a three-dimensional phenomenological constitutive model for MSMAs, developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold needed for variant reorientation is introduced which... 

    Strain gradient thermoelasticity of functionally graded cylinders

    , Article Scientia Iranica ; Volume 21, Issue 4 , 2014 , Pages 1415-1423 ; ISSN: 10263098 Sadeghi, H ; Baghani, M ; Naghdabadi, R ; Sharif University of Technology
    Abstract
    In this paper, strain gradient thermo-elasticity formulation for axisymmetric Functionally Graded (FG) thick-walled cylinders is presented. For this purpose, the elastic strain energy density function is considered to be a function of gradient of strain tensor in addition to the strain tensor. The material properties are assumed to vary according to a power law in radial direction. Using the constitutive equations and equation of equilibrium in the cylindrical coordinates, a fourth order non-homogenous governing equation for thermo-elastic analysis of thick-walled FG cylinders subjected to thermal and mechanical loadings is obtained and solved numerically. Results show that the intrinsic... 

    Electroelastic analysis of FG piezoelectric structures under thermo-electro-mechanical loadings

    , Article Mechanics of Advanced Materials and Structures ; Volume 20, Issue 1 , 2013 , Pages 11-27 ; 15376494 (ISSN) Kargarnovin, M. H ; Hashemi, R ; Emami, A. A ; Sharif University of Technology
    2013
    Abstract
    An exact planar solution for the determination of electroelastic responses are presented for functionally graded piezoelectricmaterials (FGPMs). The electro-mechanical properties are assumed to vary exponentially. Exploiting the potential functions for stress and induction, the governing equations reduce to systems of fourth order inhomogeneous partial differential equations (PDEs), which are solved in a closed form manner. Validity of the obtained solution is checked by other existing results in the literatures. Several examples are provided under distinctive thermo-electro-mechanical loadings. Finally, the effect of the graded indices is examined upon the electroelastic response of the FGP...