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    Dynamic modeling of a new varying stress SMA actuator for precise applications

    , Article Proceedings of the IEEE International Conference on Mechatronics 2004, ICM'04, Istanbul, 3 June 2004 through 5 June 2004 ; 2004 , Pages 209-214 ; 0780385993 (ISBN) Alasty, A ; Shameli, E ; Sharif University of Technology
    2004
    Abstract
    Shape Memory Alloys (SMA's) are inherently non-linear devices exhibiting significant hysteresis in their stress-strain-temperature characteristic. We have used the variable sub-layer SMA model of Ikuta [3] to extract the advanced dynamic model of our proposed varying stress SMA actuator. A nonlinear finite element analysis was used to model the proposed bending spring in the actuator and the extended variable sub-layer model of Ikuta was considered to extract stress-displacement relations. Finally, these two models are combined with thermo dynamic model of SMA and a schematic flowchart is proposed to calculate SMA resultant strain under an arbitrary current input. At the end, we applied this... 

    Shape memory alloy in tension and compression and its application as clamping-force actuator in a bolted joint: Part 1 - Experimentation

    , Article Journal of Intelligent Material Systems and Structures ; Volume 15, Issue 8 , 2004 , Pages 577-587 ; 1045389X (ISSN) Hesse, T ; Ghorashi, M ; Inman, D. J ; Sharif University of Technology
    2004
    Abstract
    In recent years, there have been some endeavors in order to characterize and model Shape Memory Alloy (SMA) behavior both in tension and compression. However, the one-dimensional behavior of SMA has been mostly studied for the case of wire elements subjected to tension. The objective of this paper is to analyze the behavior of Ni-55.7% wt Ti SMA in tension, compression, and at various temperatures. The effects of cycling, annealing, and friction on the mechanical behavior of this material in compression are discussed as well and, where applicable, compared to those of tension. The compressed SMA rings are finally used as clamping-force actuators in loosed bolted joints. In the second part of... 

    Mechanical response of single and double-helix SMA wire ropes

    , Article Mechanics of Advanced Materials and Structures ; Volume 29, Issue 26 , 2022 , Pages 5393-5406 ; 15376494 (ISSN) Vahidi, S ; Arghavani, J ; Choi, E ; Ostadrahimi, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    In this paper, based on three-dimensional phenomenological model and using a user-defined material subroutine mechanical behavior of shape memory alloy (SMA) wire ropes (or cables) and their components have been studied through implicit solution method in Abaqus software. Material parameters have been extracted using available experimental data and numerical simulations. Due to the convoluted geometry and interwire contact status within a cable, a finite element analysis is firstly performed for a 1 × 37 steel wire rope to validate modeling and mechanical interactions of a wire rope. Afterwards, superelastic and shape memory effect cables with different constructions (7 × 7 and 1 × 27) are... 

    Study of behavior of reinforced concrete beams with smart rebars using finite element modeling

    , Article International Journal of Civil Engineering ; Volume 8, Issue 3 , September , 2010 , Pages 221-231 ; 17350522 (ISSN) Khaloo, A. R ; Eshghi, I ; Piran Aghl, P ; Sharif University of Technology
    2010
    Abstract
    In this paper the response of cantilevered reinforced concrete (RC) beams with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is SuperelasticShape Memory Alloys (SE SMAs) which contains nickel and titanium elements. The SE SMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this study, different quantities of steel and smart rebars have been used for reinforcement andthe behavior of these models under lateral loading, including their load-displacement curves, residual displacements, and stiffness, were discussed. During... 

    Recent advances in the applications of shape memory alloys in civil infrastructures: A review

    , Article Structures ; Volume 27 , 2020 , Pages 1535-1550 Zareie, S ; Issa, A. S ; Seethaler, R. J ; Zabihollah, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Shape Memory Alloys (SMAs) are a new generation of smart materials with the capability of recovering their predefined shape after experiencing a large strain. This is mainly due to the shape memory effects and the superelasticity of SMA. These properties make SMA an excellent alternative to be used in passive, semi-active, and active control systems in civil engineering applications. This paper presents a comprehensive review of the recent developments in the applications of SMA in civil infrastructures, including, steel, concrete, and timber structures. This review reveals the significance of SMA in civil infrastructures particularly, the enhancement of structural behavior and energy... 

    Shape memory alloy in tension and compression and its application as clamping force actuator in a bolted joint: Part 2 - Modeling

    , Article Journal of Intelligent Material Systems and Structures ; Volume 15, Issue 8 , 2004 , Pages 589-600 ; 1045389X (ISSN) Ghorashi, M ; Inman, D. J ; Sharif University of Technology
    2004
    Abstract
    The mathematical modeling of a bolted joint with a Shape Memory Alloy (SMA) actuator ring is presented. In this way, phase transformation, constitutive and displacement compatibility equations are used. The obtained model is utilized to show how the application of the SMA actuator ring in the bolted joint can help the joint to recover a significant amount of its lost clamping force. The model is run using the experimental data obtained for the Ni-55.7%wt Ti SMA in the companion paper (Part 1). The mechanical properties of SMA are calculated using the mentioned equations and compared to the experimental findings. It is observed that the final clamping force obtained theoretically is close to... 

    Effects of VIM frequency on chemical composition, homogeneity and microstructure of NiTi shape memory alloy

    , Article Materials Science and Technology ; Volume 20, Issue 5 , 2004 , Pages 593-598 ; 02670836 (ISSN) Badakhshan Raz, S ; Sadrnezhaad, S. K ; Sharif University of Technology
    2004
    Abstract
    The concentration distribution and microstructure of NiTi shape memory alloys produced in vacuum induction furnaces operating at high and medium frequencies are compared with those of materials melted in vacuum resistance furnaces. The production procedure consisted of charging pure metals into a graphite crucible; raising the temperature to 1450°C under vacuum; holding the materials in high and medium frequency induction and resistance furnaces for 3, 5, and 120 min under vacuum; and allowing alloys to solidify in the crucibles under the same vacuum. The procedures in each of the three furnaces were made as similar as possible. Chemical composition, microstructure, and surface hardness of... 

    An improved, fully symmetric, finite-strain phenomenological constitutive model for shape memory alloys

    , Article Finite Elements in Analysis and Design ; Volume 47, Issue 2 , 2011 , Pages 166-174 ; 0168874X (ISSN) Arghavani, J ; Auricchio, F ; Naghdabadi, R ; Reali, A ; Sharif University of Technology
    2011
    Abstract
    The ever increasing number of shape memory alloy applications has motivated the development of appropriate constitutive models taking into account large rotations and moderate or finite strains. Up to now proposed finite-strain constitutive models usually contain an asymmetric tensor in the definition of the limit (yield) function. To this end, in the present work, we propose an improved alternative constitutive model in which all quantities are symmetric. To conserve the volume during inelastic deformation, an exponential mapping is used to arrive at the time-discrete form of the evolution equation. Such a symmetric model simplifies the constitutive relations and as a result of less... 

    Study of microstructural growth under cyclic martensite phase transition in shape memory alloys; A molecular dynamics approach

    , Article Journal of Intelligent Material Systems and Structures ; Volume 33, Issue 4 , 2022 , Pages 604-616 ; 1045389X (ISSN) Moravej, S. A ; Taghibakhshi, A ; Nejat Pishkenari, H ; Arghavani, J ; Sharif University of Technology
    SAGE Publications Ltd  2022
    Abstract
    Shape memory alloys are referred to as a group of alloys that can retrieve the permanent deformation and strain applied to them and eventually return to their original form. So far, various studies have been done to determine the behavior of these alloys under cyclic loading. Most of the studies have mainly been conducted by using the foundations of Continuum Mechanics in order to examine the properties of memory alloys. In this study, instead of using the Continuum Mechanics, a Molecular Dynamics simulation method using Lennard-Jones potential is utilized. The changes in the behavior and properties of memory alloy under cyclic loading are being examined. First, the functional form... 

    An Investigation on Concrete Frames Reinforced with Shape Memory Alloys in Plastic Hinge Zones

    , M.Sc. Thesis Sharif University of Technology Mobini, Mohammad Hossein (Author) ; Khalu, Alireza (Supervisor)
    Abstract
    In this paper, the response of a concrete one-story frame with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is Shape Memory Alloy (SMA) which contains nickel and titanium elements. During lateral loading, rebars yield or concrete crushes in compression zone in some parts of the RC frames and also residual deflections are created in the structure. The SMA exhibits little residual strains under cycles of loading and unloading even after passing the yielding zone. In addition, SMAs have a good energy dissipation capacity that helps reduce damage while increasing structural capacity. In this study, SMA rebars... 

    Evaluation of Porous NTI SMA Formation Mechanism, Pore Characteristics and Thermo-Mechanical Properties Produced by Power Metallurgy for Biomedical Application

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Abbas (Author) ; Sadrnezhad, Khatiboleslam (Supervisor)
    Abstract
    Porous NiTi specimens were produced by elemental nickel and titanium powders and two different temporary space-holder consisting of NaCl and urea and conventional sintering method. Pore characteristic and morphology of porous NiTi specimens was investigated by optical and electron microscopy. Microstructure of specimens was probed using XRD and SEM. Suitable pore distribution and size for biomedical application was obtained using temporary space-holder method. Porosity content increases with increasing space holder powder. At 70 volume percent space-holder, best pore size and distribution with fully open pores, in size 200-500 µm, was obtained and pores are interconnected that suitable for... 

    Vibration Control of Micro-Satellite Shelves Using Shpae Memory Alloy

    , M.Sc. Thesis Sharif University of Technology Hedayati Dezfuli, Farshad (Author) ; Abedian, Ali (Supervisor)
    Abstract
    Dynamic properties such as the natural frequency of a structure have a significant role in the design process. The importance of this consideration is because of resonance. In this case, the amplitude of the vibration is magnified to levels that may lead to a catastrophic event. While the usual design process depends on the collected experiences and statistical data, a developing trend is to implement smart technologies to develop smart structures that are capable of self-monitoring, diagnostics and repair. Smart material components such as shape memory alloys (SMAs) and piezoelectric ceramics are increasingly being used by vibration control practitioners. Shape memory alloys are applied as... 

    A novel inertial energy harvester using magnetic shape memory alloy

    , Article Smart Materials and Structures ; Volume 25, Issue 10 , 2016 ; 09641726 (ISSN) Askari Farsangi, M. A ; Sayyaadi, H ; Zakerzadeh, M. R ; Sharif University of Technology
    Institute of Physics Publishing  2016
    Abstract
    This paper studies the output voltage from a novel inertial energy harvester using magnetic shape memory alloys (MSMAs). The MSMA elements are attached to the root of a cantilever beam by means of two steps. In order to get electrical voltage, two coils are wound around the MSMAs and a shock load is applied to a tip mass at the end of the beam to have vibration in it. The beam vibration causes strain in the MSMAs along their longitudinal directions and as a result the magnetic flux alters in the coils. The change of magnetic flux in the surrounding coil produces an AC voltage. In order to predict the output voltage, the nonlinear governing equations of beam motion based on Euler-Bernoulli... 

    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... 

    Multiphysics modeling of an MSMA-based clamped-clamped inertial energy harvester

    , Article Smart Materials and Structures ; Volume 28, Issue 3 , 2019 ; 09641726 (ISSN) Askari Farsangi, M. A ; Zakerzadeh, M. R ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    In this paper, an alternative way of harvesting energy from ambient vibration is investigated through proposing a novel inertial energy harvester using magnetic shape memory alloys (MSMAs). To this end, a clamped-clamped beam is coupled with MSMA units which are attached to its roots. A shock load is applied to a proof mass in the middle of the beam. The beam vibration causes longitudinal strain in the MSMAs and as a result the magnetic flux alters in the coils wounding around the MSMA units and produce an AC voltage. To have a reversible strain in MSMAs, a bias magnetic field is applied in transverse direction of the MSMA units. The large scale vibration of Euler-Bernoulli beam is modeled... 

    A novel shape memory alloy-based element for structural stability control in offshore structures under cyclic loading

    , Article Ships and Offshore Structures ; Volume 15, Issue 8 , 2020 , Pages 844-851 Zareie, S ; Alam, M. S ; Seethaler, R. J ; Zabihollah, A ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    Wind and ocean waves highly influence the performance and functionality of structures, requiring an efficient control element. The structural behavior of one of the most recent structural control elements, namely shape memory alloys (SMA)-based control element, under cyclic loadings of oceans waves, has been investigated. Shape memory alloys are one of the attractive smart materials with the ability to return to the initial shape after experiencing large deformation. Experimental tests have been conducted to study the effects of cyclic loads on several specimens of the SMA wires. The SMA wires are being used in the SMA-based structural control system to dissipate the energy of external... 

    A study of pre-straining shape memory alloy (SMA)-based control elements subject to large-amplitude cyclic loads

    , Article Ships and Offshore Structures ; 2020 Zareie, S ; Zabihollah, A ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    Dynamic environmental loads, such as winds and waves, make the stability of offshore structures at high risk, requiring reliable yet efficient control elements to ensure the stability of such structures under lateral loads. Among the variety of control elements that have been developed to enhance the stability of a structure, shape memory alloy (SMA)-based control elements are promising as they are low-cost, easy to embed into the main control element, and do not need an external power supply. However, cyclic loads may highly influence the performance and functionality of SMA-based elements. The present work investigates the effects of pre-straining SMA components in energy dissipation... 

    Stability control of a novel frame integrated with an SMA-MRF control system for marine structural applications based on the frequency analysis

    , Article Applied Ocean Research ; Volume 97 , 2020 Zareie, S ; Alam, M. S ; Seethaler, R. J ; Zabihollah, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Structural integrity and ensuring the stability of steel frame structures, including marine and coastal structures, are the main challenges for designers in civil infrastructures, particularly in oil platforms, subjected to tough periodic and non-periodic environmental loading conditions. Variable loadings with different amplitudes and frequencies may lead to the stability of steel structures loss. In order to keep the stability of the steel structures and prevent possible damages, reliable yet efficient structural control systems are in demand. Conventional structural control systems need significant activation energy and/or in-depth users knowledge to be effective. Most recently, smart... 

    Incremental Modeling of Magnetic Shape Memory Alloys

    , M.Sc. Thesis Sharif University of Technology Khajehsaeid, Hesam (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    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 posses 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 thesis, MSMAs are modeled by means of incremental modelling which is a useful method in analysis of nonlinear behaviour of materials. Furthermore, stress-strain curve of MSMA is approximated using an analytical expression whose parameters can simply be... 

    Designing a Total Knee Replacement to Obtain Minimum Wear on Contact Surfaces and Reduce the Risk of Loosening Using Fgm and Sma

    , M.Sc. Thesis Sharif University of Technology Naghibi Beidokhti, Hamid (Author) ; Ahmadiyan, Mohammad Taghi (Supervisor) ; Zohoor, Hassan (Co-Advisor)
    Abstract
    In recent years, Total Knee Replacement is a highly common surgery. Other than the injuries caused by trauma in accidents among different ages, a need for Total Knee Replacement can arise due to diseases such as Knee Osteoporosis among the elderly which leads to loss of balance in the physiologic properties of knee joint and a failure in load transfer from distal femur to proximal tibia. Currently, the practice of Total Knee Replacement is performed by implanting a mechanical knee between femoral and tibial shafts. Increase in life expectancy of the people with replaced knee, causes the failure of some prostheses due to various factors. Following the failure, a second operation is required...