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Synthesis of Super-porous Nano Structure Nitinol by Milling using Space Holder Technics and Measure of Termomechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
NiTi is known as a most important material for manufacturing implants and other medical devises duo to its shape memory and super elasticity properties, high energy damping and high corrosion resistance.In this project the possibility of producing nano structured NiTi implant with high porosity was investigated. For reaching to nano scale mechanical alloying process was done on Ti and Ni powder as row materials. Mechanical alloying process and the possibility of reaching nano structure or amorphous phase was investigated. Space holder technic was used for reaching a porous structure. Sintering process was planned in a way to inhibit grain growth as much as possible. The samples sintered in...
Recent advances in the applications of shape memory alloys in civil infrastructures: A review
, Article Structures ; Volume 27 , 2020 , Pages 1535-1550 ; 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...
Nitinol spinal vertebrae: A favorable new substitute
, Article International Journal of Engineering, Transactions B: Applications ; Volume 32, Issue 6 , 2019 , Pages 842-851 ; 1728144X (ISSN) ; Parsafar, M ; Rashtiani, Y ; Jadidi, M ; Sharif University of Technology
Materials and Energy Research Center
2019
Abstract
Scoliosis, kyphosis, and bone fracture are health problems, especially of the elderly throughout the world. The vertebra protects the spinal cord. Any impairment to the vertebra can lead to pain and nervousness. NiTi alloy (Nitinol) helps to resolve the problem by fulfilling such requirements as for strength, durability, resistance to wear, and shockwave damping which is due to the shape memory effect. Nitinol medical applications have so far been restricted to surgical devices and orthopaedics. Little has been said about Nitinol use for medication of the spinal vertebra disorder. This article appraises the potential features of Nitinol for vertebral implantation and therapeutic prescription...
Incremental Modeling of Magnetic Shape Memory Alloys
,
M.Sc. Thesis
Sharif University of Technology
;
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...
Investigating The Seismic Performance of R/C Buildings Equipped With Shape Memory Alloy Braces
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Shape memory alloys (SMAs) are metallic materials that have unique properties, including shape memory effects, superelastic effects, and high damping characteristics. Recovery of large deformation and capability of energy dissipation during mechanical loading-unloading cycles are special properties of superelastic effect of shape memory alloys. Due to these distinctive macroscopic behaviors, not present in most traditional materials, SMAs are the basis for innovative applications like devices for protecting buildings from structural vibrations. This paper presents a numerical investigation aimed at evaluating the improvements achievable through devices for passive seismic protection of...
Investigation onthe Seismic Behavior of Steel MRF with Shape Memory Alloy Equipped Connections
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Various types of passive energy dissipating systems have been introduced for controlling the seismic response of structures during the last few decades. A number of these control devices have been practically implemented in different structures all over the world. Shape Memory Alloy (SMA) is among those passive control systems that have attracted a large attention due to its innate features, i.e., recovering the induced residual strains upon unloading (superelastic effect) or by heating (shape memory effect).This study investigates the seismic behavior of a set of steel structural models with different number of stories and eccentricities equipped with a type of fixed SMA connections. In the...
Application of SMA-Equipped Connections in Improving the Seismic Behavior of Steel Structures
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooie, Fayyaz (Supervisor)
Abstract
Application of Shape Memory Alloys (SMAs) as a means for vibration suppression of structural systems has extensively been explored in recent years. Recovering the applied residual strain upon unloading (super-elasticity) or by heating (shape memory effect) at different temperature ranges are two inherent features of SMA materials that have gained most attention. In this work, the seismic behavior of a proposed beam-column semi-rigid end-plate connection that has been equipped with both steel and SMA studs in austenite phase is investigated. A number of 3-D steel MRF structural models with 6,9 and 12 number of stories are considered. These structural models are subjected to bi-directional...
Analysis and Simulation of Shape Memory Alloy Wire Rope Isolator
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Arghavani Hadi, Jamal (Supervisor)
Abstract
Abstract Wire rope isolators are certain types of isolators that due to simplicity of structure and low maintenance costs are taken into consideration in various industries.A variety of different geometries and different features are provided so far that each have their own advantages and disadvantages. The main point is that in all cases they have large-scales. Therefore the usage of them in micro applications is not practical.Shape memory alloys are a class of materials with specific properties such as superelasticity and have inherent hysteresis. It is expected to achieve smaller dimensions suitable for use in micro-applications if they are used in the manufacturing of wire rope...
Thermo-Mechanical Behavior of Shape Memory Alloys Under Multiaxial Loadings: Constitutive Modeling and Numerical Implementation at Small and Finite Strains
, Ph.D. Dissertation Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
Abstract
Shape memory alloys (SMAs) are a type of smart materials which have unique features known as pseudo-elasticity, one-way and two-way shape memory eects. The interest in the mechanical behavior of SMAs is rapidly growing with the increasing number of potential industrial applications. The origin of SMA material features is a reversible thermo-elastic martensitic phase transformation between a high symmetry, austenitic phase and a low symmetry, martensitic phase. In most applications, SMAs experience general non-proportional thermo-mechanical loads. Thus, according to experimental observations, the so-called variant reorientation should be considered in the constitutive model development....
Design and Fabrication of Thermoelastic Nitinol Implant with Radius Variation for Denture Base Replacement
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
In this research to solve the problems related to titanium implants, a new type of dental implant was designed and fabricated by using shape memory and pseudoelasticity properties of porous nitinol alloys. The elastic modulus of this implant (equal to 0.8 GPa) is similar to the cancellous jaw bone (equal to 0.3-1 GPa) which causes a normal distribution of stress and prevents bone resorption. The current approach is use of radius variation to facilitate implant surgery. These radial changes are created by using one way shape memory effect. First, the implant enters the jaw cavity by decreasing the radius and after reaching the body temperature and restoring the initial shape, the radius 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) ; 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...
Investigation on the seismic behavior of steel MRF with shape memory alloy equipped connections
, Article Procedia Engineering ; Volume 14 , 2011 , Pages 3325-3330 ; 18777058 (ISSN) ; Farhidzadeh, A ; Sharif University of Technology
2011
Abstract
Shape Memory Alloys (SMA) are among the new passive control devices that have gained a large attention due to its inherent features, i.e., recovering the induced residual strains upon unloading (superelastic effect) or by heating (shape memory effect). In this work, the seismic behavior of a set of steel structural models with different number of stories and eccentricities equipped with a type of fixed SMA connections is investigated. Considering an existing SMA connection model in austenite phase, the related moment-rotation behavior is verified through numerical simulation. Then, extensive nonlinear dynamic analyses are performed using a number of 3, 6, 9, and 12 story structural models...
Porous shape memory dental implant by reactive sintering of TiH2–Ni-Urea mixture
, Article Materials Science and Engineering C ; Volume 107 , 2020 ; Sadrnezhaad, S .K ; Hosseini, S. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
We produced bifurcated bone-like shape memory implant (BL-SMI) with desirable tooth-root fixation capability by compact-sintering of TiH2–Ni-urea mixture. The primary constituents of the porous product were Ni and Ti. We could adjust the pores' shape, size, and interconnectivity for favorite bone ingrowth by using urea as a space holder. Without urea, we obtained an average porosity of 0.30, and a mean void size of 100 μm. With 70 vol % urea, we got 62% interconnected pores of 400 μm average size. Aging allowed us to tune the austenite-martensite transformation temperatures towards the needed body tissue arouse. Differential scanning calorimetry measured the transformation temperatures....
Numerical study of an innovative SMA based beam-column connection in reducing the seismic response of steel MRF structures
, Article Scientia Iranica ; Volume 23, Issue 5 , 2016 , Pages 2033-2043 ; 10263098 (ISSN) ; Yadegari Farzaneh, A ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
During recent years, Shape Memory Alloys (SMAs) have been effectively used to control the seismic response of structural systems. Recovering the residual strains upon unloading (super-elasticity) or by heating (shape memory effect) is the main characteristic of SMA materials. This paper explores the efficiency of a proposed application of steel & SMA bolts in improving the seismic behavior of connections in steel Moment Resisting Frame (MRF) structures. A new semi-rigid, end-plate, beam-column connection is introduced, which is based on parallel application of steel and austenite-phase SMA bolts. A number of 3-D steel MRF structural models with different numbers of stories and mass...
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) ; 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...