scholarly journals Behaviour of NiTi SMA Helical Springs under Different Temperatures and Deflections

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
R. Santhanam ◽  
Y. Krishna ◽  
M. S. Sivakumar
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Shape Recovery ◽  
Scanning Calorimetry ◽  
Helical Springs ◽  
Heating And Cooling ◽  
Niti Sma ◽  
Different Temperatures ◽  
Sma Spring ◽  
Sma Helical Spring

Shape memory alloys (SMAs) are one of the most widely used smart materials in many applications because of their shape memory effect property. In this work, the behaviour of NiTi SMA helical spring was evaluated through isothermal force-displacement experiment (IFDE) and shape recovery force experiment (SRFE). The transformation temperatures of SMA spring were determined by differential scanning calorimetry (DSC) test. In situ heating of SMA spring by direct electric current was used instead of conventional furnace heating. The continuous measurement of temperature of SMA spring during heating and cooling was ensured with attaching the thermocouple by heat shrinkable sleeve. From IFDE, the force-deflection behaviour under different constant temperatures and from SRFE and the force-temperature behaviour under different constant deflections are obtained. The results of IFDE show that the force increases and the residual displacement decreases with an increase in the temperature, and the stiffness of the spring at austenite state is greater than that at martensitic state. The results of SRFE show that the shape recovery force increases more or less linearly with an increase in the initial deflection for the same temperature range. But the shape recovery forces are not similar during heating and cooling stages. This paper presents the experimental setup, experimental procedures, and the observed behaviour of SMA helical springs under different temperatures and deflections.

scholarly journals A New Approach to the Design of Helical Shape Memory Alloy Spring Actuators

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Esuff Khan ◽  
Sivakumar M. Srinivasan
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Design Procedure ◽  
Transformation Strain ◽  
Design Approach ◽  
Temperature Phase ◽  
Helical Springs ◽  
Traditional Design ◽  
Residual Deformations ◽  
Sma Spring

Shape memory alloys (SMAs) are smart materials that have the ability to recover their original shape by eliminating residual deformations, when subjected to adequate temperature rise (Shape memory effect). This special behavior attracts the use of SMAs as efficient stroke/force actuators. Most of the engineering applications require helical springs as actuators and proper design of SMA helical spring actuators is very important. In the traditional design approach of SMA spring (Waram, 1993), only strain between linear zones was considered in order to simplify the design and to improve the fatigue life. Only modulus difference between high-temperature and low-temperature phase was utilized, and the transformation strain was not considered as the total transformation strain will be more and will degrade the performance of actuator. In the present design, we have shown that transformation strain can be restricted by using hard stops and the partial transformation strain can be used to improving the capacity of SMA spring actuator. A comparison of the traditional design approach of SMA spring and the proposed design procedure has been made to give an idea of its effect on the design and the related parameters.

Experimental Validation and Numerical Simulation of Shape Memory Flat Wire Actuators

2014 ◽  
Author(s):  
Alexander Czechowicz ◽  
Sven Langbein
Keyword(s):  
Shape Memory Alloy ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Smart Materials ◽  
Empirical Data ◽  
Dynamic Properties ◽  
Fatigue Behavior ◽  
Different Boundary Conditions ◽  
Heating And Cooling ◽  
Actual Shape

Shape memory alloys (SMA) are thermally activated smart materials. Due to their ability to change into a previously imprinted actual shape through the means of thermal activation, they are suitable as actuators for mechatronical systems. Despite of the advantages shape memory alloy actuators provide, these elements are only seldom integrated by engineers into mechatronical systems. Reasons are the complex characteristics, especially at different boundary conditions and the missing simulation- and design tools. Also the lack of knowledge and empirical data are a reason why development projects with shape memory actuators often lead to failures. This paper deals with the dynamic properties of SMA-actuators (Shape Memory Alloy) — characterized by their rate of heating and cooling procedures — that today can only be described insufficiently for different boundary conditions. Based on an analysis of energy fluxes into and out of the actuator, a numerical model of flat-wire used in a bow-like structure, implemented in MATLAB/SIMULINK, is presented. Different actuation parameters, depending on the actuator-geometry and temperature are considered in the simulation in real time. Additionally this publication sums up the needed empirical data (e.g. fatigue behavior) in order to validate the numerical two dimensional model and presents empirical data on SMA flat wire material.

Nickel–titanium shape memory alloy mechanical components produced by investment casting

2018 ◽  
Vol 29 (19) ◽  
pp. 3748-3757 ◽  
Author(s):  
Jackson de Brito Simões ◽  
Carlos José de Araújo
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Investment Casting ◽  
Mechanical Characterization ◽  
Nickel Titanium ◽  
Compression Tests ◽  
Thermoelastic Martensitic Transformation ◽  
Scanning Calorimetry ◽  
Helical Springs ◽  
Mechanical Components

This work aimed to produce mechanical components of nickel–titanium shape memory alloys using investment casting processes. Then, in order to validate processing, different designs of nickel–titanium shape memory alloy components as staple implants, Belleville springs, meshes, helical springs, screws and hexagonal honeycombs were produced and submitted to thermal and mechanical characterization. Thermoelastic martensitic transformation of the nickel–titanium shape memory alloy parts was determined by differential scanning calorimetry and electrical resistance with temperature, while the superelastic behaviour was verified by cyclic tensile and compression tests. It has been demonstrated that the employed investment casting processes are suitable to manufacture nickel–titanium shape memory alloy mechanical components with simple and complicated designs as well as functional properties related to phase transformation and superelasticity.

scholarly journals Bio-Based Epoxy Shape-Memory Thermosets from Triglycidyl Phloroglucinol

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 542 ◽  
Author(s):  
David Santiago ◽  
Dailyn Guzmán ◽  
Francesc Ferrando ◽  
Àngels Serra ◽  
Silvia De la Flor
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Memory Performance ◽  
Crosslinking Agent ◽  
Shape Memory Polymers ◽  
Crosslinking Density ◽  
Mechanical Analysis ◽  
Diglycidyl Ether ◽  
Partial Substitution ◽  
Scanning Calorimetry

A series of bio-based epoxy shape-memory thermosetting polymers were synthesized starting from a triglycidyl phloroglucinol (3EPOPh) and trimethylolpropane triglycidyl ether (TPTE) as epoxy monomers and a polyetheramine (JEF) as crosslinking agent. The evolution of the curing process was studied by differential scanning calorimetry (DSC) and the materials obtained were characterized by means of DSC, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), stress-strain tests, and microindentation. Shape-memory properties were evaluated under free and totally constrained conditions. All results were compared with an industrial epoxy thermoset prepared from standard diglycidyl ether of Bisphenol A (DGEBA). Results revealed that materials prepared from 3EPOPh were more reactive and showed a tighter network with higher crosslinking density and glass transition temperatures than the prepared from DGEBA. The partial substitution of 3EPOPh by TPTE as epoxy comonomer caused an increase in the molecular mobility of the materials but without worsening the thermal stability. The shape-memory polymers (SMPs) prepared from 3EPOPh showed good mechanical properties as well as an excellent shape-memory performance. They showed almost complete shape-recovery and shape-fixation, fast shape-recovery rates, and recovery stress up to 7 MPa. The results obtained in this study allow us to conclude that the triglycidyl phloroglucinol derivative of eugenol is a safe and environmentally friendly alternative to DGEBA for preparing thermosetting shape-memory polymers.

In situ Transmission Electron Microscopy and Nanoindentation Studies of Phase Transformation and Pseudoelasticity of Shape-memory Titanium-nickel Films

2005 ◽  
Vol 20 (7) ◽  
pp. 1808-1813 ◽  
Author(s):  
X.-G. Ma ◽  
K. Komvopoulos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Transformation ◽  
Shape Memory ◽  
Heating And Cooling ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Titanium Nickel ◽  
In Situ Heating

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

Thermo-Mechanical Behavior of Epoxy Shape Memory Polymer

2013 ◽  
Vol 721 ◽  
pp. 169-172 ◽  
Author(s):  
Yu Gu ◽  
Shao Xiong Li
Keyword(s):  
Mechanical Behavior ◽  
Shape Memory ◽  
Significant Influence ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Testing Temperature ◽  
Curing Agent ◽  
Different Temperatures ◽  
Viscoelastic Behaviors

The viscoelastic behaviors of shape memory polymers have a significant influence on the function realization of this kind of smart materials. In this study, stress-strain hysteresis under uniaxial tension of epoxy shape memory polymers with varied curing agent contents and types were tested at different temperatures. The effects of the testing temperature, curing-agent type and content on the viscoelastic behaviors of the materials were discussed.

Study of a Cu-Al-Mn Shape Memory Alloy Produced by Plasma Melting Followed by Injection Molding

2014 ◽  
Vol 1611 ◽  
pp. 25-30
Author(s):  
Francisco Fernando Roberto Pereira ◽  
Maria Goretti Ferreira Coutinho ◽  
Bruno Moura Miranda ◽  
Carlos José de Araújo
Keyword(s):  
Injection Molding ◽  
Shape Memory ◽  
Shape Recovery ◽  
Permanent Deformation ◽  
Melting Process ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Dynamical Mechanical Analysis ◽  
Plasma Melting ◽  
New Applications

ABSTRACTShape Memory Alloys (SMA) are characterized by the capacity to recover a permanent deformation after being heated above a critical temperature called Final Austenite Temperature (Af). The Ni-Ti SMA are the most commercially used, however recent studies showed that the Cu-Al-Mn SMA present significant shape recovery and mechanical properties, showing a strong potential for developing new applications. In this context, the main goal of this work is to manufacture a Cu-Al-Mn SMA through a plasma melting process followed by injection molding of liquid metal and then characterize the samples, using the following techniques: Optical Microscopy (OM), Differential Scanning Calorimetry (DSC), Electrical Resistance as a function of Temperature (ERT) tests, Dynamical Mechanical Analysis (DMA) and Microhardness (MH).

scholarly journals OPTIMIZATION OF NICKEL CONTENT ON SOME PROPERTIES OF (NITI) SHAPE MEMORY ALLOY

2020 ◽  
Vol 1 (01) ◽  
pp. 40-47
Author(s):  
Aissa Bouaissi ◽  
Nabaa S Radhi ◽  
Karrar F. Morad ◽  
Mohammad H. Hafiz ◽  
Alaa Abdulhasan Atiyah
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Smart Materials ◽  
Shape Recovery ◽  
Fatigue Behavior ◽  
Nickel Content ◽  
Functionally Graded ◽  
Niti Shape Memory Alloy ◽  
Shape Effect ◽  
The Impact

Shape Memory Alloys (SMAs) are one of the most hopeful smart materials, especially, Nickel–Titanium (NiTi or Nitinol). These alloys are great and desirable due to their excellent reliability and behavior among all the commercially available alloys. In addition, strain recovery, (Ni–Ti) is granulated for a wide variety of medical uses because of its favorite properties such as fatigue behavior, corrosion resistance and biocompatibility. This paper explores the creation and the characterization of functionally graded (NiTi) materials. This work demonstrations the impact of Nickel contains changes on the characteristics of NiTi shape memory alloy, in order to obtain the suitable addition of Nickel contain, which gives the optimal balance between hardness, start and finish martensitic point, shape recovery and shape effect of alloys properties. These materials are prepared to obtain suddenly or gradually microstructure or composition differences inside the structure of one piece of material, the specimens made by powder metallurgy process and the influence of every layer of composite by; micro-hardness, transformation temperature DSC and shape effect. The hardness value and shape recovery decrease with increase nickel content. superior shape memory effect (SME) and shape recovery (SR) properties (i.e., 8.747, 10.270 for SMA-FGM1 SMA-FGM2 respectively, and SR is 1.735, 2.977 for SMA-FGM1 SMA-FGM2) respectively.  

scholarly journals Block Copolymers of Poly(ω-Pentadecalactone) in Segmented Polyurethanes: Novel Biodegradable Shape Memory Polyurethanes

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1928
Author(s):  
Katalin Czifrák ◽  
Csilla Lakatos ◽  
Marcell Árpád Kordován ◽  
Lajos Nagy ◽  
Lajos Daróczi ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Mechanical Analysis ◽  
Attenuated Total Reflectance ◽  
Dibutyltin Dilaurate ◽  
Scanning Calorimetry ◽  
Dynamical Mechanical Analysis ◽  
Good Shape ◽  
Segmented Polyurethanes ◽  
Shape Fixity

In this report, the synthesis of poly(ω-pentadecalactone) (PPDL) (co)polymers and their incorporation into polyurethanes (PUs) are reported. Optimal conditions for the ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) using dibutyltin dilaurate catalyst were established. For the synthesis of linear and crosslinked PUs, 50 kDa poly(ε-caprolactone) (PCL) and 1,6-hexamethylenediisocyanate (HDI) were used. The obtained polyurethanes were characterized by Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (AT-FTIR), differential scanning calorimetry (DSC), and dynamical mechanical analysis (DMA). The DMA of the selected sample showed a rubbery plateau on the storage modulus versus temperature curve predicting shape memory behavior. Indeed, good shape memory performances were obtained with shape fixity (Rf) and shape recovery (Rr) ratios.

Design and characterization of 3D multilayer woven reinforcements shape memory polymer composites

2020 ◽  
pp. 002199832095817
Author(s):  
Ibrahim Goda ◽  
Zakariya Zubair ◽  
Gildas L’Hostis ◽  
Jean-Yves Drean
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Shape Recovery ◽  
Mechanical Performance ◽  
Shape Memory Polymer ◽  
Woven Fabric ◽  
Deformation Analysis ◽  
Shape Memory Behavior ◽  
Functional Composites ◽  
Memory Cycle

Shape memory polymer (SMP) composites are attractive and excellent smart materials due to their outstanding properties and rich functionality as they combine typical mechanical and functional properties of composites with shape memory properties. In particular, 3D reinforced preforms have tremendous potential for the development of functional composites by using the capabilities of 3D woven fabric preform design, and polymer shape memory behavior. Within that scope, this work aims to investigate the shape memory behavior and shape recovery properties of a specific type of 3D multilayer woven SMP composite in response to external stimuli. For this purpose, nine different multilayer stitched fabrics are produced with different weave structures, and different fabric thread densities using polyimide filaments. Then, a series of tests is carried out on these fabrics to evaluate their mechanical and physical properties. The layered fabric design that delivers high mechanical performance is next involved to manufacture the SMP composite samples, for which shape recovery capability is investigated. Fold-deploy and other shape memory cycle tests are performed to evaluate the shape memory characteristics. An optical 3D scanner based on fringe projection is further proposed to precisely acquire the geometry data and perform deformation analysis to quantitatively evaluate the shape fixity and shape recovery behaviors. The results from this study are very promising, demonstrating that these multilayer SMP structures can successfully be recovered following the desired design constraints without noticeable damage.

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