scholarly journals Mechanical Consequences of Dynamically Loaded NiTi Wires under Typical Actuator Conditions in Rehabilitation and Neuroscience

2021 ◽  
Vol 12 (1) ◽  
pp. 4
Author(s):  
Umut D. Çakmak ◽  
Zoltán Major ◽  
Michael Fischlschweiger
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Storage Modulus ◽  
Loss Factor ◽  
Empirical Relation ◽  
Material Behavior ◽  
Chemical Compositions ◽  
Loading Frequency ◽  
Frequency Dependency ◽  
Controlled Conditions

In the field of rehabilitation and neuroscience, shape memory alloys play a crucial role as lightweight actuators. Devices are exploiting the shape memory effect by transforming heat into mechanical work. In rehabilitation applications, dynamic loading of the respective device occurs, which in turn influences the mechanical consequences of the phase transforming alloy. Hence in this work, dynamic thermomechanical material behavior of temperature-triggered phase transforming NiTi shape memory alloy (SMA) wires with different chemical compositions and geometries was experimentally investigated. Storage modulus and mechanical loss factor of NiTi alloys at different temperatures and loading frequencies were analyzed under force-controlled conditions. Counterintuitive storage modulus- and loss factor-dependent trends regarding the loading frequency dependency of the mechanical properties on the materials’ composition and geometry were, hence, obtained. It was revealed that loss factors showed a pronounced loading frequency dependency, whereas the storage modulus was not affected. It was shown that force-controlled conditions led to a lower storage modulus than expected. Furthermore, it turned out that a simple empirical relation could capture the characteristic temperature dependency of the storage modulus, which is an important input relation for modeling the rehabilitation device behavior under different dynamic and temperature loading conditions, taking directly into account the material behavior of the shape memory alloy.

Shape Memory Effect and Hysteresis Behavior of Shape Memory Alloy Metal Rubber

2012 ◽  
Author(s):  
Jie Hong ◽  
Baolong Liu ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Storage Modulus ◽  
Loss Factor ◽  
Treatment Process ◽  
Structural Parameter ◽  
Treatment Procedure ◽  
Metal Rubber ◽  
Alloy Metal

The present work focuses on the shaping craft of shape memory alloy metal rubber (SMAMR) and its temperature dependent mechanical properties. Heat treatment process was conducted to form a stable SMAMR sample beyond the general procedure of metal rubber (MR) in order to resist the shape memory effect (SME). The influence of the heat treatment procedure on the mechanical properties was tested. The quasi-static experimental investigations were carried out to obtain the storage modulus and energy loss factor varying with the structural parameter, strain amplitude, and material temperature. It is found from the experiment results that the SMAMR sample which underwent the heat treatment was able to remember its original moulding shape and recover from the overloading plastic deformation when heated above the phase transition temperature. For comparison, another sample without the heat treatment was heated to the same temperature after the plastic deformation, but the final shape deviated from the original one. It is also confirmed that the heat treatment procedure obviously increased the storage modulus and loss factor of SMAMR. Just like the variety elastic modulus of shape memory alloy (SMA), the storage modulus of SMAMR increased obviously while the material was heated above the phase transformation temperature due to the elastic modulus change of SMA wire. The quasi-static experiments showed a hysteretic property of the stress–strain curve in a certain temperature. But the hysteretic curve was temperature and structural parameter dependent. It is concluded that the heat treatment process is necessary to obtain a stable SMAMR during the phase transformation. The varying storage modulus and superior loss factor performances of SMAMR make itself a kind of attractive functional material which will be available in the active suppression of vibration. For example, it can be fabricated to a rotor bearing with changeable stiffness and damping, which is of practical significance in the active control of synchronous vibration of rotors crossing resonance condition.

scholarly journals Iron-based shape memory alloy strips for strengthening RC members: Material behavior and characterization

2018 ◽  
Vol 173 ◽  
pp. 586-599 ◽  
Author(s):  
Moslem Shahverdi ◽  
Julien Michels ◽  
Christoph Czaderski ◽  
Masoud Motavalli
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Material Behavior ◽  
Iron Based

Experimental Analysis of Smart Structure with Damping Treatment and SMA

1996 ◽  
Vol 459 ◽  
Author(s):  
Q. Chen ◽  
J. Ma ◽  
C. Levy
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Temperature Effects ◽  
Loss Factor ◽  
Alloy Layer ◽  
Smart Structure ◽  
Viscoelastic Layer ◽  
Heat Cycling ◽  
Damping Materials ◽  
System Frequency

ABSTRACTThe experimental results of a flexible cantilever beam with constrained viscoelastic layer and shape memory alloy layer called smart damping treatment (SDT) are presented. The upper side of the beam is bonded with a viscoelastic layer and then covered with a constraining layer. The lower side is bonded with a shape memory alloy layer, which is used as an actuator. The elastic modulus and loss factor of damping materials are functions of the temperature. The temperature effects on system frequency and loss factor due to heat cycling of SMA layer are evaluated here. It is found that temperature plays an important role on system frequency and loss factor, and thus the temperature effects must be included when discussing such an structure.

One-Dimensional Shape Memory Alloy Model Applicable to Any Status of Stress and Temperature

2006 ◽  
Vol 326-328 ◽  
pp. 1475-1478
Author(s):  
Jong Ha Chung ◽  
Jin Seok Heo ◽  
Myoung Sik Won ◽  
Woo Yong Lee ◽  
Jung Ju Lee
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Principal Factor ◽  
Material Behavior ◽  
Transformation Kinetics ◽  
Dimensional Model ◽  
Suggested Model ◽  
One Dimensional ◽  
Dimensional Shape ◽  
Kinetics Of

The transformation kinetics formulation is the principal factor underlying the constitutive model of shape memory alloys. Therefore, the transformation kinetics formulation, which is applicable to any status of stress and temperature, is essential for predicting the material behavior of SMAs. In this work, we show that the transformation kinetics of the Brinson model, which is the most widely used 1-dimensional model, has shortcomings under certain stress and temperature histories. In addition, we propose a modified transformation kinetics model that can be used for any stress or temperature conditions. The martensite transformation kinetics is modified so that the transformation from austenite into temperature-induced martensite, due to the decrement of temperature, is coupled with a transformation from austenite or temperature-induced martensite into stress-induced martensite, due to the increment of the stress. Through this modification, the suggested model can simulate the behavior of shape memory alloy materials under arbitrarily changed circumstances at every stress-temperature region.

scholarly journals Machine Learning Enhanced Dynamic Response Modelling of Superelastic Shape Memory Alloy Wires

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 304
Author(s):  
Niklas Lenzen ◽  
Okyay Altay
Keyword(s):  
Machine Learning ◽  
Shape Memory Alloy ◽  
Strain Rate ◽  
Shape Memory ◽  
Thermodynamic Parameters ◽  
Expert Knowledge ◽  
Material Behavior ◽  
Model Parameters ◽  
Engineering Structures ◽  
Wide Range

Superelastic shape memory alloy (SMA) wires exhibit superb hysteretic energy dissipation and deformation capabilities. Therefore, they are increasingly used for the vibration control of civil engineering structures. The efficient design of SMA-based control devices requires accurate material models. However, the thermodynamically coupled SMA behavior is highly sensitive to strain rate. For an accurate modelling of the material behavior, a wide range of parameters needs to be determined by experiments, where the identification of thermodynamic parameters is particularly challenging due to required technical instruments and expert knowledge. For an efficient identification of thermodynamic parameters, this study proposes a machine-learning-based approach, which was specifically designed considering the dynamic SMA behavior. For this purpose, a feedforward artificial neural network (ANN) architecture was developed. For the generation of training data, a macroscopic constitutive SMA model was adapted considering strain rate effects. After training, the ANN can identify the searched model parameters from cyclic tensile stress–strain tests. The proposed approach is applied on superelastic SMA wires and validated by experiments.

Smart Damping Treatment for Flexible Structure

1994 ◽  
Vol 360 ◽  
Author(s):  
Q. Chen ◽  
C. Levy
Keyword(s):  
Differential Equation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loss Factor ◽  
Alloy Layer ◽  
Viscoelastic Layer ◽  
Flexible Structure ◽  
Recovery Stress ◽  
Governing Differential Equation ◽  
The Mathematical Model

AbstractThe mathematical model of a flexible cantilever beam with a constrained viscoelastic layer and shape memory alloy layer called smart damping treatment (SDT) is presented. It is shown that a change of the elastic modulus of the shape memory alloy layer will affect the system loss factor and resonance frequency. The recovery stress of the SMA layer leads to an inhomogeneity in the governing differential equation. The recovery stress also functions as an excitation to the system. The effects of the different parameters found in the analysis are discussed in the paper.

Loading frequency and temperature-dependent damping capacity of NiTiHfPd shape memory alloy

2020 ◽  
Vol 150 ◽  
pp. 103565
Author(s):  
Guher P. Toker ◽  
Soheil Saedi ◽  
Emre Acar ◽  
Osman E. Ozbulut ◽  
Haluk E. Karaca
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Damping Capacity ◽  
Loading Frequency ◽  
Temperature Dependent

Numerical simulation of safety device executive element of the shape memory alloy for a safe electrical outlet

2019 ◽  
Author(s):  
S.M. Ganysh
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Nonlinear Differential Equations ◽  
Phenomenological Approach ◽  
Internal Force ◽  
Material Behavior ◽  
Transition Diagram ◽  
The Relationship

The article considers possibility of creating a safety element for a safe electrical outlet based on the shape memory effect. Numerical model of helical cylindrical spring of the shape memory alloy is developed. The phenomenological approach based on the phase transition diagram is used to describe material behavior. Shape memory effect is included using additional internal force factor i.e. the shape memory moment under torsion. An algorithm for constructing the relationship between the torque in cross section and the shape memory moment for isothermal loading is presented. The problem of simultaneous deformation of shape memory alloy spring and flat copper spring under heating is solved. The contact plate is replaced by an equivalent spring. Spring stiffness is obtained using a system of nonlinear differential equations describing the bending of a bar.

Shape memory alloy actuators in smart structures: Modeling and simulation

2004 ◽  
Vol 57 (1) ◽  
pp. 23-46 ◽  
Author(s):  
Stefan Seelecke ◽  
Ingo Mu¨ller
Keyword(s):  
Optimal Control ◽  
Shape Memory Alloy ◽  
Modeling And Simulation ◽  
Shape Memory ◽  
Smart Structures ◽  
Review Article ◽  
Material Behavior ◽  
Control Methods ◽  
Time Optimal ◽  
And Control

This review article gives an overview of the new and quickly developing field of shape memory alloy (SMA) actuators in smart structures. The focus is on the aspects of modeling and simulation of such structures, a task that goes beyond classical modeling approaches as it has to combine constitutive modeling with structural and control aspects in a highly interdisciplinary way. We review developments in each of these fields, trying to combine them into a smooth picture of how to treat the problem efficiently. After a discussion of modeling aspects with particular regard to actuator applications, the simulation of standard feedback control methods is demonstrated. Subsequently, model based methods from optimal control theory are presented, accounting for the strongly nonlinear and hysteretic material behavior of SMAs. Real-time optimal control methods are introduced and, finally, aspects of finite element implementation of an SMA actuator model are discussed and illustrated by the simulation of an adaptive aircraft wing. This review article cites 155 references.

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