Systems Actuated by Shape Memory Alloys: Identification and Modeling

2021 ◽  
Vol 1 (2) ◽  
pp. 12-20
Author(s):  
Najmeh Keshtkar ◽  
Johannes Mersch ◽  
Konrad Katzer ◽  
Felix Lohse ◽  
Lars Natkowski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Numerical Simulations ◽  
Shape Memory ◽  
Transfer Equation ◽  
Mechanical Parameters ◽  
Heat Transfer Equation ◽  
The Mathematical Model

This paper presents the identification of thermal and mechanical parameters of shape memory alloys by using the heat transfer equation and a constitutive model. The identified parameters are then used to describe the mathematical model of a fiber-elastomer composite embedded with shape memory alloys. To verify the validity of the obtained equations, numerical simulations of the SMA temperature and composite bending are carried out and compared with the experimental results.

Boubaker Polynomials Expansion Scheme Solution to the Heat Transfer Equation Inside Laser Heated Biological Tissues

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. A. Aweda ◽  
M. Agida ◽  
M. Dada ◽  
O. B. Awojoyogbe ◽  
K. Isah ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Analytical Solution ◽  
Numerical Simulations ◽  
Laser Heating ◽  
Transfer Equation ◽  
Biological Tissues ◽  
Heat Transfer Equation ◽  
Boubaker Polynomials ◽  
Laser Heated ◽  
Expansion Scheme

In this study, an analytical solution to the heat transfer equation in biological tissues during laser heating is presented. The results were compared to recently published numerical simulations.

Research on Heat Distribution in a Thermal Insulation Space and a Kind of Evaluation Involving Heat-Distribution and Valid Heating-Area

2013 ◽  
Vol 444-445 ◽  
pp. 1427-1433
Author(s):  
Hong Yang Jin ◽  
Zhi Hua Chen ◽  
Lang Li
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Standard Deviation ◽  
Thermal Insulation ◽  
Transfer Equation ◽  
Heating Process ◽  
Heat Distribution ◽  
Heat Transfer Equation ◽  
Heat Transmission

Considering that food always be spoiled in an oven, an analysis of the heat distribution of an object (pan) in a thermal insulation space has been done. The analysis based on the characteristics of heat transmission in an oven. A mathematical model is designed to illustrate the heating process. Specifically, in order to monitor the temperature of the object, pdetool in MATLAB is used to solve the heat transfer equation. Then to evaluate how an object performs in the oven, a method of standard deviation has been introduced. For the efficiency, valid heating area should also be considered. Thus an evaluation is made to choose a most preferring pan, which is balanced between heat distribution and valid heating area (number of pans). The experiment shows that shapes would devote much in performance. It is also demonstrated that there is a certain shape that can be most suitable to be a pan.

scholarly journals Bifurcations and Crises in a Shape Memory Oscillator

2004 ◽  
Vol 11 (2) ◽  
pp. 67-80 ◽  
Author(s):  
Luciano G. Machado ◽  
Marcelo A. Savi ◽  
Pedro M.C.L. Pacheco
Keyword(s):  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Numerical Simulations ◽  
Shape Memory ◽  
Period Doubling ◽  
Dynamical Response ◽  
Nonlinear Characteristics ◽  
Bifurcation Phenomenon ◽  
Shape Memory Actuators ◽  
Qualitative Changes

The remarkable properties of shape memory alloys have been motivating the interest in applications in different areas varying from biomedical to aerospace hardware. The dynamical response of systems composed by shape memory actuators presents nonlinear characteristics and a very rich behavior, showing periodic, quasi-periodic and chaotic responses. This contribution analyses some aspects related to bifurcation phenomenon in a shape memory oscillator where the restitution force is described by a polynomial constitutive model. The term bifurcation is used to describe qualitative changes that occur in the orbit structure of a system, as a consequence of parameter changes, being related to chaos. Numerical simulations show that the response of the shape memory oscillator presents period doubling cascades, direct and reverse, and crises.

Mathematical Model of the Bridgman-Stockbarger Method to Growth Semiconductor Single Crystals

1992 ◽  
Vol 278 ◽  
Author(s):  
E. Vega ◽  
G. Muiñiz ◽  
F. Rabago
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Single Crystals ◽  
Transfer Equation ◽  
Point System ◽  
Two Dimensional ◽  
Heat Transfer Equation ◽  
Stability Problems ◽  
Stockbarger Method ◽  
Dimensional Equation

AbstractA two dimensional equation has been solved which represents the heat transfer equation for the growth of single crystals system called Bridgman- Stockbarger method. Two variations were analyzed with and without an insulation between heater and cooler. System without an insulation shows stability problems because it's directly affected by the boundary between the cooler and heater region, in this case we obtained a discontinuity in this point. System with an insulation shows higher stability.

Modeling of Internal Damage Evolution During Actuation Fatigue in Shape Memory Alloys

2018 ◽  
Author(s):  
Francis R. Phillips ◽  
Daniel Martin ◽  
Dimitris C. Lagoudas ◽  
Robert W. Wheeler
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Damage Evolution ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Internal Damage ◽  
Functional Fatigue ◽  
Non Linear

Shape memory alloys (SMAs) are unique materials capable of undergoing a thermo-mechanically induced, reversible, crystallographic phase transformation. As SMAs are utilized across a variety of applications, it is necessary to understand the internal changes that occur throughout the lifetime of SMA components. One of the key limitations to the lifetime of a SMA component is the response of SMAs to fatigue. SMAs are subject to two kinds of fatigue, namely structural fatigue due to cyclic mechanical loading which is similar to high cycle fatigue, and functional fatigue due to cyclic phase transformation which typical is limited to the low cycle fatigue regime. In cases where functional fatigue is due to thermally induced phase transformation in contrast to being mechanically induced, this form of fatigue can be further defined as actuation fatigue. Utilizing X-ray computed microtomography, it is shown that during actuation fatigue, internal damage such as cracks or voids, evolves in a non-linear manner. A function is generated to capture this non-linear internal damage evolution and introduced into a SMA constitutive model. Finally, it is shown how the modified SMA constitutive model responds and the ability of the model to predict actuation fatigue lifetime is demonstrated.

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