Steerable Unidirectional Wave Emission From a Single Piezoelectric Transducer Using a Shape Memory Alloy Composite Metasurface

2020 ◽  
Author(s):  
Yihao Song ◽  
Yanfeng Shen
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Excitation Frequency ◽  
Element Model ◽  
Martensite Phase ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Unit Cell ◽  
Wave Radiation ◽  
Wave Emission

Abstract Structural Health Monitoring (SHM) and Nondestructive Evaluation (NDE) systems generally adopt piezoelectric transducers which emit omnidirectional wave fields. The achievement of directionality of guided wave generation will benefit the structural sensing purpose, which allows better detection and localization of the damage sites. In this study, a type of metamaterial ultrasonic radar is proposed for the steerable unidirectional wave manipulation. It contains a circular array of unit cells stuck in an aluminum plate which are delicately arranged in a circular fashion. Each unit cell is composed of a shape memory alloy substrate and a lead stub. The controllable bandgap of such metamaterial system can be achieved due to the stiffness change of nitinol between its martensite phase and austenite phase under a thermal load. This research starts with a Finite Element Model (FEM) of the unit cell to compute its frequency-wavenumber domain dispersion characteristics, demonstrating the adjustable bandgap feature. Then, numerical modeling of the metamaterial radar is performed by shifting the bandgap of one sector of the metasurface away from the excitation frequency. The modeling results demonstrate that the martensite phase metasurface area forms a bandgap region where guided wave energy cannot penetrate, while the bandgap of the austenite sector shifts away from the excitation frequency, opening up a transmission path for the ultrasonic waves. By rotating the austenite sector, the metamaterial structure can work like a wave emission radar, realizing of the steerable unidirectional wave radiation with a single transducer. Such an active metasurface possesses great application potential in future SHM and NDE systems.

Programmable Waveguiding of Ultrasonic Waves for Regional Damage Detection Using Elastic Metamaterials

2020 ◽  
Author(s):  
Yihao Song ◽  
Yanfeng Shen
Keyword(s):  
Damage Detection ◽  
Shape Memory ◽  
Excitation Frequency ◽  
Element Model ◽  
Martensite Phase ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Unit Cell ◽  
Propagation Path ◽  
Rectangular Array

Abstract This study puts forward a metasurface design which allows the flexible tuning of the elastic wave propagation path, enabling the interrogating wave field guiding into desired monitoring regions for damage detection. As a demonstrative case study, the metasurface plate contains a rectangular array of unit cells sitting in an aluminum plate. Each unit cell is comprised of a shape memory alloy substrate and a lead stub. The controllable bandgap of such a metamaterial system can be achieved due to the stiffness change of nitinol between its martensite phase and austenite phase under a thermal load. First, a Finite Element Model (FEM) of the unit cell is constructed to calculate the band structure of the metasurface plate, demonstrating the adjustable bandgap behavior. Then, numerical modeling of the metamaterial waveguide is performed by shifting the bandgap of a specific path of the metasurface away from the excitation frequency. The modeling results demonstrate that the martensite metasurface area forms a bandgap region where guided wave energy cannot penetrate. While, the bandgap of the austenite part shifts away from the excitation frequency, opening up a transmission path for the ultrasonic waves. By delicately selecting the austenite state unit cell path, four ‘S’, ‘J’, ‘T’, ‘U’ shaped routes with a fine resolution are tailored to show a SJTU logo, demonstrating the excellent waveguiding capability and the programmable waveguide feature of this shape memory metamaterial system. The proposed tunable waveguiding methodology possesses great application potential in future Structural Health Monitoring (SHM) and Nondestructive Evaluation (NDE) applications.

Nonlinear two-dimensional finite element model for transient and damping analysis of cylindrical sandwich panels with pseudoelastic shape memory alloy composite face sheets

2017 ◽  
Vol 21 (1) ◽  
pp. 19-76 ◽  
Author(s):  
Maryam Khanjani ◽  
Mahmoud Shakeri ◽  
Mojtaba Sadighi
Keyword(s):  
Finite Element ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Volume Fraction ◽  
Element Model ◽  
Martensite Phase ◽  
Governing Equations ◽  
Time Step ◽  
Composite Face

A new nonlinear finite element model is proposed for the dynamic analysis of cylindrical sandwich panels with shape memory alloy hybrid composite face sheets and flexible core. In order to present a realistic transient vibration analysis, all the material complexities arising from the instantaneous and spatial martensite phase transformation of the shape memory alloy wires are taken into consideration. The one-dimensional constitutive equation proposed by Boyd and Lagoudas is used for modeling the pseudoelastic behavior of the shape memory alloy wires. Since the martensite volume fraction at each point depends on the stress at that point, the phase transformation kinetic equations and the governing equations are coupled together. Therefore, at each time step, an iterative method should be used to solve the highly nonlinear equations. Moreover, considering that the stress resultants generated by the martensite phase transformation in the wires are path-dependent values, an incremental method is used to estimate the increment of the stress resultants at each time step. The governing equations are derived based on the energy method and Newmark time integration method is used to solve the discretized finite element equations. Finally, several numerical examples are presented to examine the effect of various parameters such as intensity of applied pressure load, operating temperature, location of shape memory alloy wires, volume fraction of the shape memory alloy wires, and also boundary conditions upon the loss factor for panels with different aspect ratios.

In Situ TEM Observation of Phase Transformation for Bio-Medical Shape Memory TiNbSn Alloy

2010 ◽  
Vol 152-153 ◽  
pp. 1755-1758
Author(s):  
Yan Li ◽  
Jie Qi ◽  
Rui Rui Fan ◽  
Chuan Xin Zhai ◽  
Chun Hua Xu
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Shape Memory ◽  
Martensite Phase ◽  
Unit Cell ◽  
Niti Shape Memory Alloy ◽  
Transformation Mechanism ◽  
Cell Parameters ◽  
Β Phase

TiNbSn alloy has high specific strength, low modulus of elasticity, excellent corrosion resistance, no side effects, such as toxic and exhibits shape memory effects after appropriate technical processing. This alloy may substitute as NiTi shape memory alloy to become the new generation of biological materials. It has been reported the studies of this alloy, such as the component and proportion, processing technology, mechanical properties and corrosion resistance. Based on the previous research, the bio-metal material, Ti-10Nb-5Sn alloy was heated and cooled repeatedly in a heater system located in TEM chamber and, at the same time, was observed in situ using a high resolution transmission electron microscope to study the memory property of the alloy and the mechanism of the transformation between austenite β and martensite phase. The results show that, during heating stage from 295K to 400K, the martensite began to dissolve at 355K, and the martensite disappeared completely at 385K, meanwhile, the austenite was created. During cooling stage from 400K to 295K, the martensite begins to take shape at 353K and the transformation was completed at 333K. The alloy can memory the room and high temperature structures, showing two-way memory functions. The high-temperature austenite of Ti-10Nb-5Sn alloy shows body-centered cubic β phase with the unit cell parameter a=0.3283nm; the martensite at room temperature shows orthorhombic NbTi4 phase (M) with the unit cell parameters a=0.3152nm, b=0.4854nm, c=0.4642nm. The orientation relationship between M phase and β phase is , , , , and . The crystal plane , as the habit plane, transforms into during the transformation from β to M phases. The martensite transformation mechanism is that the and transform to and through the tiny migration of atoms.

Experimental characterization and control of a magnetic shape memory alloy actuator using the modified generalized rate-dependent Prandtl–Ishlinskii hysteresis model

2018 ◽  
Vol 232 (5) ◽  
pp. 506-518 ◽  
Author(s):  
Saeid Shakiba ◽  
Mohammad Reza Zakerzadeh ◽  
Moosa Ayati
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Excitation Frequency ◽  
Hysteresis Loops ◽  
Experimental Results ◽  
Hysteretic Behavior ◽  
Magnetic Shape Memory ◽  
Shape Memory Alloy Actuator ◽  
Rate Dependent ◽  
Magnetic Shape Memory Alloy

In this article, two models are used, namely rate-independent and rate-dependent generalized Prandtl–Ishlinskii, to characterize a magnetic shape memory alloy actuator. The results show that the rate-independent model cannot consider the effect of input excitation frequency, while the rate-dependent model omits this drawback by defining a time-dependent operator. For the first time, the effects of excitation frequency on the hysteretic behavior of magnetic shape memory alloy actuator are investigated. In this study, five excitation voltages with different frequencies in the range of 0.05–0.4 Hz are utilized as inputs to the magnetic shape memory alloy actuator and the displacement outputs are measured. Experimental results indicate that, with increasing the excitation frequency, the size of the hysteresis loops changes. Since the generalized rate-dependent Prandtl–Ishlinskii model cannot consider the asymmetric hysteresis loops, in the developed model, a tangent hyperbolic function is applied as an envelope function in order to improve the capability of the model in characterizing the asymmetric behavior of magnetic shape memory alloy actuator. The parameters of both rate-dependent and rate-independent models are identified by genetic algorithm optimization. The results reveal that the rate-independent form is not capable of accurately describing the hysteretic behavior of magnetic shape memory alloy actuator for different input frequencies. Simulation and experimental results also demonstrate the proficiency of the developed model for precise characterization of the saturated rate-dependent hysteresis loops of magnetic shape memory alloy actuator. In addition, the proposed model is utilized for determining a proper range for controller coefficients during controller design.

Mössbauer study on martensite phase in Ni50Mn36.5Fe0.557Sn13 metamagnetic shape memory alloy

2008 ◽  
Vol 93 (4) ◽  
pp. 042509 ◽  
Author(s):  
R. Y. Umetsu ◽  
R. Kainuma ◽  
Y. Amako ◽  
Y. Taniguchi ◽  
T. Kanomata ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Martensite Phase ◽  
Mössbauer Study

Study on Martensite Phase Transformation near Crack Tip of Mode II in Shape Memory Alloy

2011 ◽  
Vol 148-149 ◽  
pp. 875-878
Author(s):  
Bo Zhou ◽  
Jun Lv ◽  
Gang Ling Hou ◽  
Ya Ru Pan
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Crack Tip ◽  
Complex Stress ◽  
Martensite Phase ◽  
Complex Stress State ◽  
Transformation Model ◽  
Mode Ii ◽  
The One

In this paper, the phase transformation behaviors of shape memory alloy (SMA) in the complex stress state are formulated based the one-dimensional phase transformation model supposed by Zhou and Yoon. The stress field near the crack tip of mode II in SMA is described based on linear elastic fracture mechanics. The phase transformation behaviors of SMA near the crack tip of Mode II are numerically investigated.

Modeling and characterization of the shape memory alloy–based morphing wing behavior using proposed rate-dependent Prandtl-Ishlinskii models

2019 ◽  
Vol 234 (4) ◽  
pp. 550-565 ◽  
Author(s):  
Saeid Shakiba ◽  
Aghil Yousefi-Koma ◽  
Mehdi Jokar ◽  
Mohammad Reza Zakerzadeh ◽  
Hamid Basaeri
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Dead Zone ◽  
Excitation Frequency ◽  
Experimental Results ◽  
Frequency Effect ◽  
Rate Dependency ◽  
Unknown Parameters ◽  
Hysteresis Behavior ◽  
Rate Dependent

Unique features of shape memory alloys make them a proper actuation choice in various control systems. However, their nonlinear hysteresis behavior negatively affects wide utilization of such materials in structure actuation. In this study, the frequency effect on the hysteresis behavior of a shape memory alloy–actuated structure is experimentally investigated, and also two proposed versions of rate-dependent Prandtl-Ishlinskii (modified rate-dependent Prandtl-Ishlinskii and revised modified rate-dependent Prandtl-Ishlinskii) are presented, which are capable of characterizing this phenomenon. Experimental results show that increasing excitation frequency leads to bigger hysteresis loops. It is also proven that rate-dependency cannot be predicted by generalized Prandtl-Ishlinskii model. In addition, a comparison between the dead zone function-based rate-dependent Prandtl-Ishlinskii model as an only benchmark model and the proposed models have been done that proves the proposed models’ superiority. In addition, genetic algorithm is exploited to identify unknown parameters of all models. Trained models performance is also experimentally evaluated at different input frequencies. Comparison between simulation and experimental results indicates that the proposed models can reliably predict saturated, asymmetric, rate-dependent hysteresis behavior, and minor loops in shape memory alloy–embedded actuators.

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