Exploitation of Large Recoverable Deformations Using Weaved Shape Memory Alloy Wire-Based Sandwich Panel Configurations

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Ashish Mohan ◽  
Sivakumar M. Srinivasan ◽  
Makarand Joshi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Static Load ◽  
Permanent Deformation ◽  
Element Model ◽  
Truss Structure ◽  
Truss Structures ◽  
Compressive Response ◽  
New Class ◽  
Pyramidal Configuration

A new class of truss structure based on superelastic shape memory alloy (SMA) wire has been developed by weaving superelastic SMA wire through two perforated facesheets. A gap was maintained between the facesheets while weaving and the ends of wire forming the truss legs are anchored in each facesheet. The resulting structure has a modified pyramidal configuration and is capable of undergoing large recoverable deformations typical of superelastic SMA. A four-unit cell truss specimen has been tested under static load cycles to investigate the compressive response. The truss specimen underwent a hysteretic loop and demonstrated minimal permanent deformation closely resembling the behavior of bulk SMA. A finite element model of the truss was generated and the analysis results were compared with the experimental response. The present work is an attempt to demonstrate an SMA-based truss structure having energy absorption capabilities with minimum permanent deformation. These truss structures may be applied for damage mitigation in composites subjected to impact and blast loads.

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.

scholarly journals Active Adjustment of Surface Accuracy for a Large Cable-Net Structure by Shape Memory Alloy

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2619
Author(s):  
Xiangjun Jiang ◽  
Fengqun Pan ◽  
Yesen Fan ◽  
Jingli Du ◽  
Mingbo Zhu ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Surface ◽  
Element Model ◽  
Optimization Method ◽  
Space Environment ◽  
Antenna Structure ◽  
Adjustment Procedure ◽  
Surface Accuracy ◽  
Parabolic Reflectors

The high surface accuracy design of a cable-net antenna structure under the disturbance of the extremely harsh space environment requires the antenna to have good in-orbit adjustment ability for surface accuracy. A shape memory cable-net (SMC) structure is proposed in this paper and believed to be able to improve the in-orbit surface accuracy of the cable-net antenna. Firstly, the incremental stiffness equation of a one-dimensional bar element of the shape memory alloy (SMA) to express the relationship between the force, temperature and deformation was effectively constructed. Secondly, the finite element model of the SMC antenna structure incorporated the incremental stiffness equation of a SMA was established. Thirdly, a shape active adjustment procedure of surface accuracy based on the optimization method was presented. Finally, a numerical example of the shape memory cable net structure applied to the parabolic reflectors of space antennas was analyzed.

Thermomechanical Modelling and Experimental Testing of a Shape Memory Alloy Hybrid Composite Plate

2008 ◽  
Vol 59 ◽  
pp. 41-46 ◽  
Author(s):  
Federica Daghia ◽  
Gabriella Faiella ◽  
Vincenza Antonucci ◽  
Michele Giordano
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Finite Element Model ◽  
Shape Memory ◽  
Functional Properties ◽  
Hybrid Composite ◽  
Experimental Testing ◽  
Element Model ◽  
Electrical Heating ◽  
Simultaneous Generation

Shape memory alloys (SMA) exhibit functional properties associated with the shape memory effect, responsible of the SMA shape recovery after a cycle of deforming-heating and of a simultaneous generation of mechanical work. Composite systems incorporating SMA wires have the ability to actively change shape and other structural characteristics. The functional properties of such adaptive composites are related to the martensitic transformation in the SMA elements and to the constraining behaviour that the composite matrix has on the SMA wires. In this work the behaviour of a shape memory alloy hybrid composite (SMAHC) is numerically and experimentally investigated. A plate was fabricated using prestrained SMA wires embedded in an epoxy resin pre preg glass fibres composite system. Upon calorimetric and mechanical material characterization, a finite element model was used in order to predict the structural behaviour of the SMAHC. In the experimental tests, the plate was clamped at one side and actuated via electrical heating. Temperature and displacement data were collected and compared with the prediction of the finite element model. The results show that the model is able to capture the shape change in the actuation region, although a thorough description of the SMAHC behaviour requires further modelling work, including the simulation of the SMA loading history during composite manufacturing.

Intelligent Monitoring Technique for Working Status of Shenzhen Citizen Center Roof Truss Structure under Wind Load

2008 ◽  
Vol 33-37 ◽  
pp. 1141-1148 ◽  
Author(s):  
Hui Liu ◽  
Wei Lian Qu ◽  
Jin Wen Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Wind Load ◽  
Truss Structure ◽  
Truss Structures ◽  
Intelligent Monitoring ◽  
Peak Factor ◽  
Acceleration Sensors ◽  
Working Status

Taken the roof of Shenzhen citizen center with huge size and very complicated structure as the engineering background, the intelligent methods of safety monitoring of integer behavior for large span complex space truss structures under wind-excited by the data-acquisition based on limited sensors are discussed in detail in this paper. In order to acquire the working status of the whole structure, the method that can be adopted to obtain structural real-time response under wind load is listed as follows, step1: to identify the wind load; step 2: to update the structural finite element model; step 3: to measure peak factor of structural response; step 4: to directly analyze the structural real timely response. The first two steps are key techniques among all the steps of the method. The weighted proper orthogonal decomposition technique is adopted to identify the characteristics of wind pressures at all internal nodes on the truss structural roof in the frequency domain by using the measured wind pressure data from non-uniformly taps. Moreover, by using measured structural acceleration response from finite acceleration sensors on the structure, the accurate analytical model of the structure is established by updating the finite element model based on modifying node parameters. Then, the monitoring result of entire truss structure in the worst working performance in every ten minutes is obtained according to positive deductive method with the measured mean wind speed and wind direction from anemometer and peak factor acquired from finite strain gauges on the truss structure in every 10 minutes. Finally, based on the above-mentioned method, working status intelligent monitoring system is established, which can display the stress level and safe class of all structural members.

Development of a shape memory alloy multiple-point injector for chemotherapy

2005 ◽  
Vol 219 (3) ◽  
pp. 213-217 ◽  
Author(s):  
W Xu ◽  
T G Frank ◽  
A Cuschieri
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Direct Injection ◽  
Element Model ◽  
Multiple Point ◽  
Linear Elastic ◽  
Outer Needle ◽  
Non Linear ◽  
Deformation Force ◽  
Medical Needle

A medical needle is described that allows injection to take place at multiple sites through a single stab wound. This is achieved by extruding multiple, thin, and curved internal needles from a larger, straight, outer needle. The development and finite element modelling of the shape memory alloy (SMA) inner needles is presented in this paper. A non-linear elastic element model was used in this process to allow for the non-linear properties of the alloy and the large deformations that occur. The model provided maximum strain values and penetration forces for the inner needles. The deformation force on the tip of the needle was measured against displacement to confirm the predicted penetration force. Applications for the device include the treatment of liver cancer by direct injection of alcohol into the tumours.

Numerical investigation on the cyclic behavior of smart recentering clip-angle connections with superelastic shape memory alloy fasteners

2012 ◽  
Vol 227 (6) ◽  
pp. 1315-1327 ◽  
Author(s):  
Jong Wan Hu ◽  
Dong Keon Kim ◽  
Eunsoo Choi
Keyword(s):  
Plastic Deformation ◽  
Numerical Analysis ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Permanent Deformation ◽  
Cyclic Behavior ◽  
Bolted Connections ◽  
Joint Models ◽  
Mechanical Joint ◽  
Total Displacement

Superelastic shape memory alloy materials have become increasingly prevalent for recentering devices that have the ability to recover their plastic deformation automatically. For this reason, this study proposed new clip-angle connections incorporating superelastic shape memory alloy bolts. Including component spring models, mechanical joint models of steel bolted connections and shape memory alloy bolted connections are created for numerically simulating their cyclic behavior. The numerical analysis results are then compared to each other in terms of ultimate strength, energy dissipation, and permanent deformation. In particular, over 60% of the total displacement was recovered during unloads in case of shape memory alloy bolted connections, indicating that the proposed smart connections display obvious recentering features in their behaviors.

An Application for Superelastic Material in a Passive Inertial Damage Sensor for Detection of Conditions Leading to the Accumulation of Hidden Structural Damage Caused by Transient Loading in Aircraft The Conception

2004 ◽  
Vol 1 (2) ◽  
pp. 72-94
Author(s):  
J. Hoffman ◽  
R. Jeffers
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Structural Damage ◽  
Preventive Measures ◽  
Permanent Deformation ◽  
Engineering Profession ◽  
Accumulation Of Damage ◽  
And Performance ◽  
Inspection Techniques ◽  
Mechanical Disturbances

The unusual properties of shape memory alloy have long tempted the engineering profession with its apparent possibilities. In this paper an aspect of shape memory, augmented by the property of superelasticity, is considered for use in sensing the occurrence of mechanical disturbances having severity sufficient to cause major damage within airborne structure or electronic modules. Often this damage occurs internally, i.e. below structure surfaces and thus is essentially invisible to inspection techniques that are performed in normal maintenance operations. The concept of a sensor is presented, herein, that can act as a witness to the occurrence of conditions that can produce such structural damage. The sensor, being passive in nature, carries its message in the permanent deformation of internal structure that is to be inspected at convenient intervals, between aircraft flights or after occurrence of seemingly severe aerodynamic or mechanical disturbances are encountered, to indicate the maximum levels of acceleration that it has witnessed. On the basis of such information, timely maintenance measures can be made to prevent impending failures from taking place. The location of such a sensor would serve to locate particular structure or components that would be susceptible to damage from the sensed levels of acceleration. This serves to focus maintenance inspection processes and indicate immediate preventive measures to be taken through replacement of, certain likely damaged structure, before the damage can accumulate to threaten the safety of the aircraft. The sensor concept is described herein, along with its expected properties and performance. This paper presents: (1) The basis for a general need for such a sensor; (2) A description of the sensor mechanization; (3) Aspects of shape memory and superelasticity relevant to its conception and purpose; (4) Test data illustrating the properties of the material and how they may be used to prevent further accumulation of damage; (5) Feasibility considerations in support of the concept and (6) Conclusions and objectives for continuing work.

Modeling of Artificial Aurelia aurita Bell Deformation

2011 ◽  
Vol 45 (4) ◽  
pp. 165-180 ◽  
Author(s):  
Keyur B. Joshi ◽  
Alex Villanueva ◽  
Colin F. Smith ◽  
Shashank Priya
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Transient Behavior ◽  
Element Model ◽  
Aurelia Aurita ◽  
Thermal Coefficient ◽  
Power Cycle ◽  
Element Simulation ◽  
The Difference

AbstractRecently, there has been significant interest in developing underwater vehicles inspired by jellyfish. One of these notable efforts includes the artificial Aurelia aurita (Robojelly). The artificial A. aurita is able to swim with similar proficiency to the A. aurita species of jellyfish even though its deformation profile does not completely match the natural animal. In order to overcome this problem, we provide a systematic finite element model (FEM) to simulate the transient behavior of the artificial A. aurita vehicle utilizing bio-inspired shape memory alloy composite (BISMAC) actuators. The finite element simulation model accurately captures the hyperelastic behavior of EcoFlex (Shore hardness-0010) room temperature vulcanizing silicone by invoking a three-parameter Mooney-Rivlin model. Furthermore, the FEM incorporates experimental temperature transformation curves of shape memory alloy wires by introducing negative thermal coefficient of expansion and considers the effect of gravity and fluid buoyancy forces to accurately predict the transient deformation of the vehicle. The actual power cycle used to drive artificial A. aurita vehicle was used in the model. The overall profile error between FEM and the vehicle profile is mainly due to the difference in initial relaxed profiles.

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