Modeling and Experimental Validation of Shape Memory Alloy Bending Actuators

2012 ◽  
Author(s):  
Casey D. Haigh ◽  
John H. Crews ◽  
Shiquan Wang ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Performance Optimization ◽  
Experimental Validation ◽  
Design Tool ◽  
Design Parameters ◽  
Bending Performance ◽  
Critical Design ◽  
Section Modulus ◽  
Composite Actuator

In this paper, we develop a computational model that can be used to investigate and optimize the performance of shape memory alloy (SMA) bending actuators. These actuators (approximately 7–21 mm in length) consist of curved SMA wires embedded within elastic sleeves and are intended for positioning and anchoring robotic catheters inside blood vessels during clinical treatments. Each SMA wire is shape-set to an initial curvature and inserted along the neutral axis of a straight elastic member (cast heat-resistant silicone with varying section modulus). The elastic member preloads the SMA (or produces a stress-induced phase transformation), reducing the equilibrium curvature of the composite actuator. Temperature-induced phase transformations in the SMA (via Joule heating) enable strain recovery and increased bending (increased curvature) in the composite actuator. The homogenized energy framework is utilized to model the behavior of this composite actuator, and the effects of several critical design parameters (initial SMA curvature and section modulus of the elastic member) on the deactivated and activated curvatures are investigated. Experimental results validate the model, enabling its use as a design tool for bending performance optimization.

scholarly journals Multi-Objective Design Optimization of a Shape Memory Alloy Flexural Actuator

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 13 ◽  
Author(s):  
Casey D. Haigh ◽  
John H. Crews ◽  
Shiquan Wang ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Design Optimization ◽  
Flexural Rigidity ◽  
Pareto Frontier ◽  
Design Parameters ◽  
Optimization Strategy ◽  
Multi Objective ◽  
Critical Design ◽  
Multi Objective Genetic Algorithm

This paper presents a computational model and design optimization strategy for shape memory alloy (SMA) flexural actuators. These actuators consist of curved SMA wires embedded within elastic structures; one potential application is positioning microcatheters inside blood vessels during clinical treatments. Each SMA wire is shape-set to an initial curvature and inserted along the neutral axis of a straight elastic member (cast polydimethylsiloxane, PDMS). The elastic structure preloads the SMA, reducing the equilibrium curvature of the composite actuator. Temperature-induced phase transformations in the SMA are achieved via Joule heating, enabling strain recovery and increased bending (increased curvature) in the actuator. Actuator behavior is modeled using the homogenized energy framework, and the effects of two critical design parameters (initial SMA curvature and flexural rigidity of the elastic sleeve) on activation curvature are investigated. Finally, a multi-objective genetic algorithm is utilized to optimize actuator performance and generate a Pareto frontier, which is subsequently experimentally validated.

Corrugated structures reinforced by shape memory alloy sheets: Analytical modeling and finite element modeling

2018 ◽  
Vol 233 (7) ◽  
pp. 2445-2454 ◽  
Author(s):  
Maryam Koudzari ◽  
Mohammad-Reza Zakerzadeh ◽  
Mostafa Baghani
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Finite Element Modeling ◽  
Shape Memory ◽  
Smart Structure ◽  
Design Parameters ◽  
Asymmetric Mode ◽  
Element Modeling ◽  
Structure Changes

In this study, an analytical solution is presented for a trapezoidal corrugated beam, which is reinforced by shape memory alloy sheets on both sides. Formulas are presented for shape memory alloys in states of compression and tension. According to the modified Brinson model, shape memory alloys have different thermomechanical behavior in compression and tension, and also these alloys would behave differently in different temperatures. The developed formulation is based on Euler–Bernoulli theory. Deflection of the smart structure and the effect of asymmetric response in shape memory alloys are studied. Results found from the semi-analytic modeling are compared to and validated through a finite element modeling, and there is more than [Formula: see text] agreement between two solutions. With regard to the results, the neutral axis of the smart structure changes in each section. The maximum deflection ratio of asymmetric mode to symmetric one mode is 1.7. Additionally, the effect of design parameters on deflection is studied in detail.

Wet Shape Memory Alloy Actuated Robotic Heart

2009 ◽  
Author(s):  
Joel Ertel ◽  
Stephen Mascaro
Keyword(s):  
Shape Memory Alloy ◽  
Theoretical Analysis ◽  
Shape Memory ◽  
Preliminary Analysis ◽  
Design Concept ◽  
Design Parameters ◽  
Sma Actuators ◽  
Fluid Analysis ◽  
Cold Fluid ◽  
Simulation And Experiment

This paper presents a conceptual design and preliminary analysis for a biomimetic robotic heart. The purpose of the robotic heart is to distribute hot and cold fluid to robotic muscles composed of wet shape-memory alloy (SMA) actuators. The robotic heart is itself powered by wet SMA actuators. A heart design concept is proposed and the feasibility of self-sustaining motion is investigated through simulation and experiment. The chosen design employs symmetric pumping chambers for hot and cold fluid. Analysis of this design concept shows that there exists a range of design parameters that will allow the heart to output more fluid than it uses. Additionally, it is shown that the heartbeat rate decreases as the system increases in size, and that the number of actuators and their length limit the power output of the pump. Experimental results from a prototype heart agree with the predicted trends from theoretical analysis and simulation.

scholarly journals Optimal Design of Shape Memory Alloy Composite under Deflection Constraint

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1733 ◽  
Author(s):  
Yogesh Gandhi ◽  
Alessandro Pirondi ◽  
Luca Collini
Keyword(s):  
Optimal Design ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Optimization Problem ◽  
Edge Length ◽  
Design Parameters ◽  
Stable Configuration ◽  
Alloy Composite ◽  
Bistable Behavior ◽  
Design Variables

Shape-adaptive or morphing capability in both aerospace structures and wind turbine blade design is regarded as significant to increase aerodynamic performance and simplify mechanisms by reducing the number of moving parts. The underlying bistable behavior of asymmetric cross-ply composites makes them a suitable candidate for morphing applications. To date, various theoretical and experiential studies have been carried out to understand and predict the bistable behavior of asymmetric laminates and especially the curvature obtained in their stable configurations. However, when the bi-stable composite plate is integrated with shape memory alloy wires to control the curvature and to snap from a stable configuration to the other (shape memory alloy composite, SMAC), the identification of the design parameters, namely laminate edge length, ply thickness and ply orientation, is not straightforward. The aim of this article is to present the formulation of an optimization problem for the parameters of an asymmetric composite laminate integrated with pre-stressed shape memory alloys (SMA) wires under bi-stability and a minimum deflection requirement. Wires are modeled as an additional ply placed at the mid-plane of the composite host plate. The optimization problem is solved numerically in MATLAB and optimal design variables are then used to model the SMAC in ABAQUS™. Finite element results are compared against numerical results for validation.

scholarly journals Engineering Design Tools for Shape Memory Alloy Actuators: CASMART Collaborative Best Practices and Case Studies

2016 ◽  
Author(s):  
Robert W. Wheeler ◽  
Othmane Benafan ◽  
Xiujie Gao ◽  
Frederick T. Calkins ◽  
Zahra Ghanbari ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Best Practices ◽  
Shape Memory ◽  
Case Studies ◽  
Design Parameters ◽  
Solar Array ◽  
Design Tools ◽  
Modeling Framework ◽  
Modeling Tools ◽  
Actuation System

The primary goal of the Consortium for the Advancement of Shape Memory Alloy Research and Technology (CASMART) is to enable the design of revolutionary applications based on shape memory alloy (SMA) technology. In order to help realize this goal and reduce the development time and required experience for the fabrication of SMA actuation systems, several modeling tools have been developed for common actuator types and are discussed herein along with case studies, which highlight the capabilities and limitations of these tools. Due to their ability to sustain high stresses and recover large deformations, SMAs have many potential applications as reliable, lightweight, solid-state actuators. Their advantage over classical actuators can also be further improved when the actuator geometry is modified to fit the specific application. In this paper, three common actuator designs are studied: wires, which are lightweight, low-profile, and easily implemented; springs, which offer actuation strokes upwards of 200% at reduced mechanical loads; and torque tubes, which can provide large actuation forces in small volumes and develop a repeatable zero-load actuation response (known as the two-way shape memory effect). The modeling frameworks, which have been implemented in the design tools, are developed for each of these frequently used SMA actuator types. In order to demonstrate the versatility and flexibility of the presented design tools, as well as validate their modeling framework, several design challenges were completed. These case studies include the design and development of an active hinge for the deployment of a solar array or foldable space structure, an adaptive solar array deployment and positioning system, a passive air temperature controller for the regulation of flow temperatures inside of a jet engine, and a redesign of the Corvette active hatch, which allows for pressure equalization of the car interior. For each of the presented case studies, a prototype or proof-of-concept was fabricated and the experimental results and lessons learned are discussed. This analysis presents a collection of CASMART collaborative best practices in order to allow readers to utilize the available design tools and understand their modeling principles. These design tools, which are based on engineering models, can provide first-order optimal designs and are a basic and efficient method for either demonstrating design feasibility or refining design parameters. Although the design and integration of an SMA-based actuation system always requires application- and environment-specific engineering considerations, common modeling tools can significantly reduce the investment required for actuation system development and provide valuable engineering insight.

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