Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators (original) (raw)
Related papers
Optimum placement of shape memory alloy wire actuator
Shape memory alloy wire actuators can be used in combination with compliant structures to attain desired force and displacement capabilities. The wires can be placed inside a matrix, as in composite, or outside the material connected at different points on the structure. In the latter case, the offset of the wire and the location of the points decides the overall deformation of the structure. In this article we study the effects of offset distance, and the number of points, called attachments, where the shape memory alloy wire is connected to a host beam. First the characteristic curve of the shape memory alloy wire actuator is derived from a constrained recovery model. Then the response of a beam model, undergoing large deflection due to follower forces, is superposed with the characteristic curve to obtain the maximum beam deformation. It is found that there exists a particular offset, called optimum offset, for which the deformation of the host is maximum. Moreover, the ratio of stress and change in strain in the shape memory alloy corresponding to the optimum offset, attains a particular value, irrespective of the flexural rigidities of the beam. Furthermore, it has been observed that for a set of beams that have flexural rigidity less than a particular value, the deformation increases with number of attachments. However, for the beams that have flexural rigidity more than that particular value, the deformation remains almost unaltered with number of attachments. These numerical results are also supported qualitatively by the experimental observations.
Flexible Shape-Memory Alloy-Based Actuator: Mechanical Design Optimization According to Application
Actuators
New robotic applications, among others, in medical and related fields, have in recent years boosted research in the development of new actuators in the search for solutions that are lighter and more flexible than conventional actuators. Shape-Memory Alloy (SMA)-based actuators present characteristics that make them an excellent alternative in a wide variety of applications. This paper presents the design, tests (with the control description) and analysis of various configurations of actuators based on SMA wires: flexible SMA actuators, different mechanical design to multiply the displacement and different configurations for actuators with multiple SMA wires. The performance of the actuators has been analyzed using wires of different activation temperatures. The influence of the Bowden sheath of the flexible actuator has been tested, as has the thermal behavior of actuators with several wires. This work has allowed determination of the most effective configuration for the development...
Optimal design of shape memory alloy wire bundle actuators
2002
This research studied the optimal design of Shape Memory Alloy (SMA) muscle wire bundle actuators. Current literature describes the use of multiple muscle wires placed in parallel to increase the lifting capabilities of an SMA actuator, which however, is limited to wires of like-diameter. A constrained optimization problem was formulated, with constraints on the maximum number of wires, voltage applied, and SMA bundle length and cross-sectional area, that explored the use of several different diameter wires for the development of an optimal SMA bundle actuator that will be able to apply maximum force. As a case study, the optimal design of SMA bundle actuators for the Rutgers robotic hand is presented.
Shape Memory Alloys as Artificial Muscles
2021
In this technologically advanced time ‘lower back pain’ is one of the most problems in people. There is an extensive demand of research in this complex field of engineering. Thus, the spinal implant research plays a key role in solving the problems. This research focuses on analysing the characteristic and behaviour of spinal instruments without using animal and cadaveric models. The main focus of the research is to develop a simplified laboratory spine with artificial muscles and ligaments mimicking the behaviour and characteristic of lower back. The article targets shape memory wires that can be used as artificial muscles.
Shape Memory Alloy Actuators: A Review
International Journal for Research in Applied Science and Engineering Technology
The Shape memory alloys (SMAs) comes under special class of materials which possesses ability to recover their original shape at some temperatures characteristics. The SMAs are being used in different field in variety of applications. This ability of SMA can be viewed under high applied loads and elastic deformations. In this review paper, the SMA actuators and their applications are discussed. Keywords: SMA, Types of SMA, actuator. I. INTRODUCTION The term ''smart alloy'' was introduced in 1932 and the nomenclature ''shape-memory'' was given in 1941 for polymeric dental material [1, 2, 3]. Shape memory alloys (SMAs) are a unique type of material contains the ability to recover their shape at certain temperature characteristics. These materials are able to regain their original shape, even after reaching large inelastic deformations (near 10%) [1]. The demand for SMAs for engineering applications has been increasing in different fields; such as in industrial applications, automobile industries, aerospace applications, structures and composites, robotics and biomedical applications [4, 5]. Different SMA actuators like wire, compression / tension springs and cantilever had been used in thermal and electrical actuation systems [7, 33]. In this paper, a review on different applications of SMA actuators is presented.
Journal of Intelligent Material Systems and Structures, 2019
The present article investigates and explores the effect of partial phase transformation on the response of shape adaptive/morphing structures controlled by shape memory alloy wire actuators subject to variable trajectory and high actuation speed requirements, where the effect of partial transformation becomes more dominant. A modified constitutive model is adopted for the prediction of the thermo-mechanically coupled response on a trailing edge shape adaptive rib prototype intended for active load alleviation in large wind turbine blades, and the simulated behavior is subsequently correlated with experimental results. The experimentally validated model is further used to predict the response of the full-scale camber-line adaptive structure with shape memory alloy Ni 51 Ti 49 wt% actuators in antagonistic configurations, under demanding operational time target trajectories at extreme turbulence conditions. Comparison of the results, with a case that omits partial transformation behavior, reveals substantial improvements in the predicted target trajectories, actuation speed, actuator stresses, and required operational temperature variation. The latter discloses the enhanced potential of shape memory alloy actuators to provide higher transformation rate and possibly higher fatigue life combined with lower energy demands toward the design and realization of efficient morphing structures.
Characterization and design of antagonistic shape memory alloy actuators
Antagonistic shape memory actuators use opposing shape memory alloy (SMA) elements to create devices capable of producing differential motion paths and two-way mechanical work in a very efficient manner. There is no requirement for additional bias elements to 're-arm' the actuators and allow repetitive actuation. The work generation potential of antagonistic shape memory actuators is determined by specific SMA element characteristics and their assembly conditions. In this study, the selected SMA wires are assembled in antagonistic configuration and characterized using a dedicated test bench to evaluate their stress-strain characteristics as a function of the number of cycles. Using these functional characteristics, a so-called 'working envelope' is built to assist in the design of such an actuator. Finally, the test bench is used to simulate a real application of an antagonistic actuator (case study).
Volume 1: Multifunctional Materials; Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Structural Health Monitoring, 2016
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 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.
Development of a shape memory alloy wire actuator to operate a morphing wing
Journal of Theoretical and Applied Mechanics, 2014
DSC tests were performed on several types of SMAs to verify the phase-transformation temperatures, and then experiments to examine their characteristics were carried out. An electric-current was supplied to the SMA wire to measure the appropriate operational current range. The force generated by the SMA wire increased according to the supplied current, but it diminished when the over-current was supplied because thermo-mechanical properties of the wire started to degrade. The appropriate stress range for effective actuation characteristics was also investigated. The SMA wire actuator was designed to operate a morphing wing. Experiments for the wing were conducted to verify its characteristics and it was smoothly deformed.