Modelling and Validation of a Rotary Motor Combining Shape Memory Wires and Overrunning Clutches

2014 ◽  
Author(s):  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Electrical Activation ◽  
Constant Force ◽  
Experimental Characterization ◽  
Low Friction ◽  
The Wire ◽  
Rotary Motor ◽  
Static Simulation

The paper presents the conceptual design, modeling and prototyping of a novel rotary motor based on shape memory alloy (SMA) wires. The basic architecture of the device capitalizes on a SMA wire wound around a low-friction cylindrical drum. The backup force to the SMA wire is provided by a beam spring which generates a nearly-constant force tangential to the drum. The electrical activation of the wire produces a contraction of the wire, hence a rotation of the drum fitted to the shaft through an overrunning clutch (free wheel). Thanks to the overrunning clutch, during the backup phase (recoiling of the wire), the drum rotates backward while the shaft does not move. Spurious backward movements of the shaft are contrasted by a second overrunning clutch linking the shaft to the frame. The paper presents a model for the quasi-static simulation of the motor and the experimental characterization of a prototype device featuring three active drums, a rotary sensor and an angular brake to apply the external load.

Design and Characterization of a Continuous Rotary Minimotor Based on Shape-Memory Wires and Overrunning Clutches1

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Low Friction ◽  
Maximum Torque ◽  
Output Torque ◽  
Large Rotations ◽  
Rotary Motor ◽  
High Output ◽  
Unidirectional Motion

An attractive but little explored field of application of the shape-memory technology is the area of rotary actuators, in particular for generating endless motion. This paper presents a miniature rotary motor based on shape-memory alloy (SMA) wires and overrunning clutches, which produces high output torque and unlimited rotation. The concept features an SMA wire tightly wound around a low-friction cylindrical drum to convert wire strains into large rotations within a compact package. The seesaw motion of the drum ensuing from repeated contraction–elongation cycles of the wire is converted into unidirectional motion of the output shaft by an overrunning clutch fitted between drum and shaft. Following a design process developed in a former paper, a six-stage prototype with size envelope of 48 × 22 × 30 mm is built and tested. Diverse supply strategies are implemented to optimize either the output torque or the speed regularity of the motor with the following results: maximum torque = 20 Nmm; specific torque = 6.31 × 10−4 Nmm/mm3; rotation per module = 15 deg/cycle; and free continuous speed = 4.4 rpm.

Design and Characterization of a Continuous Rotary Minimotor Based on Shape Memory Wires and Overrunning Clutches

2015 ◽  
Author(s):  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory ◽  
Design Process ◽  
Low Friction ◽  
Maximum Torque ◽  
Output Torque ◽  
Large Rotations ◽  
Rotary Motor ◽  
High Output ◽  
Unidirectional Motion

An attractive but little explored field of application of the shape memory technology is the area of rotary actuators, in particular for generating endless motion. This paper presents a miniature rotary motor based on SMA wires and overrunning clutches which produces high output torque and unlimited rotation. The concept features a SMA wire tightly wound around a low-friction cylindrical drum to convert wire strains into large rotations within a compact package. The seesaw motion of the drum ensuing from repeated contraction-elongation cycles of the wire is converted into unidirectional motion of the output shaft by an overrunning clutch fitted between drum and shaft. Following a design process developed in a former paper, a six-stage prototype with size envelope of 48×22×30 mm is built and tested. Diverse supply strategy are implemented to optimize either the output torque or the speed regularity of the motor with the following results: maximum torque = 20 Nmm; specific torque = 6.31×10−4 Nmm/mm3; rotation per module = 15 deg; free continuous speed = 4 rpm.

Experimental Characterization of a Shape Memory Alloy-Based Morphing Radiator

2016 ◽  
Author(s):  
Christopher L. Bertagne ◽  
Jorge Chong ◽  
Darren J. Hartl ◽  
John D. Whitcomb ◽  
Lisa R. Erickson ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Experimental Characterization

Analytical Modelling of Rolamite Mechanism Made of Shape Memory Alloy for Constant Force Actuators

2015 ◽  
Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Metal Strip ◽  
Force Generation ◽  
Constant Force ◽  
Low Friction ◽  
Actuation Force ◽  
Long Stroke ◽  
Force Generator ◽  
Roll Back

This paper analyses the Rolamite architecture exploiting shape memory alloys as power element to obtain a solid state actuator. The Rolamite mechanism was discovered in the late sixties, initially as precision and low friction linear bearing. The most common Rolamite configuration consists of a flexible thin metal strip and two rollers mounted between two fixed parallel guide surfaces. The system can roll back and forth without slipping guided by the plates along its so called sensing axis. The system presents another relevant advantage in addition to low friction coefficient, which is the possibility to provide force generation in a quite simple way. In the original literature works the force was provided thanks to cutouts of various shape in the strip, though this method does not allow the Rolamite to be considered a proper actuator, but only a force generator. In this paper we developed the idea of exploiting the shape memory alloy as Rolamite power element and therefore to use the shape memory effect to change the elastic properties of the strip and to provide the actuation force. The mechanical analyses and the equations where the martensite-austenite transition is modelled in a simplified way, show that this application is feasible, mainly thanks to the initial precurvature of the SMA strip. The discussion of the results highlights some important merits of this architecture such as long stroke, constant force and compactness.

Analytical modelling of Rolamite mechanism made of shape-memory alloy for constant force actuators

2016 ◽  
Vol 28 (16) ◽  
pp. 2208-2221 ◽  
Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Analysis ◽  
Metal Strip ◽  
Constant Force ◽  
Low Friction ◽  
Actuation Force ◽  
Long Stroke ◽  
Force Generator ◽  
Roll Back

This article analyses the Rolamite architecture exploiting shape-memory alloys as power element to obtain a solid-state actuator. The Rolamite mechanism was discovered in the late 1960s, initially as precision and low friction linear bearing. The most common Rolamite configuration consists of a flexible thin metal strip and two rollers mounted between two fixed parallel guide surfaces. The system can roll back and forth without slipping guided by the plates along its so-called sensing axis. The system presents another relevant advantage in addition to low friction coefficient, which is the possibility to provide force generation in a quite simple way. In the original literature works, the force was provided, thanks to cut-outs of various shapes in the strip, although this method does not allow the Rolamite to be considered a proper actuator, but only a force generator. In this article, we developed the idea of exploiting the shape-memory alloy as Rolamite power element, and therefore, to use the shape-memory effect to change the elastic properties of the strip and to provide the actuation force. The mechanical analysis, where the martensite–austenite transition is modelled in a simplified way, shows that this application is feasible, mainly thanks to the initial precurvature of the shape-memory alloy strip. The discussion of the results highlights some important merits of this architecture such as long stroke, constant force and compactness.

EXPERIMENTAL CHARACTERIZATION OF LINEAR SHAPE MEMORY ALLOY ACTUATORS

2019 ◽  
Author(s):  
Adriel Morgado de Moraes ◽  
Luciana Loureiro da Silva Monteiro ◽  
Ricardo Alexandre Amar de Aguiar
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Experimental Characterization ◽  
Linear Shape
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