Shape Memory Alloy Based Rotational Actuator

2018 ◽  
Author(s):  
Nick Hofmann ◽  
Michael P. Hennessey
Keyword(s):  
Shape Memory ◽  
Rotational Motion ◽  
Thermal Analyses ◽  
Peak Torque ◽  
Advanced Materials ◽  
Constant Torque ◽  
Heating And Cooling ◽  
Air Convection ◽  
Technological Developments ◽  
Forced Air

Due to recent technological developments in advanced materials, the integration of shape memory alloys (SMAs) into new machines and mechanisms is becoming more common and it offers tremendous potential for the future. Using currently available properties of common SMA materials, the paper’s contribution is to: Study through dynamic simulation the potential offered by SMA springs to serve as the basis for rotary actuation. In the process, the SMA displaces a rocker arm rotating about an axis to induce rotational motion of a driveshaft, in effect converting a force into rotational motion. When embedded in a cycle with heating & cooling phases and a resetting mechanism, unidirectional rotational motion can be achieved. Regarding heating and cooling cycles, forced air convection is used to reduce thermal cycle cooling and is calculated via transient thermal analyses. Using typical parameter values for the representative design considered, through forced air convection, cooling cycles are reduced from approximately 30 seconds (natural) to 5.5 seconds (forced) and as a result, a complete system cycle can occur in 10 seconds, with the applied inertial load of 2.0 kg-m2. Using MATLAB and Simulink, a nonlinear 3rd order dynamic system model was created and simulations were performed. One complicating factor concerned angular limits and the necessary thermal cycling, which was solved through appropriate sequencing and resetting of integrators for different phases. Simulation results for the design considered show that a peak torque of 1.72 N-m is possible and that relatively smooth motion and approximately constant torque output is also possible through the addition of a few more rocker arm systems, properly commutated. Lastly, the design analysis framework and results may inspire future realization of actual devices.

Design and experimental analysis of a smart bearing using shape memory alloy springs

2020 ◽  
Vol 31 (11) ◽  
pp. 1390-1402
Author(s):  
Andersson Guimarães Oliveira ◽  
Antônio Almeida Silva ◽  
Carlos Jose de Araújo ◽  
Richard Senko ◽  
Rômulo Pierre B dos Reis
Keyword(s):  
Shape Memory Alloy ◽  
Response Time ◽  
Shape Memory ◽  
Natural Frequency ◽  
Rotating Machinery ◽  
Joule Effect ◽  
Helical Springs ◽  
Air Convection ◽  
Forced Air ◽  
Level Reduction

Among many rotating machinery vibration sources, there is one due to resonance, when the machine operation frequency crosses the natural frequency region. This study proposes a smart bearing that employs shape memory alloy NiTi helical springs for vibration-level reduction. This smart bearing is capable of dynamically changing its stiffness during machine acceleration or deceleration, keeping its natural frequency far from resonance. Activated by Joule effect and cooled by forced air convection, the prototype installed in horizontal rotating machinery reaches reduction of vibration amplitude of about 63% (root mean square) and 73% (Peak) at critical speed, with response time between 12–15 s. Compared with the results of the reference articles, satisfactory amplitude reduction and better response time were observed.

scholarly journals Toward Low-Cost Highly Portable Tactile Displays with Shape Memory Alloys

2007 ◽  
Vol 4 (2) ◽  
pp. 57-70 ◽  
Author(s):  
R. Velázquez ◽  
E. E. Pissaloux ◽  
M. Hafez ◽  
J. Szewczyk
Keyword(s):  
Shape Memory ◽  
Active Element ◽  
Low Cost ◽  
Tactile Display ◽  
Helical Springs ◽  
Niti Sma ◽  
Air Convection ◽  
Tactile Displays ◽  
Forced Air ◽  
Visually Disabled

This paper presents a new concept of low-cost, high-resolution, lightweight, compact and highly portable tactile display. The prototype consists of an array of 8 × 8 upward/downward independent moveable pins based on shape memory alloy (SMA) technology. Each tactile actuator consists of an antagonist arranged pair of miniature NiTi SMA helical springs capable of developing a 300 mN pull force at 1.5 Hz bandwidth by using simple forced-air convection. The proposed concept allows the development of 200 g weight tactile instruments of compact dimensions which can be easily carried by a visually disabled user. A detailed technical description of the SMA active element, tactile actuator and tactile display is presented and discussed. Preliminary perceptual results confirm the effectiveness of the display on information transmission.

Natural and forced air convection operation in a direct solar dryer assisted by photovoltaic module for drying of green onion

Solar Energy ◽  
2021 ◽  
Vol 220 ◽  
pp. 24-34
Author(s):  
Letícia Ferraresi Hidalgo ◽  
Mariana Nascimento Candido ◽  
Karina Nishioka ◽  
José Teixeira Freire ◽  
Gustavo Nakamura Alves Vieira
Keyword(s):  
Photovoltaic Module ◽  
Air Convection ◽  
Solar Dryer ◽  
Forced Air

scholarly journals Laboratory-Scale Processing and Performance Assessment of Ti–Ta High-Temperature Shape Memory Spring Actuators

2021 ◽  
Author(s):  
A. Paulsen ◽  
H. Dumlu ◽  
D. Piorunek ◽  
D. Langenkämper ◽  
J. Frenzel ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Detrimental Effect ◽  
Wire Drawing ◽  
Fast Heating ◽  
Heating And Cooling ◽  
Arc Melting ◽  
Ω Phase ◽  
And Performance

AbstractTi75Ta25 high-temperature shape memory alloys exhibit a number of features which make it difficult to use them as spring actuators. These include the high melting point of Ta (close to 3000 °C), the affinity of Ti to oxygen which leads to the formation of brittle α-case layers and the tendency to precipitate the ω-phase, which suppresses the martensitic transformation. The present work represents a case study which shows how one can overcome these issues and manufacture high quality Ti75Ta25 tensile spring actuators. The work focusses on processing (arc melting, arc welding, wire drawing, surface treatments and actuator spring geometry setting) and on cyclic actuator testing. It is shown how one can minimize the detrimental effect of ω-phase formation and ensure stable high-temperature actuation by fast heating and cooling and by intermediate rejuvenation anneals. The results are discussed on the basis of fundamental Ti–Ta metallurgy and in the light of Ni–Ti spring actuator performance.

Experimental Validation and Numerical Simulation of Shape Memory Flat Wire Actuators

2014 ◽  
Author(s):  
Alexander Czechowicz ◽  
Sven Langbein
Keyword(s):  
Shape Memory Alloy ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Smart Materials ◽  
Empirical Data ◽  
Dynamic Properties ◽  
Fatigue Behavior ◽  
Different Boundary Conditions ◽  
Heating And Cooling ◽  
Actual Shape

Shape memory alloys (SMA) are thermally activated smart materials. Due to their ability to change into a previously imprinted actual shape through the means of thermal activation, they are suitable as actuators for mechatronical systems. Despite of the advantages shape memory alloy actuators provide, these elements are only seldom integrated by engineers into mechatronical systems. Reasons are the complex characteristics, especially at different boundary conditions and the missing simulation- and design tools. Also the lack of knowledge and empirical data are a reason why development projects with shape memory actuators often lead to failures. This paper deals with the dynamic properties of SMA-actuators (Shape Memory Alloy) — characterized by their rate of heating and cooling procedures — that today can only be described insufficiently for different boundary conditions. Based on an analysis of energy fluxes into and out of the actuator, a numerical model of flat-wire used in a bow-like structure, implemented in MATLAB/SIMULINK, is presented. Different actuation parameters, depending on the actuator-geometry and temperature are considered in the simulation in real time. Additionally this publication sums up the needed empirical data (e.g. fatigue behavior) in order to validate the numerical two dimensional model and presents empirical data on SMA flat wire material.

scholarly journals Expansion of renewable energy resources and energyconscious behaviour at the University of Szeged

2018 ◽  
Vol 48 ◽  
pp. 03006 ◽  
Author(s):  
László Gyarmati
Keyword(s):  
Renewable Energy ◽  
Energy Use ◽  
Energy Resources ◽  
Solar Panels ◽  
Renewable Energy Resources ◽  
Investment Planning ◽  
Heating And Cooling ◽  
Natural Energy ◽  
Technological Developments ◽  
The University

At the University of Szeged, as the greenest University of Hungary, the sustainability project is built on two pillars. One of them is based on events and communication campaigns held regularly for the University citizens to prompt environmental-conscious behaviour, whereas the other is built on technological developments and on the extensive use of renewable energy resources. Thus the development of built environment and social responsibility both support the adequacy to sustainability requirements. The spreading of the effective solutions to making more and more buildings of the University energy efficient, numerous investments using renewable energy are also responsible for the decrease of the natural energy use of the institution contrary to the fact that the number of the buildings of the University of Szeged is continually increasing. It can be stated that the University of Szeged is committed to using renewable energy which is taken into consideration of each investment planning. The following examples confirm it: using geothermal cascade system for heating and cooling of five university bulidings, solar panels on 24 builidings and a unique technology of using the heat of wastewater to cool and heat one of the main bulidings of the university, namely the Study and Information Centre.

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