Computer-Aided Development and Simulation Tools for Shape-Memory Actuators

2011 ◽  
Vol 43 (8) ◽  
pp. 2882-2890 ◽  
Author(s):  
Horst Meier ◽  
Alexander Czechowicz
Author(s):  
Sven Langbein ◽  
Alexander Czechowicz

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. Therefore, a need of developing methods, standardized testing of empirical properties and computer aided simulation tools is motivated. While computer-aided approaches have been discussed in further papers, as well as standardization potentials of SMA actuators, this paper focuses on a developing method for SMA actuators. The main part of the publication presents the logical steps which have to be passed, in order to develop an SMA actuator, considering several options like mechanical, thermal, and electrical options. As a result of the research work, the paper proves this method by one example in the field of SMA-valve technology.


Author(s):  
Horst Meier ◽  
Alexander Czechowicz

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 (lightweight-actuators, lower costs…etc.) these elements are only seldom integrated by engineers into mechatronical systems. The reason for this phenomenon is the insufficiently described dynamic behavior, especially at different boundary conditions. Also the lack of empirical data (like fatigue behavior and thermal balances) is a reason why development projects with shape memory actuators lead often to failures. Therefore a need of developing methods, standardized testings of empirical properties and computer aided actuator development systems is motivated. Based on an analysis of energy fluxes into and out of the actuator, a numerical model, implemented in MATLAB/SIMULINK is presented. The numerical model includes also a configuration and design tool which allows simulating different solutions to a problem. Additionally, this paper describes a development method for SMA which is fitted to uniqueness of these smart materials. In conclusion, this paper compares the conventional developing process to the presented method applying a mechatronical SMA-device.


2012 ◽  
Vol 23 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Sven Langbein ◽  
Alexander Czechowicz

Shape memory alloys (SMAs) have essential advantages compared with conventional actuators, in particular their high-power density and their silent mode of operation. However, this material has not yet gained acceptance in technical applications. The main reasons are the missing simulation tools and a lack of knowledge of materials as well as the companies’ uncertainty as to how to handle SMA. The resetting of the SMA element to generate a repeatable movement is often a defined problem. In this context, reset springs made of steel are conventional solutions, although their characteristics are a disadvantage. To reach a high level of power output and hence a high degree of efficiency, a reduction of the preload is necessary. A solution for this problem is an adaptive resetting. One main possibility to generate an adaptive resetting is given by the agonist–antagonist principle where two SMA elements work against each other. Here, the reset force can be applied if necessary. The advantage of this type of design is that a conventional return spring or a mechanical brake for clamping the position (electrically operated) is not necessary. Another possibility for adaptive resetting is to change the spring characteristics of a pseudoelastic SMA element by heating. The aim of this publication is to sum up the different possibilities of adaptive resetting of shape memory actuators. It also provides methods and the knowledge to support the development process of such resetting principles. The development of these methods is based on the analysis of different designs and requirements. Based on the experimental results, a conclusion of the possibilities is given.


2003 ◽  
Vol 112 ◽  
pp. 1181-1184 ◽  
Author(s):  
I. Vahhi ◽  
S. Pulnev ◽  
A. Priadko

1993 ◽  
Author(s):  
Robert W. Lashlee ◽  
Rajendra R. Damle ◽  
Vittal S. Rao ◽  
Frank J. Kern

2014 ◽  
Vol 07 (05) ◽  
pp. 1450063 ◽  
Author(s):  
Riccardo Casati ◽  
Carlo Alberto Biffi ◽  
Maurizio Vedani ◽  
Ausonio Tuissi

In this research, the high performance shape memory effect (HP-SME) is experimented on a shape memory NiTi wire, with austenite finish temperature higher than room temperature. The HP-SME consists in the thermal cycling of stress induced martensite and it allows achieving mechanical work higher than that produced by conventional shape memory actuators based on the heating/cooling of detwinned martensite. The Nitinol wire was able to recover about 5.5% of deformation under a stress of 600 MPa and to withstand about 5000 cycles before failure. HP-SME path increased the operating temperature of the shape memory actuator wire. Functioning temperatures higher than 100°C was reached.


Author(s):  
Andrea Spaggiari ◽  
Igor Spinella ◽  
Eugenio Dragoni

The paper presents the design equations for an on-off shape memory alloy actuator under an arbitrary system of external constant forces. A binary SMA actuator is considered where a cursor is moved against both conservative and dissipative force which may be different during the push or pull phase. Three cases are analyzed and differentiated in the way the bias force is applied to the primary SMA spring, using a constant force, a traditional spring, or a second SMA spring. Closed-form dimensionless design equations are developed, which form the basis of a step-by-step procedure for an optimal design of the whole actuator.


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