The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Performance and Modeling of Magnetic Shape Memory Actuators and Sensors

Ilkka Suorsa

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 16th of May, 2005, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7645-3)   [639 KB]
Dissertation is also available in print (ISBN 951-22-7644-5)

Abstract

Magnetic Shape Memory (MSM) materials comprise a new active material type, which can change its shape in magnetic fields. Non-stoichiometric Ni-Mn-Ga in 5M martensite is the most utilized MSM material so far. It has been used also in this study. The material has also a reverse effect: the change in shape of the material with non-zero magnetization alters the magnetic field in which it is placed. Due to its properties, the material has two promising applications: motion-generating actuators and sensors. In this work, both sensors and actuators are studied with interest focused on the modeling and operation parameters of the applications. A lumped parameter model for contruction of an actuator and a sensor consisting of models for MSM effect and magnetic, mechanical and electric circuits of the application has been made. The models have been tested with measurements.

In addition, the properties of the material itself have been studied. The magnetic field induced stress and the magnetization dependence on strain have been measured. The magnetic field induced stress in MSM material was found to be in accordance with existing theory. Under high magnetic fields, the measured magnetization dependence on strain was also predicted by the existing theory. However, a new functional dependence was found under low magnetic fields. New MSM applications have been built and tested as linear motors and speed sensors. The speed sensor can also be used as a voltage generator. Associated with the linear motor, a control system for MSM actuators was studied and built.

This thesis consists of an overview and of the following 6 publications:

  1. Suorsa I. and Pagounis E., 2004. Magnetic field-induced stress in the Ni-Mn-Ga magnetic shape memory alloy. Journal of Applied Physics, Vol. 95, No. 9, pp. 4958-4961. © 2004 American Institute of Physics. By permission.
  2. Suorsa I., Pagounis E. and Ullakko K., 2004. Magnetization dependence on strain in the Ni-Mn-Ga magnetic shape memory material. Applied Physics Letters, Vol. 84, No. 23, pp. 4658-4660. © 2004 American Institute of Physics. By permission.
  3. Suorsa I., Tellinen J., Ullakko K. and Pagounis E., 2004. Voltage generation induced by mechanical straining in magnetic shape memory materials. Journal of Applied Physics, Vol. 95, No. 12, pp. 8054-8058. © 2004 American Institute of Physics. By permission.
  4. Suorsa I., Pagounis E. and Ullakko K., 2004. Magnetic shape memory actuator performance. Journal of Magnetism and Magnetic Materials, Vol. 272-276, pp. 2029-2030. © 2004 Elsevier Science. By permission.
  5. Suorsa I., Tellinen J., Pagounis E., Aaltio I. and Ullakko K., 2002. Applications of magnetic shape memory actuators. Proceedings of the Actuator 2002 Conference. Bremen, Germany, 12-14 June 2002, pp. 158-161.
  6. Suorsa I., Tellinen J., Aaltio I., Pagounis E. and Ullakko K., 2004. Design of active element for MSM actuator. Proceedings of the Actuator 2004 Conference. Bremen, Germany, 14-16 June 2004, pp. 573-576.

Keywords: magnetic shape memory material, Ni-Mn-Ga, sensors, actuators, magnetic modeling

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© 2005 Helsinki University of Technology

Last update 2011-05-26