International Journal of Applied Electromagnetics and Mechanics - Volume 12, issue 1-2

Authors: Kohl, M. | Göbes, J. | Krevet, B.

Article Type: Research Article

Abstract: A new type of normally-closed gas microvalve is presented. The valve makes use of two micromachined SMA thin sheet devices, an active SMA device displaying the one-way shape memory effect and a passive superelastic SMA device, which maintains a normally-closed position. The outer diameter and height of the valve are 6 mm. Gas flow experiments in stationary equilibrium reveal a maximum flow of 470 standard ccm (sccm) at a pressure difference of 8000 hPa and a …power consumption of 260 mW. The dynamics of heat transfer to and from the active microdevice is investigated by infrared microscopy and coupled FEM simulations. At 300 mW heating power, the heating time is about 1.2 s. Typical cooling times vary between 1.8 and 5 s depending on the gas flow. Show more

DOI: 10.3233/JAE-2000-200

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 12, no. 1-2, pp. 71-77, 2000

Authors: Tanaka, M. | Goto, H. | Namima, T. | Matsuki, H. | Orikasa, S. | Tanahashi, Y. | Chonan, S.

Article Type: Research Article

Abstract: This paper is concerned with the development of an artificial urethral valve for treating urinary incontinence, which is driven by shape memory alloy actuators. The latest valve has been modified by adding the SMA for the closing, which has the effect of preventing incorrect actions. Further, a compact, non-contact induction heating system using power transmission coils is introduced, which is improved by using an oscillation and amplifier circuit. It is found that the valve shows good …opening and closing functions experimentally by using the urethrae of male dog through the induction-heating system. Show more

DOI: 10.3233/JAE-2000-195

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 12, no. 1-2, pp. 79-85, 2000

Authors: Qiu, Jinhao | Tani, Junji | Osanai, Daisuke | Urushiyama, Yuta | Lewinnek, David

Article Type: Research Article

Abstract: The main problem with Shape Memory Alloy (SMA) actuators is their slow response speed. Current SMA actuators work in tens of seconds though they can generate large force and displacement outputs. The objective of the research in this paper is to improve the response speed of SMA actuators to 10 milliseconds or less. SMA actuators are driven by thermal energy and their slow response is attributed to the inefficient heat transfer. To improve the response, direct …Ohmic heating was used in the experiments. The SMA actuators used in this study are Ti-Ni-Cu columns of \phi 5\times 50 mm with residual strain produced upon unloading after 5.3% displacement response of the SMA actuators without axial constraint and the transient force response of the actuators under axial constraint were measured with direct heating. The shortest response time achieved for unconstrained actuators is 4.6 ms and that for constrained actuators is 6.5 ms. The average value of maximum recovery force is 10.8 kN, which corresponds to 550 MPa of recovery stress. It was also found that constrained actuators need about 50% more energy for heating than unconstrained actuators. Show more

DOI: 10.3233/JAE-2000-199

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 12, no. 1-2, pp. 87-100, 2000

Authors: Takashina, Kentaro | Yabe, Hiromasa | Oguri, Kazuya | Miyazawa, Yasuyuki | Nishi, Yoshitake

Article Type: Research Article

Abstract: In order to evaluate the adaptability for supporting material for micro-actuator, mechanical properties (P_c^{\rm mid},\ d_c^{\rm mid} and E_c^{\rm mid} ) were measured by means of Vickers indentation method. The high ductility and high stiffness were observed for the slowly cooled glass sample. In addition, the high deformability was confirmed for the slowly cooling sample above the glass transition temperature. Since the shape memory metallic bi-glass can be applicable to micro-actuator …under irradiated conditions, a bimetal constructed by the Zr_{55} Al_{9} Ni_5 Cu_{31} glassy alloy and molybdenum-supporting sheet were also studied. The large shape change was observed near glass transition temperature. Show more

DOI: 10.3233/JAE-2000-191

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 12, no. 1-2, pp. 101-105, 2000

Authors: Hagiwara, Naotada | Yabe, Hiromasa | Oguri, Kazuya | Asaka, Takashi | Suzuki, Tsunenori | Nishi, Yoshitake

Article Type: Research Article

Abstract: In order to obtain strong power of shape memory effects for application as an actuator, the volume change on softening of the high T_c YBa_2 Cu_3 O_{6.9} superconductor was studied. A softening induced volume change was found from 90 K to 160 K.

DOI: 10.3233/JAE-2000-193

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 12, no. 1-2, pp. 107-110, 2000