Magnetic field induced strain materials are classically represented by Giant Magnetostrictive Materials (GMM) such as Tb-Dy-Fe alloys offering magnetostrain of 0.1-0.2%. This family of smart materials has been extended for some years by cryogenic magnetostrictive materials such as Td-Dy and (Tb1-xDyx)Zn offering magnetostrain of 0.2- 1%. Even more recently, it has been completed by new Magnetic Shape Memory Materials (MSM) such as Ni-MnGa offering magnetostrain of 2-6%. These materials have lead to quite various large stroke and large force actuators. Some of these actuators meet the requirements of applications in different fields such as space or machine tools. The object of this paper is to review the present situation and recent progresses in the field of magnetic field induced strain materials, actuators, modelling and applications, including commercial aspects.
Piezoelectric actuators are generally deemed good candidates for driving compact and efficient mechanisms, offering advantages like fine precision, fast time response, low power consumption, cost annd easier implementation. But to meet space, devices have to comply to many other requirements besides functional ones.
Amplified Piezo Actuators have been developed at CEDRAT TECHNOLOGIES for several years. Their well – known advantages (rapid response and precise positioning) have been used in valve designs to obtain both rapid or fine proportional valves.
During the past thirty years, noticeable consideration has been devoted to the improvement of rotary-wing vehicles, with respect to noise, vibrations and performance. The main rotor of helicopters, and more precisely the blades themselves have been the subject of numerous optimization studies.
The applications of piezoelectric actuators are spreading in various fields such as precise micro-positioning, shape control or vibration generation, control or damping.
Implementation of 3D capabilities on ultrasonic imaging systems tantalizingly proves the high interest for this diagnosing modality. However, to become a clinical tool, 3D ultrasound has to spend further technological efforts in acquisition performance and probe size to deliver on the fly, quality volumetric images as well as current functionalities.
Existing piezo motors such as travelling wave motors present several technical limitations, they are not useable for linear drive, they cannot be easily adapted to specific rotational needs and the development of customised solution is expensive. The proposed Ultrasonic Piezo Drive (UPD) aims at overcoming these limitations. It is a shell-based stator using multilayered piezoceramics in d33 mode. Excited at only 1-10V, it produces an ultrasonic elliptical vibration large enough to direct drive any type of second body by friction. Tangential driving properties of UPD20 are typically in the range of 100-200mm/s max speed and 15-30N max force.
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