Materials & Testing
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New developments in piezo actuators: Long stroke actuators and high power electronics
19 June 2023
In many cases piezoelectric actuators reach limitations in terms of maximum displacement and cycling frequency. Most amplified actuator technologies struggle to go over the millimeter of stroke. Furthermore certain closed-loop applications demand stroke measurement integrated into the actuator. While few amplifiers on the market can offer 20Amps current over a few 100ms, development of high power supply units runs parallel with actuator improvements. However with the introduction of high power supplies comes the problem of self-heating of the piezo ceramic. Finally extreme environmental conditions in terms of harsh conditions and high temperatures need to be addressed in order to open these markets for piezo actuators. Cedrat Technologies has been heavily investigating in solutions to overcome all of these drawbacks and these solutions are
presented here.
Piezo qualification for space applications
6 January 2002
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.
Piezo-composite patches applied to the detection of defects using lamb wave focusing
19 June 2023
Ultrasonic-based SHM (Structural Health Monitoring) applications usually rely on the use of piezo-electric patches to emit and receive ultrasonic surface acoustic waves. The principle is to study the propagation of the waves through a structure to assess its health. Because of the elevated number of echoes and possible modes of propagation of the acoustic waves within the structure, those applications suffer from a burden of signal processing. This paper presents a composite piezo-electric patch and its electronics that were designed and successfully tested for reducing the complexity of the SHM detection schemes.
Smart actuators for aircraft applications
4 January 2003
Smart actuators and intelligent structures receive a considerable interest in the fields of Air & Space, to realise new functions or more efficient functions than passive structures. In these fields, there are needs for actuation means offering high mechanical energy density (product of stroke and force divided by the mass), a low power consumption, a resistance to severe environment (such as vibrations) as well as other case by case needs : High resolution (embedded active optics for cameras and telescopes), fast response (active control of structures shape, active damping of vibration)…
ACTUATORS BASED ON GIANT MAGNETOSTRICTIVE MATERIALS
6 January 2002
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.
Advantages of large piezo actuators and high power drivers for fatigue and fretting test
19 June 2023
Constant expansion of new materials requires fretting or fatigue machines in order to test their failure. In many cases tests must be performed in severe conditions and at high frequency. These requirements come from the use of the materials in highly demanding applications. At the same time it is expected to reduce the time required to characterise such materials. Piezoelectric actuators are more and more common in testing machines, but they still reach limitations in terms of maximum displacement, cycling frequency or power. In order to cope with these issues, Cedrat Technologies has been investigating solutions. In this paper long stroke and high frequency actuators, coupled with powerful driving control are introduced. These actuators are based on piezoelectric materials and can be easily integrated into the fatigue machines. In order to improve precision of these tests, two of the most common displacement sensors used in smart actuators are also presented in this paper.