Amadeusz Nowak

Hysteresis Modelling of a Piezoelectric Tube Actuator

The article concerns about a piezoelectric tube actuator hysteresis. The actuator can bend in two directions and application of this piezo elements can entail new features and capabilities of mechatronic devices. Unfortunately as other smart materials, piezoelectric materials are distinguished by hysteresis phenomenon. Authors present result of displacement measurement, which was performed for decreasing amplitude cosine input signal. Based on this result phenomenological generalized Prandtl-Ishlinskii model was matched. The results of the piezoelectric tube and the model displacement were compered.

Magnetic Shape Memory Alloys Modelling and Pneumatic Applications

Very generally material science could be divided into two groups: scientists who try to invent new materials or improve existing ones and those who work on finding the best applications for the modern materials. Among them there is group named “smart materials” or “active materials”, which have ability to change theirs properties according to the external stimulation. One of the relatively most recent smart material is magnetic shape memory alloy, MSMA in abbreviation. The authors of the article focus on testing samples of this material and try to adapt them to use in fluid devices. The paper mentions about some most interesting valves’ designs equipped with smart materials and summaries the previous MSMA research of the authors. It begins with literature overview of smart material applications in pneumatic or hydraulic valves. There is only one example of MSMA application in valve, therefore the overview concerns mainly the use of piezoelectric, thermal shape memory alloys and giant magnetostrictive materials. Next section describes general properties of the magnetic shape memory alloys and underlines the differences between more widely known Thermal Shape Memory Alloys and MSMA materials. One of the most important property is wide, nonsymmetrical hysteresis in static characteristics of the material, which can be seen as advantage or disadvantage, depending on the application. The material preserves its shape until perpendicular magnetic field or additional force appear. The authors mention about modeling MSMA hysteresis aspect. Three different hysteresis models were briefly described: Generalized Prandtl-Ischlinski, Preisach and Krasnoselskii-Pokrovskii. The last section treats about the current MSMA based valve design concept. It assumes usage of two identical pieces of MSMA materials and energize them oppositely. There is flapper mounted between MSMA samples, which displacement depends on the MSMA elongations. This actuator type is called “push-push” type. Lack of the return spring result in remaining of the flapper in its final position after decreasing of the supply current. The advantage of the solution could be lowering energy consumption of the valve, when the valve setting changes relatively rare during its work. In the future, the presented hysteresis models could improve the work of such MSMA based valve.

Pneumatic single flapper nozzle valve driven by piezoelectric tube

The article presents a construction, static testing and modelling of a single flapper nozzle pneumatic valve. Authors show testing of piezo tube PT230 which distinguishing feature is deflection in two directions. This testing is preliminary work in design of a novel electropneumatic valve. Studies have been performed on a special designed bench which consists of a pneumatic valve, which used piezo tube as a flapper. Data acquisition process and control were performed by dSPACE system. The preformed static pressure control tests, confirmed applicability of tube actuator in flapper nozzle type valves. Obtained results were compared with simulation model prepared in Matlab Simulink software. Streszczenie. Artykul zawiera opis konstrukcji, badania statyczne i modelowanie zaworu typu dysza przyslona. Autorzy zaprezentowali badania piezo rurki model PT230, ktorej cechą charakterystyczną jest mozliwośc odksztalcenia w dwoch kierunkach. Praca ta jest przygotowaniem do konstrukcji nowego zaworu elektropneumatycznego. Badania zostaly wykonane na specjalnie w tym celu wykonanym stanowisku zawierającym zawor, ktorym zastosowano piezo rurke jako przyslone. Procesy akwizycji danych oraz sterowania wykonane zostaly w systemie dSPACE. Przeprowadzone badania statyczne sterowania ciśnieniem wyjściowym, potwierdzają mozliwośc zastosowania piezo rurki w zaworach typu dysza przyslona. Zarejestrowane wyniki poddano porownaniu z modelem przygotowanym w oprogramowaniu Matlab Simulink. (Zawor pneumatyczny typu dysza przyslona z rurką piezoelektryczną jako elementem zadającym)

Multichannel High Voltage Amplifier for Piezo Actuators

This paper describes investigations of a low cost high voltage amplifier, which was based on specialized operational amplifiers. The purpose of the amplifier is to control piezoelectric actuators with many electrodes, such as bimorph benders, piezoelectric tubes, ring and disc benders. Proposed amplifier has two independent channels which can be configured for the specific research aim. Every channel of the device can works in inverted or non inverted mode. Also the voltage gain and current limit can be set separately.

Analysis Thrust for Different Kind of Propellers

The paper presents a design of test stand designed for thrust propellers measurements. There are shown results of the thrust for different propellers. The study thrust was made for six different propellers. Propellers differed in terms of diameter, pitch and material. For all of propellers used was the same drive and the same control parameters (voltage, current). During thrust measurements HBM force sensor was used. The propeller drive BLDC motor was used, which was controlled by a system of dSPACE. The following paper analyses indicates that propeller diameter is its most important parameter and in some range thrust is proportional to diameter.

Characteristics of the Improved Magnetic Shape Memory Alloy Actuator Test Stand

The article describes improved magnetic shape memory alloy actuator (MSMA actuator) test stand and the previously made stand. There are pointed weak sides of the first stand and the improvements in the new one. Several quasi-static measurements were performed and results were compared between both measurement stands. The MSMA actuator characterises with significant hysteresis loop, but improved test stand allowed to reduce its width. The increased rigidity of the stand excluded influence of stand deformations on the results. The described stand resulted with similar but improved measurements of the MSMA actuator characteristics, which also proved the correctness of the previous results.

Analysis and Modelling of Magnetic Circuits in Magnetic Shape Memory Alloy Actuators

Authors presented in article modeling of magnetic circuit for magnetic shape memory alloys. These alloys are a new class of smart materials which can generate strains and force in external magnetic field. Thus that properties MSMA fill gap between classical SMA and magnetostrictive materials. As a drawbacks strong nonlinearities should be mentioned: wide asymmetric hysteresis loop, thermal sensitivity, first cycle effect. Very high flux density need for effective operation over the whole range strongly affects on size of the magnetic circuit. Mathematical modeling does not allow for design optimal shape of core. Authors aided their work by FEA of magnetic flux in core. Computed results were compared with magnetic induction measured on prepared test bench.