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EN
In the paper the investigations performed at the Division of Mechtronic Devices at Poznan University of Technology in the area of application of both: smart materials in electro-hydraulic and electro-pneumatic valves, and new methods to control of hydraulic servo drives, are presented. In a first part the piezo bender actuator is shortly described and its application in servo valve is proposed. This actuator replaced the torque motor in the available on the market servo valve. The new valve simulation model is proposed. The simulation and investigations results of the servo valve with the piezo bending actuator are included. In the next part of the paper the application of piezo tube actuator in flapper-nozzle pneumatic valve is described. The test stand and investigations results are presented. Later, in the article, the Model Following Control (MFC) and Fractional order Control (FoC) methods are described. Their application in control of electrohydraulic servo drive is proposed. Some investigations results are included in the paper, showing the advantages of those control methods.
EN
One of the directions of modern development in the field of material research is the inclusion of features, enabling them to detect external stimuli and change their own properties in order to adapt to changes in the environment. Such materials evoke a new design philosophy that combines the actions of sensors, executive mechanisms, and control functions in one structure, which are capable of changing their response, depending on changes detected in the environment. In the article, the authors confront the expectations of theoretical solutions with the practical possibilities of modern technologies for the creation of intelligent engineering materials.
PL
Jednym z kierunków współczesnego rozwoju w dziedzinie badań materiałowych jest włączenie cech, umożliwiając im detekcję bodźców zewnętrznych i zmianę ich własnych właściwości w celu dostosowania się do zmian w środowisku. Takie materiały wywołują nową filozofię ich projektowania, która łączy działania sensorów, mechanizmów wykonawczych i funkcji sterujących w jednej strukturze, zdolnej do zmiany swojej reakcji w zależności od zmian wykrywanych w otoczeniu. W artykule autorzy konfrontują oczekiwania teoretycznych rozwiązań z praktycznymi możliwościami współczesnych technologii tworzenia inżynierskich materiałów inteligentnych. Dodatkową zaletą referatu są liczne przykłady nowych osiągnięć na świecie w tej dziedzinie z odniesieniami do współczesnej literatury naukowej.
EN
In rotating machinery, unattenuated excessive torsional vibration leads to damage and excessive wear. This type of vibration, which is transferred from one structure to another can be estimated using torsional transmissibility factor (TTF). The value of the TTF describes the ratio of output to input and reaches its peak at the natural frequency. Hence, the ability to vary coupling stiffness of two rotating shafts will allow the control of the TTF towards better performance and preventions from fatigue loading. Traditionally, passive rubbers are used as a flexible coupling in between two shafts. However, the constant passive stiffness of the material limits its performance. To address this issue, an adaptive coupling based on magnetorheological elastomer (MRE) is proposed to achieve better TTF at varying frequencies. Mathematical modelling, simulation study and experimental results of MRE for torsional vibration isolation are presented in this work. Natural frequency obtained from the TTF shows an increase of about 3 Hz when current changed from 1 to 6 A.
4
Content available remote Przegląd rozwiązań aktywnej kontroli drgań dla narzędzi skrawających
PL
W artykule przedstawiono problematykę drgań występujących w trakcie obróbki skrawaniem, negatywne konsekwencje, jakie za sobą niosą, a także to, w jaki sposób wpływają na proces obróbki skrawaniem. Omówiono również nowoczesne materiały wykorzystywane w aplikacjach tłumiących drgania, niemniej jednak zasadniczą część publikacji stanowi przegląd opublikowanych rozwiązań konstrukcyjnych wspomagających walkę ze zjawiskiem drgań towarzyszącym procesowi skrawania.
EN
The paper presents the issue of vibrations during the machining process, negative consequences caused by them and how they influence the machining process. Moreover, smart materials used in vibration damping have been discussed. The main part of the paper describes a review of published solutions which support the fight with the vibration phenomenon during machining.
EN
We have been accustomed to traditional materials such as wood, leather, wool... and have known the revolution of plastics and composites materials. Recently, we have known other innovations: these of smart materials able to change the shape as the piezoelectric materials. This work deals with the electro-mechanical modeling of these structures by the finite element method. It consists on to model and to simulate deformations in a square aluminum plate subjected to an electric field. This is achieved by using PZT piezoelectric transducers that have such particularity to deform under the influence of an electric field. The study of the deformed aluminum plates equipped with a PZT patch is considered and these types of materials are commonly used in aeronautics and astronautics, which is the context of our study. We have clearly shown the effect of the electromechanical properties of different piezoelectric materials, the transverse piezoelectric coefficient d31 and the longitudinal piezoelectric coefficient d33 of PZT patch on the final response of the intelligent structure.
EN
The following article is devoted to research on particular operational characteristics of prototypes of rotating magnetorheological clutches and brakes. The experiments were conducted on a specialized test stand, including a high power servo-motor, torque meters, and thermal sensors. In addition to the generally determined relationship of the clutch or brake torque transmitted over time and depending on the electric current, it has been shown that the particular operational characteristics of these devices are necessary for the full operational picture of the performance of the device. These are, among others, the torque versus rotational speed, temperature, and operational time dependencies.
PL
Praca poświęcona jest badaniom prototypów sprzęgieł i hamulców magnetoreologicznych pracujących w ruchu obrotowym. Zostały one przeprowadzone na specjalistycznym stanowisku badawczym. Obok powszechnie wyznaczanych zależności przenoszonego momentu obrotowego sprzęgła lub hamulca w funkcji czasu i w zależności od wartości natężenia prądu płynącego w solenoidach tych urządzeń i sterującego natężeniem pola magnetycznego wytwarzanego wokół cieczy magnetoreologicznej wykazano, że do pełnego obrazu eksploatacyjnych warunków pracy niezbędne jest wyznaczenie dodatkowych charakterystyk tych urządzeń. Są nimi między innymi wyznaczane w pracy charakterystyki ilustrujące zależności momentu obrotowego w funkcji obrotów, temperatury i inne.
EN
Paper presents a report of a research work that concerns possibilities of freight wagons modernization using new composite materials. The main aim of presented work was to verify the possibility of inference from the dynamic response of the wagon about the changes in its technical condition. During the presented works tests on real objects were carried out using Macro Fiber Composite (MFC) piezoelectric transducers glued to the freight wagon’s frame. The dynamical response of the wagon was measured while the object was driving. On the next stage the measured signal was generated on a laboratory stand using electrodynamic modal shaker and vibrations of the laboratory model were measured. Measured signals were juxtaposed on charts and analysed. The aim of this work was to verify if it is possible to detect the change in the system using measurements of vibrations that are being generated during exploitation of the freight wagon.
EN
In this paper the investigations of magnetostriction as well as DC magnetic properties for composites doped with Terfenol-D particles are presented. All investigations were performed for the materials with 35%, 46% and 70% volume fraction of the Terfenol-D particles surrounded by epoxy matrix. Moreover, the bulk Terfenol-D alloy was tested. The obtained results show that the magnetization of the composite materials increases with increasing the volume fraction of Terfenol-D particles. Similar dependence as for magnetization was observed for the magnetostriction measurements. Although the magnetostriction of composite material is smaller than for solid Terfenol-D it is still tens of times bigger than in case of traditional magnetostrictive materials. Obtained results gives opportunity to use these materials for variety applications such as actuators and sensors.
EN
The paper concerns an effect of the damping force controlling a vehicle suspension system. The investigated vehicle suspension system consists of innovatory Vacuum Packed Particles controllable dampers which allow controlling the vehicle body vibration. The main objective of performed and presented in the paper studies is to determine properties of the Vacuum Packed Particles (VPP) damper and propose a preliminary control strategy. The control in the vehicle suspension system can be realized by controlling the underpressure resulting in various jamming mechanisms in the granular core. Some algorithms of vibration control are also proposed and discussed.
10
Content available remote Magnetostriction of field-structural composite with Terfenol-D particles
EN
The paper describes the magnetomechanical properties of magnetostrictive composites containing a 70% volume fraction of Terfenol-D powder. Except for a reference specimen, composites were subjected to polarization during curing of the resin. The results of tests showed that polarization, its direction and type have an effect on the properties of the produced composites. The highest values of magnetostriction from the manufactured composite samples were obtained for the perpendicularly polarized specimen. For a pre-stress of 7 MPa the strain amounted to 720 ppm. The results indicate that the magnetostriction of the composite increases owing not only to the proper crystallographic orientation of the material, which is usually [1 1 2], but also to the proper preparation of the specimen in this case through polarization.
11
Content available remote Magnetorheological materials based on ethylene-octene elastomer
EN
Magnetorheological elastomer composites based on several magnetoactive fillers such as: carbonyl iron powder, gamma iron oxide, micro- and nano-sized Fe3O4 in ethylene-octene elastomer are reported and studied. To improve the dispersion of the applied fillers in a polymer matrix, ionic liquids were added during the process of composite preparation. To align the particles in the elastomer, the crosslinking process took place in a magnetic field. The effect of the amount of ferromagnetic particles and their arrangement on the microstructure and properties in relation to the external magnetic field was examined. It was found that the microstructure isotropy and anisotropy has a significant effect on the properties of the magnetorheological elastomers. Moreover, different amounts of magnetoactive fillers influence the mechanical properties (increase the tensile strength) of the composites compared to unfilled samples. The magnetic flux directed parallel to the sample surface increases the saturation magnetization of the composites. Magnetic anisotropy can also be seen by analyzing the shape of magnetization curves — steeper curves obtained for anisotropic samples support the hypothesis of a specific arrangement of the filler particles in the elastomer. The addition of ionic liquids improve the dispersion of the applied magnetoactive fillers (CIP and g-Fe2O3) in the elastomer matrix, which in turn favorably affected the network density, tensile properties and magnetorheological effect of the composites.
PL
Wytworzono magnetoreologiczne kompozyty elastomerowe (MRE) na bazie kopolimeru etylenowo-oktenowego z udziałem napełniaczy magnetoaktywnych: żelaza karbonylkowego (CIP), tlenku żelaza gamma (g-Fe2O3), mikro- lub nanometrycznego tlenku żelaza (Fe3O4). W celu zwiększenia stopnia zdyspergowania zastosowanych napełniaczy do układu dodawano różne ciecze jonowe. Kompozyty sieciowane pod wpływem pola magnetycznego wykazywały silną anizotropię cząstek napełniaczy spowodowaną ich specyficznym ułożeniem w matrycy elastomerowej. Stwierdzono, że dodatek napełniaczy magnetycznych wpływa na poprawę właściwości mechanicznych kompozytów; nastąpiło zwiększenie wytrzymałości na rozciąganie wulkanizatów w porównaniu z wytrzymałością próbek nienapełnionych. Stwierdzono również, że strumień magnetyczny ukierunkowany równolegle do powierzchni próbek, a tym samym do łańcuchów cząstek napełniaczy, powoduje zwiększenie magnetyzacji nasycenia kompozytów. Zastosowane ciecze jonowe z grupy soli alkiloamoniowych zwiększają stopień zdyspergowania magnetyków w matrycy elastomerowej, co wpływa na ich większą aktywność. W konsekwencji, napełniacze tworzą rozbudowaną strukturę w elastomerach. Dodatek cieczy jonowych wpływa także na zwiększenie gęstości sieci przestrzennej, poprawę właściwości wytrzymałościowych oraz na wielkość efektu magnetoreologicznego kompozytów.
EN
The objective of this paper is to show a designing process for actuators that utilizes shape-memory materials. Analytical studies are carried out to design a dot actuator to be used in an electronic Braille display. Shape-memory materials are a relatively new group of smart materials that exhibit the transformation of their internal structures in solid state phases resulting from external mechanical or thermal excitation. This unique property shows up as three phenomena: one- and two-way memory effects as well as superelasticity, which all significantly influence the change of both the mateńal properties and geometry. Hence, shape-memory mateńals are used as actuators effectively controlled by the above-mentioned types of excitation. The work presents the design guidelines for a proposed technical solution as well as the phenomenon utilized in the elaborated model of the actuator. The authors derived the mathematical descriptions for the proposed design configuration and an example of the calculations is shown. Moreover, the characteristics of the elaborated configuration are also discussed, taking into account the range of application areas.
PL
W artykule przedstawiono proces projektowania siłowników zbudowanych z materiałów z pamięcią kształtu z zastosowaniem metod analitycznych na przykładzie członu wykonawczego punktu Braille'a stosowanego w elektronicznych wyświetlaczach alfabetu Braille'a. Materiały z pamięcią kształtu są stosunkowo nową grupą materiałów inteligentnych, które charakteryzują się przebudową struktury wewnętrznej w fazach stałych na skutek zewnętrznego wymuszenia mechanicznego lub termicznego. Ta szczególna własność widoczna jest w trzech zjawiskach: jednokierunkowego oraz dwukierunkowego efektu pamięci kształtu oraz supersprężystości, które istotnie wpływają na zmianę wartości parametrów materiałowych oraz geometrię. W efekcie materiały z pamięcią kształtu znajdują zastosowanie jako napędy w członach wykonawczych, w których skok siłownika jest funkcją jednego z wyżej wymienionych wymuszeń. W artykule przedstawiono założenia projektowe zaproponowanego rozwiązania technicznego oraz omówiono zjawisko wykorzystywane w opracowanym modelu. Autorzy wyprowadzili odpowiednie zależności ilościowe dla przyjętej konfiguracji siłownika, których użycie zaprezentowano na przykładzie obliczeniowym. Poddano dyskusji charakterystyki zaproponowanej konfiguracji projektowej, z uwzględnieniem obszaru jej zastosowania.
EN
In this paper, a mathematical model of electromechanical transduction of Ionic Polymer-Metal Composites is presented. The aim of the research was to create a physics-based, geometrically scalable model to use in control systems. The relation between actuating voltage and the tip displacement was described with a transfer function. The model is derived from the basic physical properties of re-searched materials. To calculate the final transfer function, two impedance models are considered – with and without neglecting the re-sistance of the metal electrodes. In this paper, the model with non-zero electrode resistance is calculated. Later, the model is simplified (taking the physical properties into account) and the numerical values based on the parameters of the samples are calculated. The simpli-fications allow the model to predict the response to low-frequency sine wave actuation. The frequency-domain characteristics of the sam-ples were created experimentally and compared to the model. The results have proven the accuracy of the model.
14
Content available remote Zasada wzajemności w elektrostrykcji
EN
The paper contains derivation of reciprocity principle for boundary problem of electrostriction. The results obtained in this work can become the theoretical basis to formulate the numerical solutions of different scientific and engineering problems connected with electrostrictive materials.
EN
In this paper, a recurrent neural network structure is proposed for the modeling of the behavior of shape memory alloy springs. Numerous mathematical modeling and experimental evaluations show that the force exerted by SMAs, aside from their length and applied voltages, depends on the loading path. Therefore, in addition to the applied voltage and deformation, a feedback of the voltage applied to, and the force exerted by the SMA spring in the previous time step is included in the inputs to this neural network to represent the loading path. Fed by adequate inputs, the NN estimates the output force of the spring. The results of some thermal loadings of the spring at various fixed lengths and mechanical loadings at various constant voltages are used to train the NN. The performance of the NN model is then evaluated for some constant weight loadings which are not learnt by the NN. Simulation results indicate that compared to other neural network structures, the proposed structure learns the behavior of the SMA spring faster (in less iteration). Moreover, it provides a more general model, i.e. this NN model effectively estimates the output force for almost all possible loadings.
16
Content available remote Position regulation of magnetic shape memory actuator
EN
Purpose: This paper presents materials with magnetic shape memory. These materials are a new group of smart materials, which distinguished by large deformations (up to 10%), and relatively high operating frequencies. Authors used in research samples made of Ni2MnGa alloy in order to find out of their capabilities in transducers design applications and for better understanding their nonlinear behavior. Design/methodology/approach: For research purposes, authors designed laboratory electro-mechanical transducer, which works in spring retuned operating mode. This transducer is connected with dSPACE system used for regulation and data acquisition process. Coils were connected with programmable DC power supply. Findings: This design of transducer was for Authors a first attempt of practical application of MSMA. Results help in: modelling process of hysteresis for future open loop regulation, finding out optimal working conditions and scope of available operating parameters. Changes will be applied in next transducers design e.g. shape of magnetic circuit and these transducers will have more compact design. Research limitations/implications: Step responses of material are much worse than values given by manufacturer, because response of controllable power supply is up to 0.1 s. Another problem were stiffness of transducer and repeatability of obtaining results, but since modifications it has been successfully eliminated. Practical implications: Implemented in the examined transducer operating mode is identical to the principle of operation of an electromagnetic transducers used in design of electro-hydraulic and electro-pneumatic cartridge valves. In these valves solenoid moves a spool and after a power cut due to the spring tense, it returns to base position. Future work will focus on their replacement by a transducers designed with the use of MSMA. Originality/value: In this paper design with detailed description is presented. It can be treated as guidelines for other scientists who would like to design similar transducers. The article is the base for further research.
17
Content available remote Prosthesis design driven by electroactive polymers
EN
Applications of dielectric elastomer (DE) actuators are presented in this paper. Dielectric elastomers (a type of electroactive polymer) are one the most promising smart materials. They consist of two flexible electrodes and a dielectric film between them. After applying voltage (3–5 kV) to the electrodes, the thickness of the polymer layer lowers. Changes of the thickness can be indirectly measured , enabling the element to work as a sensor. A self-sensing and energy harvesting elements are also described. Two applications are described – an active orthosis and a force feedback device.
PL
W artykule przedstawione są zastosowania siłowników opartych na elastomerach dielektrycznych. Materiały te są jednym z najbardziej obiecujących przedstawicieli materiałów inteligentnych, a dokładniej – polimerów elektroaktywnych. Składają się z dwu podatnych elektrod i warstwy polimerowego dielektryka pomiędzy nimi. Po przyłożeniu napięcia aktywacji (ok. 3–5 kV) zmniejsza się grubość tej warstwy. Ta zmiana grubości może być mierzona w sposób pośredni, co pozwala na pracę element jako czujnika. Opisano tryb jednoczesnej pracy siłownikowo-czujnikowej i magazynowania energii. Dwa zastosowania zostały szczegółowo opisane: aktywny wyciąg ortopedyczny palca i urządzenie do siłowego sprzężenia zwrotnego.
EN
A lead free ceramic composite 0.9BaFe0.5Nb0.5O3-0.1Ni0.5Zn0.5Fe2O4 (BFN-NZF) with ferroelectromagnetic properties have been obtained in presented work. Ceramic composite powder obtained from the simple oxides Fe2O3, Nb2O5, ZnO, NiO and barium carbonate BaCO3. The composition of the composite was chosen so that the ratio of the BFN and NZF components was 90:10. The synthesis of components of BFN-NZF composite was performed using the calcination method. Final densification of synthesized powder has been done using free sintering. The XRD, the microstructure, EDS and dielectric investigations were performed. For comparison of the BFN ceramic and the BFN-NZF composites, temperature and frequency impedance research was conducted. Relaxation phenomena were observed at temperatures above 235°C in the BFN ceramic and above 150°C in the BFN-NZF composite. Obtained results show the coexistence of ferroelectric and magnetic properties. Such properties of obtained composites give the possibility to use them in magnetoelectric transducers.
PL
W niniejszej pracy otrzymano bezołowiowy ceramiczny kompozyt 0.9BaFe0.5Nb0.5O3-0.1Ni0.5Zn0.5Fe2O4 (BFN-NZF) o właściwościach ferroelektromagnetycznych. Ceramiczny proszek kompozytowy otrzymano na bazie prostych tlenków Fe2O3, Nb2O5, ZnO, NiO oraz węglanu baru BaCO3. Skład kompozytu został dobrany w taki sposób, aby stosunek składników BFN i NZF wynosił 90:10. Syntezę składników kompozytu BFN-NZF przeprowadzono metodą kalcynacji proszków. Końcowe zagęszczanie syntetyzowanego proszku zostało przeprowadzone metodą spiekania swobodnego. Zostały przeprowadzone badania XRD. mikrostrukturalne. EDS oraz właściwości dielektrycznych. Dla porównania ceramiki BFN i kompozytu BFN-NZF przeprowadzono temperaturowe i częstotliwościowe badania impedancyjne. Zjawiska relaksacyjne obserwowano w temperaturze powyżej 235°C w BFN ceramiki i powyżej 150°C w BFN-NZF kompozytu. Uzyskane rezultaty badań wskazują na współistnienie ferroelektrycznych i magnetycznych właściwości. Właściwości otrzymanych kompozytów dają możliwość wykorzystania ich do budowy przetworników magnetoelektrycznych.
EN
The nonlinear mathematical model of behavior of controllable viscosity fluid (CVF) under applied external field is presented. A large family of these fluids is commonly used to control responding forces of dampers in vibration control applications. The responding force of a damper with CVF has two components. The first one - uncontrollable - is proportional to the viscosity of a base fluid and velocity of its motion, the second one, which is controllable, depends on the strength of the applied external field. Both are involved in the process of dissipation of unwanted energy from the vibrating systems. An equivalent damping factor based on the principle of energy dissipated during one cycle of damper work under a constant strength external field was calculated. When mass or stiffness is variable the equivalent damping factor can be set accordingly by adjusting the strength of external field to have vibrating damped system purposely/continuously working in the critical or other chosen state. This paper also presents cases of applying periodically changing strengths of an external field synchronized with cycles of periodical motion of the vibrating system to continuously control the damping force within each cycle.
20
Content available Smart materials as modern engineering substances
EN
The article presents the type and use of intelligent materials in aviation and medicine. Their basic features and properties have been discussed. Moreover, the authors quote examples of different uses of intelligent materials, both the existing ones and those in design and development stages. Their use is claimed to be increasing the efficiency and reliability of processes and equipment as well as facilitates the development of new mechanisms.
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