Since the significant growth of interest in soft robotics, artificial muscles and biomimetics, soft, capacitive dielectric elastomer sensors (DES) have been in the focus of development. However, when including a sensor into any device, tool or, for example, a machine element, there are several factors which have to be considered, e.g., the ease of embedding the sensor, the maintenance of the functionality of the machine element, as well as the quality of the embedded sensors and their reproducibility. In this work, we will focus on the quality of the sensor and present a procedure for manufacturing multi-layer capacitive strain sensors. In order to assess the influence of different manufacturing processes on the quality of capacitive DES, a variety of thin multi-layer sensors were fabricated. Furthermore, using an LCR meter, the equivalent electrical capacitances (C) at the two sensor contacts were measured. It is shown that C varies depending on the quality of the electrodes. By testing multi-layer DES (ML-DES) with an electrode diameter of d electrode = 3 mm, with three and four electrode layers, a maximum capacitance of C 0 = 6.7 pF and C 0 = 10.5 pF was achieved for the undeformed sensor, respectively. The obtained capacitance values show that following the presented recommendations for creation the electrodes enables to improve the reproducibility and quality of the manufactured ML-DES. The fabricated sensor is soft and deformable due to the compliance of the elastomeric film used. Such a capacitive ML-DES can be used, for example, as a soft strain sensor implemented into the elastic element of a jaw coupling.
Im Zuge einer Eisenbahnquerung des Suez‐Kanals entsteht zur Zeit bei El Ferdan in der Nähe von Ismaelia eine doppelarmige Drehbrücke, die wechselweise eine eingleisige Eisenbahnlinie mit 1435 mm Spurweite oder eine zweispurige Straße von 9,2 m Fahrbahnbreite überführen kann. Das gesamte Brückenbauwerk besteht aus zwei gleichartigen Drehbrücken von je ca. 5000 t Gesamtgewicht, die auf der West‐ und Ostseite des Suezkanals angeordnet sind (Western Span und Eastern Span). Beide Drehbrücken haben Kragarme von 170 m und 150 m Länge, wobei der längere Kragarm über den Kanal einschwenkt. Mit den Stützweiten von 150 ‐ 340 ‐ 150 m wird diese Brücke bei der Übergabe an die Ägyptische Staatsbahn im Januar 2001 die größte Drehbrücke der Welt sein.Der vorliegende Beitrag beschreibt die konstruktiven Besonderheiten des Maschinenbaus, der Antriebs‐ und Steuerungstechnik. Das Drehlager auf der Westseite ist fertig montiert und die Montage des Pylones und Auslegers haben begonnen. Die Fundamentarbeiten auf der Ostseite werden im Februar abgeschlossen, so daß anschließend das Drehlager auf der Ostseite montiert werden kann. Das Ende der Gesamtmontage einschließlich Elektrotechnik ist für September 2000 geplant. Daran wird sich eine umfangreiche Funktionserprobung anschließen, so daß am 31.01.2001 die größte Drehbrücke der Welt für den Verkehr freigegeben werden kann.
The high costs for the development, erecting und operation of wind turbines are connected to very high expectations for a reliable and low-maintenance operation and require a precise knowledge of the loads and stresses to be expected. The transfer of knowledge from smaller wind turbines and possibly other concepts succeeds only to a limited extent. Rather comprehensive simulation approaches to determine wind loads, operational conditions and possible resonances are already used since many years. By means of simulation models, the natural frequencies can be determined and compared to possible excitations. The simulation of the operation of the wind turbine under different wind speeds allows the calculation of component loads as a basis for the further design process.The paper concentrates on the possibility of using multibody-system simulation models in the design process of gearboxes for wind turbines and the associated dynamic properties of the complete system by the example of the 15 MW reference wind turbine of the National Renewable Energy Laboratory (NREL). The comprehensive factors which influence the load distribution in the gearing of the first planetary gear stage require a detailed consideration of the elasticity of all relevant components. Based on the developed gearbox design and a detailed multibody-system simulation model, the influence of the level of detail of the model on the resulting natural frequencies and the occurring load distribution in the gearing of the planetary gear stages can be discussed. The present results show that findings on the required level of detail of simulation models cannot be applied to new turbines independently of the power class.
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