Dynamik der Baukonstruktionen

Petersen, Christian; Werkle, Horst

doi:10.1007/978-3-8348-2109-6

Cited by 55 publications

(49 citation statements)

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“…According to the literature on dynamics of civil structures according to Petersen, the logarithmic decrement for overall structural damping can be obtained by a sum of the material damping, the damping of the tower structure, and the damping of the foundation. The material damping of steel is given by a minimum value of δ s t e e l =0.005.…”

Section: Resultsmentioning

confidence: 99%

Experimental identification of modal parameters of an industrial 2‐MW wind turbine

Zierath¹,

Rachholz

Rosenow³

et al. 2018

Wind Energy

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This contribution presents modal testing of a 2-MW wind turbine on a 100-m tubular tower with a 93-m rotor developed by W2E Wind to Energy GmbH. This research is part of the DYNAWIND project of the University of Rostock and W2E. Beside classical modal analysis schemes, this contribution mainly focusses on the application of operational modal analysis techniques to a wind turbine. Specific problems are addressed, and hints for modal testing on wind turbines are given. Furthermore, an effective measurement setup is proposed for identification of the modal parameters of a wind turbine. The measurement campaign is divided in two parts. First, a measurement campaign using 8 sensor positions on a rotor blade was done while the rotor is lying on ground. Second, a detailed measurement campaign was done on the entire wind turbine with the rotor locked in Y position using 61 sensor positions on the tower, the mainframe, the gearbox, the generator, and the low-voltage unit. While the rotor blade was tested by classical and operational modal analysis techniques, the entire wind turbine was tested by operational modal analysis techniques only. The mode shapes and eigenfrequencies of the wind turbine identified within the measurement campaigns are within the expected range of the design values of the wind turbine. But in contrast, the damping ratios differ strongly from those given in guidelines and literature. Furthermore, a strong influence of aerodynamic damping compared to structural damping is observed for the first tower mode even for a parked wind turbine. KEYWORDS modal testing, operational modal analysis, 2-MW wind turbine INTRODUCTIONThe life cycle of a wind turbine is mainly influenced by its dynamics. To avoid resonances in the variable speed range of a wind turbine, resonant frequencies of the entire turbine including substructure resonant frequencies as well as harmonic excitations must be known accurately. Whereas the harmonic excitation frequencies are multiples of the rotational speed and well known, resonant frequencies have to be calculated using a proper simulation model or identified experimentally. A verification of calculated results by measurements is the preferable approach. So the extensive knowledge and the deep understanding of the dynamics of a wind turbine allows precise prediction of its behaviour. For the identification of the modal parameters the classical modal analysis (CMA) and the operational modal analysis (OMA) are chosen.The lowest resonant frequencies of the entire turbine and corresponding mode shapes, affected mainly by tower and blades, have to be considered with respect to the first and third-order excitations (rotational frequency and blade passing frequency, respectively) to avoid severe resonance problems during operation. Resonant frequencies of the main frame have to be considered with respect to higher excitation orders resulting mainly from the rotational frequency of the generator. Dynamic deflections of the main frame, potentially inducing undesirable loads on the drive tra...

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Section: Resultsmentioning

confidence: 99%

Experimental identification of modal parameters of an industrial 2‐MW wind turbine

Zierath¹,

Rachholz

Rosenow³

et al. 2018

Wind Energy

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“…Betrachtet man ein frei schwingendes gedämpftes System, beispielsweise den Einmassenschwinger, so wird dieses aufgrund der Eigendämpfung mit der Zeit wieder in seine Ruhelage zurückkehren [13]. In diesem Beitrag wird vor allem auf die Eigendämpfung des Flüssigkeitstilgers selbst sowie auf den Einfluss dieser Dämpfung auf das schwingende Hauptsystem eingegangen.…”

Section: Dämpfungunclassified

“…In diesem Beitrag wird vor allem auf die Eigendämpfung des Flüssigkeitstilgers selbst sowie auf den Einfluss dieser Dämpfung auf das schwingende Hauptsystem eingegangen. Für eine effektive Wirkung des Schwingungsdämpfers ist die Abstimmung seiner dynamischen Parameter auf die Eigenschaften des Hauptsystems (Schornsteine, Windkraftanlagen) essenziell [11, 13, 15, 16, 17]. Meist werden hierfür die Abstimmungskriterien nach D EN H ARTOG angewendet [10].…”

Section: Dämpfungunclassified

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Dämpfungsverhalten unterschiedlicher Fluide in einem Flüssigkeitstilgersystem

Schellander¹,

Strauß²

2016

Bautechnik

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Damping behavior of different fluids used for a Tuned Liquid Column Damper SystemTuned liquid column dampers (TLCD) represent a good alternative to other commonly used damping systems applied on engineering structures. The use of an additional mass causes a contrary motion in relation to the main oscillating system. This contrary motion enables an efficient way to mitigate unwanted structural vibrations. To obtain high damping efficiencies certain parameters of the TLCD must be optimized and adjusted to the main system. Important parameters would be the mass -m, the eigenfrequency of the damper f T , the stiffness and of course the damping of the system itself. The theoretical and experimental investigations of certain parameters are the aim of this contribution. The main focus was on the damping term of the TLCD. Since it is strongly dependent on the rheological parameters of the fluid, such as viscosity, shear rates, density etc. different fluids were tested and after evaluation compared. To execute these experiments, a test stand has been designed and built. So the main aim of this research work is to theoretically explain fundamental fluid parameters and in a further step to show how a change of these parameters changes the damping behavior of the TLCD.

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“…a) Detail of the carbon steel rig used to clamp the sub-component during cyclic excitation, (b) Detail of the excitation system composed of the eccentric mass driven by the stepper motor accommodated on a tailor-made aluminium support and the tuning mass mounted on the bottom beam sideeventually obtained by equation(31), according to Petersen[35].…”

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confidence: 99%

An Improved Sub-component Fatigue Testing Method for Material Characterization

2018

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Dynamik der Baukonstruktionen

Cited by 55 publications

References 0 publications

Experimental identification of modal parameters of an industrial 2‐MW wind turbine

Experimental identification of modal parameters of an industrial 2‐MW wind turbine

Dämpfungsverhalten unterschiedlicher Fluide in einem Flüssigkeitstilgersystem

An Improved Sub-component Fatigue Testing Method for Material Characterization

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