This paper presents an experimental-theoretical investigation of the influence of tip sweep on the natural frequencies of rotating aluminum and composite solid-section beams. An in-vacuo rotor test facility was used to test the beams for their vibration characteristics. Induced-strain actuation via piezoceramic elements was used to excite the beams, and strain gauges were used to measure the response of the beams. The theoretical frequencies were calculated using a finite-element structural model in which the beam had one elastic axis for the straight portion and another elastic axis for the swept portion. Nonlinear transformation relations were used to connect the elastic axes of the straight and swept segments of the beam. Natural frequencies of the beams were obtained by carrying out linearized free vibration analysis about their deformed states. For better accuracy in the prediction of these frequencies, graded finite-element mesh with finer mesh at the junction of straight and swept segments of the beam was used. Good correlation between experiment and theory was achieved for these beams. Modeling the sweep as an offset of the center of gravity from the assumed straight elastic axis was found to be inadequate for predicting the natural frequencies of swept tip beams.
The natural frequencies of rotating composite beams with tip sweep
Die Eigenfrequenzen von rotierenden Verbundbalken mit abgeknickten Endspitzen
Journal of the American Helicopter Society ; 41 , 1 ; 29-36
1996
8 Seiten, 23 Bilder, 1 Tabelle, 12 Quellen
Aufsatz (Zeitschrift)
Englisch
Rotor (Drehflügel) , Verbundwerkstoff , Resonanzfrequenz , Systemanalyse , Rechenmodell , Vergleichsmessung , Versuchsstand , Schwingungsanregung , dynamisches Verhalten , Finite-Elemente-Methode , Nichtlinearität , elastische Verformung , carbonfaserverstärkter Kunststoff , Epoxidharz , Piezokeramik , Polarisation von Licht , Verifikation , Rechengenauigkeit
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