Now showing 1 - 3 of 3
  • Publication
    Metadata only
    Predicting Failure of Additively Manufactured Specimens with Holes
    (2023)
    Schmeier, Gina Eileen Chiara
    ;
    Tröger, Clara
    ;
    Kwon, Young W.
    ;
  • Publication
    Metadata only
    Study of fluid–structure interaction with undulating flow using channel driven cavity flow system
    (Springer International Publishing, 2021-12)
    Klein, N.
    ;
    Kwon, Y. W.
    ;
    Didoszak, J. M.
    ;
    Burns, E.
    ;
    Fluid–structure interaction (FSI) induced by undulated flows was investigated using a channel driven cavity flow (CDCF) system. The bottom of the cavity section has a flexible plate made of either an aluminum alloy or carbon fiber composite, which interacts with flows in the cavity. Undulating flows were generated by controlling a series of solenoid valves programmed to interrupt the flow at various different frequencies from 0.5 to 1.25 Hz. Mean flow velocity was also varied for each given undulation frequency. The dynamic motion of the flexible test panel, made of aluminum alloy or carbon fiber composite, was measured for transverse deflections using laser displacement sensors. The study showed that the structural response was very dependent on the input flow. The plate vibrational modes had three to five dominant frequencies ranging from the undulated flow frequencies to about 5.0 Hz. Those frequencies were either at or very close to the multiples of the flow frequencies. The most dominant frequency was not always the same as the flow frequency, but it varied depending on the applied flow frequency.
  • Publication
    Metadata only
    Experimental noise source identification in a fuselage test environment based on nearfield acoustical holography
    (2021-11) ; ;
    Wandel, M.
    ;
    Thomas, C.
    A major challenge in the subject of noise exposure in airplanes is to achieve a desired transmission loss of lightweight structures in the low-frequency range. To make use of appropriate noise reduction methods, identification of dominant acoustic sources is required. It is possible to determine noise sources by measuring the sound field quantity, sound pressure, as well as its gradient and calculating sound intensity by post-processing. Since such a measurement procedure entails a large amount of resources, alternatives need to be established. With nearfield acoustical holography in the 1980s, a method came into play which enabled engineers to inversely determine sources of sound by just measuring sound pressures at easily accessible locations in the hydrodynamic nearfield of sound-emitting structures. This article presents an application of nearfield acoustical holography in the aircraft fuselage model Acoustic Flight-Lab at the Center of Applied Aeronautical Research in Hamburg, Germany. The necessary sound pressure measurement takes one hour approximately and is carried out by a self-moving microphone frame. In result, one gets a complete picture of active sound intensity at cavity boundaries up to a frequency of 300 Hz. Results are compared to measurement data.