Browsing by Author "Zhou, L."

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Cutout reinforcements for shear loaded laminate and sandwich composite panels
    (Springer Science Business Media, 2008-06-30T00:00:00Z) Guo, Shijun J.; Zhou, L.; Cheung, C. W.
    This paper presents the numerical and experimental studies of shear loaded laminated and sandwich carbon/epoxy composite panels with cutouts and reinforcements aiming at reducing the cutout stress concentration and increasing the buckling stability of the panels. The effect of different cutout sizes and the design and materials of cutout reinforcements on the stress and buckling behaviour of the panels are evaluated. For the sandwich panels with a range of cutout size and a constant weight, an optimal ratio of the core to the face thickness has been studied for the maximum buckling stability. The finite element method and an analytical method are employed to perform parametric studies. In both constant stress and constant displacement shear loading conditions, the results are in very good agreement with those obtained from experiment for selected cutout reinforcement cases. Conclusions are drawn on the cutout reinforcement design and improvement of stress concentration and buckling behaviour of shear loaded laminated and sandwich composite panels with cutouts.
  • Thumbnail Image
    ItemOpen Access
    Helicopter gearbox bearing fault detection using separation techniques and envelope analysis
    (IEEE, 2017-01-19) Zhou, L.; Duan, F.; Mba, David; Corsar, Michael; Greaves, Matthew J.; Sampath, Suresh; Elasha, Faris
    The main gearbox (MGB) is a crucial part of a helicopter. MGB bearings suffer intensively from stress and friction during flights hence concerns for their health condition and detecting potential defects become critical for the sake of operation safety and system reliability. In this study, bearing defects were seeded in the second epicyclic stage bearing of a commercial Class A helicopter MGB. Vibration and tachometer signals were recorded simultaneously for the purpose of fault diagnosis. The tests were carried out at different power and speed conditions for various seeded bearing defects. This paper presents a comparison of signal processing techniques employed to identify the presence of the defects masked by strong background noise generated from an operation helicopter MGB.