The effect of cutout positioning on the dynamic characteristics of a curved composite panel

An investigation of the effects of eccentrically located square cutouts on the natural frequencies and mode shapes of circular, cylindrical composite panels was conducted. A video holographic interferometry technique was used to determine experimentally the first five natural frequencies and mode shapes of the panels. Numerically, predictions for these same data were obtained using a finite element method. A clamped-free-clamped-free boundary condition was selected for this study. Cutouts were eccentrically located in both the circumferential and axial directions. The experimental and numerical results for both the natural frequencies and mode shapes correlated well. The per cent differences between the experimental and numerical frequencies averaged around 7% and were in all cases less than 10%. It was observed that, in general, panels with eccentrically located cutouts experienced only small frequency deviations from those with centered cutouts. The amount of variation observed tended to increase with cutout size.