Eccentricity Effects of Square Cutouts on the Natural Frequencies and Mode Shapes of Curved Rectangular Composite Panels.

摘要

The purpose of this study was to investigate the eccentricity of square cutouts on the natural frequencies and mode shapes of circular, cylindrical composite panels. A video holographic interferometry technique was used to determine the first five natural frequencies and mode shapes of the panels. Analytically, predictions for this same data were obtained using the STAGSC-1 finite element program. The primary objective was to examine how cutout eccentricity altered the dynamic characteristics of the panel. A secondary objective was to continue the verification of the dynamic analysis capabilities of the STAGSC-1 program. The panels examined were constructed of Graphite/epoxy (Gr/Ep) and had an arclength, height, and radius of curvature of 12 inches, 11 inches, and 12 inches, respectively. A 0/-45/+45/90s ply layup was used, which resulted in a panel thickness of 0.04 inches. A clamped-free-clamped-free boundary condition was selected for this study. Cutouts eccentrically located in both the circumferential and tangential directions were considered. Experimentally, 2 inch and 4 inch square cutouts were studied, while the analytical analysis included 2 inch, 3 inch, 4 inch, and 5 inch square cutouts. Only the frequencies are presented for the panels with 3 inch and 5 inch cutouts. It was observed that, in general, eccentrically located cutouts caused small frequency variations when compared to centered cutouts. Theses. (rrh)