Free vibration of longitudinally stiffened curved panels with cutout

Free vibration characteristics of longitudinally stiffened square panels with symmetrical square cutouts are investigated by using the finite-element method. A rectangular shell element with seven degrees of freedom per node together with a beam element of seven degrees of freedom per node is used for the analysis. Studies are carried out on unstiffened as well as stiffened panels keeping the size, weight and boundary conditions the same. Numerical results indicate that the frequency of the stiffened panel is higher. Maximum increase in fundamental frequency is observed on the panel with the smallest radius of curvature. © 1999 Academic Press.