AN APPROXIMATE METHOD FOR ANALYZING THE VIBRATIONS OF STIFFENED PLATES AND SHELLS.
CAMBRIDGE ACOUSTICAL ASSOCIATES INC MASS
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The report develops an approximate method for analyzing the vibrations of plates and shells which are stiffened by parallel stiffeners running in one direction. The method involves the application of two distinct approximation techniques. The first consists of relating the stiffened structure to an equivalent orthotropic structure of uniform thickness by, at most, five non-dimensional parameters these parameters are related to the effective moduli of elasticity, the effective radii of gyration and the average mass per unit area appropriate to the stiffened structure. The second technique is applied when a given vibration pattern, i. e. a given set of eigenfunctions, possesses more than one mode of vibration it consists of applying to the stiffened structure certain modal approximations which have first been used successfully in analyzing the virbrations of the corresponding uniform isotropic structure. The method is applied to the vibrations of a thin stiffened rectangular plate, a thick stiffened rectangular plate, and a thin ring-stiffened circular cylindrical shell. Author