Vibration Characteristics of Stiffened Plates

Abstract

This paper describes methods of calculating natural frequencies of free flexural vibration of rectangular plates which have stiffeners parallel to one edge. An approximate frequency equation is derived for a clamped plate with closely spaced stiffeners by extending the Rayleigh method as applied by Warburton (1)† to rectangular isotropic plates. For a plate containing a single central stiffener, an exact frequency equation is derived for simply supported edges and an approximate fundamental frequency equation is derived for clamped edges. Comparison between observed and calculated frequencies is made and the practical effect of stiffening upon natural frequencies is discussed. The application of the Rayleigh method to the calculation of natural frequencies of integrally stiffened plates is illustrated by calculating frequencies determined by Hoppmann and Thorkildsen (2).