NONLINEAR VIBRATIONS OF PERIODICALLY STIFFENED PLATES

A study is presented of the vibration and sound radiation of airplane fuselage structures when they are excited by intense driving fields. The fuselage structure is idealized as a section of a shell which is supported on a grid of periodically spaced stiffeners. An analytical method is presented for including nonlinear effects in the analysis of the vibrations of periodically stiffened plate structures. The approach consists of first determining the mode shapes and natural frequencies of a finite periodic structure when nonlinearities are neglected. These mode shapes are then used as approximate shape functions in a nonlinear model of the structure. The result is a coupled system of nonlinear ordinary differential equations which are solved numerically.