On the multi-modal behavior and inner resonances of stiffened shells

A numerical and experimental investigation on the effects of axial and circumferential periodically distributed stiffeners on shells is conducted in this work. The Inhomogeneous Wave Correlation (IWC) method is used to characterize the dynamic behavior and the wave propagation in the structures. The dispersion curves are calculated in two orthogonal directions (axial and circumferential), capturing the band-gaps related to the geometric periodicity and multi-modal behavior (in terms of uncoupled flexural stiffeners and skin motions). The experimental tests are conducted on a stiffened aluminum aircraft sidewall panel under point mechanical excitations and laser doppler velocimeter acquisition; numerical simulations are computed using punctual harmonic excitation in a Finite Element framework.