Acoustic response of thin-walled, orthogonally stiffened cylinders

A semi-analytical model is developed to predict the acoustic response of thinwalled, orthogonally stiffened cylinders. The free vibration model is solved by the approximate assumed-modes method. The excitation of the normal modes is considered in terms of the Joint Acceptance Function (JAF) for incident acoustic harmonic plane waves. The surface pressure distribution is obtained by the shallow shell approximation, where the blocked excitation pressure is double the incident pressure, and by the 2-D rigid cylinder approximation considering the sound scattering. The acoustic response is then compared with that of a fully coupled FE-BE model. An efficient estimation of the response can be obtained by the two models over a certain range of accuracy. Numerical results for different structural configurations are then given. The effect of the stiffeners on the modal characteristics is discussed. It also illustrates the modal contribution to the total displacement response and addresses both circumferential and axial orthogonally stiffened cylinder arrangements