Wave Mode Conversion in Stiffened Cylindrical Shells With Periodic Axial Curvature

Free wave propagation in periodically stiffened cylindrical shells is investigated using a periodic finite element method developed by the authors. The modification of longitudinal wave modes was a primary objective because of their long wavelengths and poor attenuation characteristics. Cylinder configurations that utilize periodic axial curvature are examined and are shown to have significantly more coupling between longitudinal and fiexural wave modes than cylinders without axial curvature. This coupling significantly modifies the stop and pass band behavior. In this paper, the periodic finite element method is first reviewed. The method is then applied to a one-dimensional periodic structure consisting of circular beam sections. The longitudinal/flexural wave mode conversion in this simple structure is illustrated. Finally, results for cylindrical shells with and without axial curvature are presented.