Abstract
Studying the interaction of sound with cylindrical shells immersed in water is essential and helpful to improving underwater target detection and classification algorithms. Elastic cylindrical shells often occur as part of double-layered shell and have been widely used in marine and aerospace area. Acoustic waves are easy to be transmitted through the outer shell to the interior especially at low frequencies, thus directly being scattered by the inner shell and the rings in water between double-layered shells. Therefore, the externally ring-stiffened cylindrical shell is investigated in this paper. An experiment was conducted that measured the acoustic scattering. A hybrid 2-D/3-D finite-element modelling technique is employed to numerically calculate the scattering characteristics. Good qualitative agreement is found between numerical calculations and experimental measurement. An approximate analytical expression is given explicitly to identify the Bragg wave trajectories in the frequency-angle spectrum. It also has been shown that the rings not only affect the dynamic response of shell and indirectly influence the exterior scattered field, but also become direct acoustic scatterers in water and increase the target cross section especially at oblique incidence.
Highlights
Elastic cylindrical shells often occur as part of double shell constructions and have been widely used in marine and aerospace research
Various inclusions can be modelled as beams, rods, or thin plates, which are equivalent to the forces and bending moments coupling with the outer shell, and each type of resonance can be associated with a particular type of interaction between the shell and the inclusions
Acoustic waves are transmitted through the outer shell to the interior, especially at low frequencies, and the waves are scattered by the inner shell and the rings in the water area between double-layered shells
Summary
Elastic cylindrical shells often occur as part of double shell constructions and have been widely used in marine and aerospace research. Previous studies focused on the scattering from the internally ring-stiffened cylindrical shells [1,2,3,4,5] and other inner structures [6,7,8,9]. Double-layered shells are structurally connected to each other by common frames or rings thereby significantly affecting the sound scattered or radiated from the shells. The acoustic scattering from an externally ring-stiffened cylindrical shell is investigated as a simplification of double- layered shells. The hybrid 2-D/3D FE model has been applied to investigate sound propagation in the ocean and the scattering from complex objects [12]. The hybrid 2-D/3-D FE modelling is introduced and applied to calculate the frequency-angle spectrum in Sec..
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
