On the study of vibrational interactions of an internal substructure with a main structure submerged in water and its acoustic radiations using admittance approach

Abstract

It is important and practical to design an internal substructure for supporting machines which generates vibration sources for a main submerged stiffened shell structure. Vibration propagates from the internal supporting structure to the wetted shell structure, thus radiating acoustic energy into water. The present study can be divided into two categories: 1. the main wetted structure, including stiffeners and bulkheads, etc., radiates acoustic energy into water subject to forces which is the junction interacting forces arisen from the vibrating machine, 2. the interaction force pertains to the coupling dynamic characteristics between wetted structure and the internal structure. An admittance approach is adopted to characterize individual structures and the coupled equation is derived by continuity of displacement variables and equaling forces with opposite sign at the junction of connected structures. Admittance matrices are computed by using junction forces between the structures whereas the responded displacements at the junctions are the elements of the admittance matrices. The coupled admittance equation is complex symmetric matrix. An eigenvalue analysis is performed to investigate the interaction junction forces, accordingly, the radiation characteristics of the coupled main wetted structure under fluid loading in connection with supporting internal structures.It is important and practical to design an internal substructure for supporting machines which generates vibration sources for a main submerged stiffened shell structure. Vibration propagates from the internal supporting structure to the wetted shell structure, thus radiating acoustic energy into water. The present study can be divided into two categories: 1. the main wetted structure, including stiffeners and bulkheads, etc., radiates acoustic energy into water subject to forces which is the junction interacting forces arisen from the vibrating machine, 2. the interaction force pertains to the coupling dynamic characteristics between wetted structure and the internal structure. An admittance approach is adopted to characterize individual structures and the coupled equation is derived by continuity of displacement variables and equaling forces with opposite sign at the junction of connected structures. Admittance matrices are computed by using junction forces between the structures whereas the responded d...