Effects of concentrated elements on vibro-acoustic characteristics of a circular ring considering both external and internal fluids

This study focuses on the vibro-acoustic characteristics of submerged structures with concentrated elements and filled with fluid. A weak formulation is developed based on the modified variational principle. The accurate energy expressions for both structural and acoustic domains are incorporated into the coupled vibro-acoustic model. With introduced Lagrangian multipliers, a domain partitioning technique is developed to divide the whole acoustic domain into several subdomains. The continuity conditions between adjacent subdomains are further guaranteed by the least square weighted residual method working on the common interfaces. To satisfy the Sommerfeld radiation condition, an artificial boundary with the local absorbing boundary condition is adopted to truncate the infinite external acoustic domain. A water-submerged and air-filled bidimensional circular ring with concentrated elements is used as the research object to validate the accuracy of the proposed approach. The concentrated elements are considered as lumped masses with elastic boundary conditions. The structural displacements and acoustic pressures are expanded by the Fourier series and Chebyshev orthogonal polynomials. Furthermore, the effects of the concentrated elements on the coupled vibro-acoustic responses are carefully investigated, as considering different distribution patterns.