Vibratory response and acoustic radiation of a finite cylindrical shell partially covered with circumferential compliant layers

This work focuses on the vibration and acoustic radiation of a finite circular cylindrical shell, which is partially covered with circumferentially laid compliant layers and immersed in an infinite heavy fluid medium. The finite elastic shell is simply supported and extended by two semi-infinite rigid baffles. The motion of the shell is governed by Donnell's equation and the sound field in the exterior fluid medium satisfies Helmholtz's equation. The compliant layers are modeled using the locally reacting model with the thickness and mass effect of the layer being ignored. The fluid loading is calculated by using a recently developed FFT-based algorithm which can greatly reduce the time cost of computation. Combining the equations of motion of the shell, the four-pole parameters of the compliant layer, and the fluid loading coefficients, an analytical formulation is theoretically established for the shell-coating-fluid system. Solution to this coupling system is obtained by solving a set of algebraic equations. The convergence and effectiveness of the solution is examined. Effects of the stiffness and the coating area ratio of the layers are discussed. Moreover, the present results are compared with those for the longitudinally covered shell. It is found that the axisymmetry of the coatings has an effect on the radiated power of the partially covered shell. A comparison between the analytical results and the numerical results calculated by the in-house codes is also included.