Vibration and acoustic waves of multilayered cylindrical shells carrying internal components attached by nonlinear compliant mounts

Abstract

The structural-acoustic interactions of a coupled multilayered composite cylindrical shell and internal equipment system immersed in an infinite fluid medium are analyzed. The internal equipment is installed on the cylindrical shell by a series of nonlinear compliant mounts, which are represented by nonlinear springs and linear viscous dampers. Both the translational and rotational vibrations of the internal equipment are considered, and they are strongly coupled together due to the nonlinear elastic mounts. The nonlinear dynamics model of the coupled cylindrical shell and internal equipment system is established using a modified variational method, and the fluid exterior to the shell is modeled by a time-domain boundary element method. A strongly coupled serially staggered procedure is adopted to solve the governing equations of the structural system and the acoustic fluid as a coupled system. The results of the present analysis are validated by comparing with those obtained from the finite element method. The nonlinear structural vibration and acoustic wave behaviors of the coupled system containing compliant mounts with linear or nonlinear stiffnesses (including quadratic, cubic, quartic, quadratic-quartic types of stiffness) are analyzed. The effects of the translational and rotational motions of the internal equipment as well as their coupling on the nonlinear vibration and acoustic wave responses of the coupled system are examined. Physical insights into the super-harmonics in the vibration and sound pressure responses of the coupled system are provided.