STEADY-STATE RESPONSE OF ACOUSTIC CAVITIES BOUNDED BY PIEZOELECTRIC COMPOSITE SHELL STRUCTURES

Abstract

A formulation to calculate the coupled response of composite shells with embedded piezoelectric layers and an enclosed acoustic fluid is presented in this paper. The methodology consists of three parts: (1) a formulation for the electro-mechanical response of piezoelectric shells; (2) a formulation for the three-dimensional acoustic response of the enclosed fluid; and (3) the combination of the formulations (1) and (2) to calculate the coupled smart structure-acoustic fluid response. A recently developed mixed field laminate theory is adapted for the analysis of piezoelectric shells. The theory combines the first order shear theory kinematic assumptions with a layer-wise approximation for the electric potential. Shell geometry is described in an orthogonal curvilinear co-ordinate system and general piezoelectric material descriptions and laminate configurations are considered. A boundary element formulation is developed to calculate the acoustic response of the enclosed fluid. Quadratic conforming boundary elements are used to discretize the fluid boundary. Advanced numerical integration techniques are employed to calculate singular elements in boundary element matrices. The treatment of distributed acoustic sources is also presented. A formulation to calculate the coupled fluid-structure response is also developed. Relations between the structural and acoustic variable on the structure-fluid interface are utilized to generate the coupled system of equations in terms of the kinematic shell variables and acoustic pressures on the fluid boundary. The convergence of the present developments is established by studying a circular cylindrical shell with an attached piezoelectric layer. The coupled response is investigated for various types of mechanical loads and active voltage patterns.