VIBRATION AND LOW-FREQUENCY ACOUSTIC ANALYSIS OF PIECEWISE-ACTIVATED ADAPTIVE COMPOSITE PANELS

This paper presents an analytical modeling technique which uses the Ritz method, classical laminated plate theory, and finite panel acoustic radiation theory to predict the modal and structural acoustic behavior of locally activated shape memory alloy hybrid composite panels. This technique for performing a spatial integral within the Ritz approximation of the laminated plates with nonlinear material properties can also be applied to analysis of laminated plates with stiffeners and other spatially nonlinear characteristics. The application of interest for this presentation is structural analysis of laminated plates. However, this technique may also be used for analyzing plates with ribs and stiffeners, etc. By minimizing the total energy functional, integrating piece-wise over discrete homogeneous panel regions characterized as activated and unactivated and summing these integrals over the total panel area; stiffness matrices are found to determine natural frequencies, mode shapes and steady-state dynamic response to periodic incident plane wave acoustic excitation. This information is then used to determine the structural acoustic response as a function of frequency for a laminated plate with material nonlinearities. Analytical results are presented for balanced symmetric adaptive panels to demonstrate how various localized activation scenarios affect modal and structural acoustic behavior.