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The anisoparametric three-node MIN6 shallow shell element is extended for modeling Macro-Fiber Composite/Active Fiber Composites (MFCTM/AFC) actuators for active vibration and acoustic control of curved and flat panels. The recently developed MFCTM/AFC actuators exhibit enhanced performance, they are anisotropic and highly conformable as compared to the traditional monolithic isotropic piezoceramic actuators. The extended MIN6 shell element includes embedded or surface bonded MFCTM/AFC laminae. The fully coupled electrical-structural formulation is general and it is able to handle arbitrary doubly curved laminated composite and isotropic shell structures. A square and a triangular cantilever isotropic plates are modeled using the MIN6 elements to demonstrate the anisotropic actuation of a surface bonded MFCTM actuator for coupled bending and twisting plate motions. Steady state modal bending and twisting amplitudes of the cantilever square and triangular plates with MFCTM actuator are compared with the plate’s steady state modal amplitudes with traditional PZT 5A actuator for different angle orientations. Frequency Response Functions (FRF) for the square plate with MFCTM and PZT 5A actuators are also obtained and their actuation performance is compared. The actuation performance of the MFCTM at different locations is also investigated.

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Considerable attention has been devoted to actively and passively controlling the sound radiation from vibrating plates into closed cavities. With the advent of smart materials, extensive effort has been exerted to control the vibration and sound radiation from flexible plates using smart sensors/actuators. The Active Constrained Layer Damping (ACLD) treatment has been used successfully for controlling the vibration of various flexible structures. The treatment provides an effective means for augmenting the simplicity and reliability of passive damping with the low weight and high efficiency of active controls to attain high damping characteristics over broad frequency bands. This study investigates a numerically simulated example consisting of an ACLD treated plate/acoustic cavity system excited by a point harmonic force. In this study, an ACLD treated plate/acoustic cavity coupled finite element model is utilized to calculate the structural intensity and sound pressure radiated by the vibrating plates. In the passive control, the optimum placement of ACLD patches is determined by the structural intensity of ACLD treated plates and compared to the results obtained by using the strain energy approach. The influence on the structural intensity of the plate due to the damping treatment is investigated.

In the extensive published literature on panel flutter, a large number of papers are dedicated to investigation o f flat plates in the supersonic flow regime. Very few authors have extended their work to flutter o f curved panels. The curved geometry generates a pre-flutter behavior, triggering a static deflection due to a static aerodynamic load (SAL) over the panel as well as dynamic characteristics unique to this geometry. The purpose o f this dissertation is to provide new insights in the subject o f flutter o f curved panels. Finite element frequency and time domain methods are developed to predict the pre/post flutter responses and the flutter onset o f curved panels under a yaw flow angle. The first-order shear deformation theory, the Marguerre plate theory, the von Karman large deflection theory, and the quasi-steady first-order piston theory appended with SAL are used in the formulation. The principle o f virtual work is applied to develop the equations o f motion o f the fluttering system in structural node degrees o f freedom. In the frequency domain method, the Newton-Raphson method is used to determine the panel static deflection i Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.