Acoustic Enhancement Using Chemistry to Formulate
a Spray-On Constrained Layer Vibration Damper
Maintaining or improving acoustic and vibration quality of vehicles, the automotive industry continually faces design goals to reduce weight and manufacturing cost. In light of these objectives, advanced material design techniques facilitate the development of a high-performance, bulk-applied constrained layer vibration damper aimed at improved automotive acoustics.
The overall vehicle acoustic and vibration quality relies heavily on floor pan vibration dampers. A review of current industry damping technologies is addressed. Industry migration to bulk-applied extensional dampers from the once ubiquitous asphalt sheet damper is discussed. Furthermore, this paper addresses the development of a new bulk-applied constrained layer damper technology that delivers superior acoustical performance. The paper presents the chemistry formulation, the prediction of analytical results, and experimental validation.
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Comparison of experiments with finite element analysis
of plates with piezoelectric sensors/actuators
A finite element formulation is developed, including the fully coupled electrical-structural constitutive relations. An effort has been made to develop the most-general formulation applicable to laminated composite plates with inclusion of piezoceramic sensors/actuators. To this end, the von Karman large deflection theory was included, due to the results obtained from the experiments conducted. Solution of the large deflection problem led to an electrical-structural coupled tangent stiffness, which is believed to be the first time reported in the literature.
This paper presents comparison of the finite element simulation to experimental results for both static and dynamic piezoceramic sensors, in addition to dynamic piezoceramic actuation.
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Finite Element Modeling of MFC/AFC Actuators and Performance of MFC
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.
Piezoceramic actuator placement for structural acoustic and vibration control
of flat and curved panels
Piezoceramic actuator placement is investigated to minimize structurally radiated noise of flat and curved panels subjected to a uniform random acoustic disturbance. The flat panels use traditional PZT actuators, while the curved panels incorporate anisotropic macro fiber composite (MFC) PZT actuators. A linear quadratic regulator (LQR) feedback control augmented with acoustic radiation filters is used to minimize the radiated noise. A coupled finite element model is used in conjunction with a genetic algorithm to determine the optimum actuator location for two PZT actuators. Experiments are conducted to verify analytical simulation results.
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