The control of decentralized velocity feedback on curved aircraft plates under turbulent boundary layer excitations is numerically investigated in this paper. Sixteen active control units are set on the plate to reduce the vibration and sound radiation of the plate. The computational results from the two methods are compared to verify the accuracy of the numerical model. The plate kinetic energy and the radiated sound power under turbulent boundary layer and control unit excitations are analyzed. The influences of control unit distribution, plate thickness and curvature on radiated sound are discussed. Unlike a flat plate, the control of the lower-order high radiation modes of a curved plate under TBL excitations is critical since these modes predominate the sound radiations. The control of these modes, however, is sensitive to the ratio of the stiffness associated with the membrane tensions to the stiffness associated with the bending forces. This ratio implies that the plate curvature and the thickness play an important role in the control effect. When the plate is thinner and the radius is smaller, the control is less effective.
The effect of perforating the honeycomb walls of a honeycomb sandwich panel on the dynamic bending stiffness and sound transmission loss of the panel is investigated. The dynamic bending stiffness and sound transmission loss of several sandwich panels with different cores are calculated using a semi-analytical method, and the static bending stiffness and flatwise stiffness of these structures are also analyzed with the finite element method. Furthermore, the influences of the honeycomb shape, the hole shape of the perforated honeycomb wall, the number of perforations, and the wall thickness on the vibro-acoustic and mechanical properties of the sandwich panel are investigated. The results show that the static mechanical performance of the sandwich panel quickly reaches a high level when the ratio of honeycomb wall thickness to length t/ l is about 5.3 × 10−3 and a square hole in the honeycomb wall can bring superior characteristics of “high static and low dynamic properties,” significantly improving the sound insulation of the sandwich panel. This study makes an effective reference for the optimized design of the innovative sandwich structure in practical applications.
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