Vibroacoustic Analysis And Damping Treatment Optimizarion Of Stiffened Structures With Discrete Non-uniform Edge Restricts

Lightweight plate and shell structures are of important engineeringcomponents utilized extensively in vehicle engineering and defenseequipment et al. Environmental disturbance, working loads or bypassedforces, excite the thin-walled structures to vibrate and radiate noiseoutward the external environment and into the internal cavities,subsequently the vibration may cause structural fatigue and at the sametime the radiated noise seriously affect the comfort of passengers. With thedevelopment of advanced joining technologies, those lightweightstructures are often non-uniformly connected along the contours, as likethe case of point welding, riveting and gluing, et al. Also, passive dampingtreatment means for vibration and noise control have already been widelyapplied in engineering. Constraint layer damping (CLD) treatment, as aneconomic countermeasure has been simple in implementation but veryeffective in vibration/noise control. Due to the complexity of boundaryconditions, further investigations have to be conducted on the optimalutility of CLD technique for the vibration suppression and noise radiationreduction of those non-uniformly bounded plates/shells.This dissertation presents a study on the vibro-acoustics and CLDtreatment optimization for vibration of and sound radiation fromplates/shells with non-uniform boundary conditions (BCs). The equationsof motion are first derived by using energy approach for the vibratingplates and the corresponding stiffened structures, with added CLD patchesadhered and non-uniform edge restricts. The transformation formulation is then put forward to map arbitrary quadrangular shapes into rectangularones, which enables the analysis of the vibro-acoustics of arbitraryquadrilateral plates with the approach developed for rectangular plates.Following the presented approach, the vibro-acoustic analysis is performedusing Rayleigh-Ritz method for the non-uniformly supported rectangularplates and then the stiffened ones. GA-SQP method is applied to search forthe optimal configuration of CLDs in minimizing the vibration and soundradiation of the considered plates and stiffened ones with continuous ornon-uniform BCs under various excitation conditions. The optimizationresults are schematically presented and discussed.The work within this investigation helps to an in-depth recognition ofthe vibro-acoustic properties of plates/shells with complex BCs, and theobtained results are meaningful to engineering application of CLDtreatments for vibration/noise control of the studied lightweight structures.