Sound Radiation And Topology Optimization Of Plates With Elastic Boundary Research And Application

With the increasing of people’s living level, the requirements of the quality of life arealso increasing and the noise pollution has become increasingly outstanding. The vibration ofstructure produces noise and the vibration is propagated by the structure and causes thevibration and acoustic radiation of the outer surface. Previous research of vibration and noiseusually establishes the boundary conditions with clamped or simply supported. However, inthe thesis the boundary conditions are established with elastic boundary, it’s more coincidentwith the real situations. Topology optimization method as mature optimization algorithm, hasbeen applied in the field of structure vibration and noise reduction. This thesis investigates theelastic boundary plate structure topology optimization, and applies the optimized structure inthe structure’s vibration and noise reduction. It provides a new way for structure’s vibrationand noise reduction design.Firstly, the structure supple degree and the first order natural frequency are used as theoptimization objective. The topology optimization analysis of the elastic boundary platestructure is carried out. The influence of topology form is studied with different stiffnessconditions and the response pattern is obtained. Secondly, the stiffeners are attached to theplate, according to the topology optimization form and compared to other forms. The acousticresponse of plate with stiffeners is calculated to verify the sound pressure level reduction. Theinfluence of acoustic radiation is studied with different structure boundary stiffness andstiffener form. Thirdly, the damping layers are attached to the plate, according to the topologyoptimization form and the modal damping ratio of the structure are calculated. The influenceof modal damping ratio is studied with different damping layer layout and stiffness conditions.The acoustic response of plate with damping layer is calculated to verify the sound pressurelevel reduction. Fourthly, the research of elastic boundary is applied to the design of noisereduction of gear box, and the panel contribution of the gear box is calculated. The panelswhich give the greatest contribution to the sound pressure are selected to do topologyoptimization calculation, and according to the topology form, the stiffeners and damping layerare attached to the plate. The acoustic response of gear box with stiffeners and damping layeris calculated to verify the sound pressure level reduction.Through calculation and analysis, it is proved that the topology optimization has application value in vibration and noise reduction design. The stiffness of elastic boundaryhas significant effect on the acoustic response of structure, and the noise reduction designscheme of gear box is obtained.