The Research On Topology And Acoustic Radiation Characteristics Of Stiffened Plate

Thin plate is a commonly used structural part and play an important role in military and civil fields, but characteristics of the thin plate is not good enough. Adding thickness or applying stiffener may improve mechanical and acoustic performance of the thin plate. However,the thin plate increases selfweight by adding its thickness and has not high utilization of materials. So adding stiffener on the thin plate is a optimum method because of not increasing its weight. The stiffened plate structure can meet the requirements of structural strength,structural stiffness,structural stability and acoustic characteristics by adjusting size and distance of stiffener in engineering design, so it is widely used in military and civil fields. Mechanical performances and acoustic radiation problems of the stiffened plate caused researchers great interest early. Many scholars reseached its bearing capacity, maximum intensity, stability and acoustic radiation performances at home and abroad. Based on topology and shape of stiffener plate, a specific study on stiffness and acoustic radiation of the stiffened plate which may alter as the topology/shape and boundary conditions changed was completed in this paper.This paper took commonly used stiffened plate as the research object. Based on Mindlin plate theory, spatial beam theory and methods of physical model simplify, a accurate finite element model of the stiffened plate was set up by four nodes shell element and two nodes beam element. Then the model was checked calculation for back-analysis of topology/shape and acoustic radiation of structure. In the end,a analysis process about sound radiation of vibrating structure was designed according to mechanism of sound radiation and theory of acoustic radiation from the thin plate in this paper.By taking first-order natural frequency of the stiffened plate as target, a specific discussion was finished by changing structure parameter,types or distribution of stiffeners and boundary conditions for effects of first-order natural frequency of the stiffened plate. Then according to natural frequency value evaluated the stiffness characteristics of the stiffend plate. This discussion drawed useful conclusions and provided theoretical basis for back-analysis of acoustic radiation of the vibrating stiffened plate. This paper also designed a example of structural sensitivity analysis. By taking structure parameters of the plate and the beam as design variables, the paper studied the eigenvalue sensitivity and displacement sensitivity of the stiffened plate. This pointed out the direction for structural topology optimization of the stiffened plate. This paper designed a calculation model about acoustic radiation of vibrating structure in infinite baffle on the basis of the flexible structure vibration equation and boundary element coupling calculation equation. Then combination of finite and boundry element methods, it discussed structure parameters of plate and stiffener, types or distribution of the stiffener, location of the force incentive, length to wide ratio and structure damping and so on for influence of sound radiation efficiency, acoustic power and radiation directivity. This discussion drawed some useful conclusions and provided theoretical basis for structural-acoustic optimization of the stiffened plate.