| As an important equipment for marine resources exploration,underwater information acquisition and ocean military operations,underwater vehicle plays an important role in the field of national defense.In order to accomplish these tasks,there are high requirements for its underwater acoustic stealth performance.In recent years,with the development of sonar detection technology,this requirement is increasing,so it is necessary to improve the realtime monitoring and evaluation ability of underwater vehicle radiated noise.In addition,the application of composite materials in underwater vehicles is increasing,and the analysis and optimization of vibration and radiated noise are very important.In order to solve the problem of real-time monitoring and prediction of acoustic radiation,based on the finite element coupled infinite element method and Kirchhoff near field method,a fast prediction method of acoustic radiation in full frequency band for underwater structures is studied in this paper.In this paper,using the secondary development interface of finite element software Abaqus and programming with Python,the placement of vibration sensors on the surface of the research object is discussed.The influence of the placement spacing of vibration sampling points on the accuracy of acoustic radiation prediction is simulated and analyzed in the software,and a set of ideas for selecting vibration measuring points are summarized,The influence of stiffener structure on the selection of vibration sensor is also discussed.In addition,the applicability of the fast prediction method of acoustic radiation and the selection idea of vibration sensor in composite structure is also studied.Finally,considering the possible lack of vibration measurement points in engineering application,through the comparative study of a variety of schemes,the influence of the missing number and location of vibration sensors on the prediction accuracy of acoustic radiation is discussed.In addition,in order to optimize the radiated noise of composites and improve their low-frequency acoustic performance,a layer by layer optimization method for laminated angle of composite laminates is presented by using finite element software Abaqus and numerical optimization software Isight.After that,the influence of increasing the thickness and position of the damping layer on the radiated sound power of the composite is discussed.The results show that the optimization strategy proposed in this paper is accurate and effective.The peak of low frequency acoustic radiation spectrum of the optimized structure shifts to high frequency,and the number of peaks is significantly reduced.In addition,the effect of adding damping layer on low frequency acoustic radiation is discussed.The research work in this paper can be used for reference to the real-time monitoring and prediction of radiated noise of underwater vehicle structure and the arrangement of vibration sensors in engineering.At the same time,the layer by layer optimization method and vibration and noise reduction strategy proposed in this paper can be used for reference to improve the low-frequency acoustic performance of composite structures. |
