Structural-Acoustic Coupling Analysis Based On Hybrid Finite Element-Wave Based Method

The internal acoustic problems of closed acoustic cavities are of great significance in practical engineering problems,such as the inner space of vehicle,aircraft cabin,the inner space of submarine and ship cabin.Establishing the prediction model of such structure-acoustic coupling system and analyze sound pressure inside the cavity can provide guidance for noise reduction.At present,there is a lack of deterministic numerical analysis method for mid frequency acoustics analysis of structural-acoustic coupling systems.The FEM(Finite Element Method)has the characteristics of geometric adaptability,but low computational efficiency with the increase of the analysis frequency,while the WBM(Wave Based Method)has the properties of high convergence rate but poor geometric flexibility.Combining the advantages of finite element method and the wave based method can increase the prediction frequency,and ensure the geometric adaptability of the modeling method at the same time.The hybrid FE-WBM can be used to deal with the mid frequency prediction analysis.Establishing the WBM model of flat plate and wedge-shaped cavity,the field variable distribution,the frequency response curve at the response point and the error distribution are compared with the FEM to show the accuracy of the WBM.Taking the system matrix dimension of the model and the running time of the CPU as independent variables respectively,while the relative error of response point as dependent variables,the convergence of plate structure at certain frequency is analyzed to compare the computational efficiency of FEM and WBM.The sufficient and necessary condition for the convergence of the WBM is that the solution domain must be convex.If the solution domain is non-convex,it needs to be divided into convex regions which do not overlap each other and realize the coupling between subdomains by continuity condition.The multi-domain numerical model of L-shaped plate and L-shaped cavity are established by WBM respectively to show the validity of the domain decomposition,and that the application range of WBM can be extended.The FE-WBM model,which can reduce the error caused by the discrete element,improve the predictable frequency of the model,and further expand the application of WBM,is established by applying the FEM for complex geometry and the WBM for the remaining parts.Taking a 2D vehicle interior as an acoustic example,the sound pressure prediction model is established by FE-WBM in Mat lab.The prediction results are compared with the finite element method to verify the accuracy of the hybrid modeling method.The convergence of FE-WBM is shown by the convergence analysis at specific frequencies.Taking two structural-acoustic systems with cuboid cavity and non-convex acoustic domain as example to show the modeling method of the structural FEMacoustic WBM and the structural FEM-acoustic with FEM and WBM respectively,and all the programs are written in Mat lab.An experimental model of structure-acoustic coupling system is designed.The sound pressure prediction model of the experimental model is established by using the WBM and the FE-WBM.The prediction results are compared with the experimental results to prove the validity of WBM and FE-WBM in structural-acoustic coupling system analysis.