基于声散射波的水下声固耦合系统频率识别方法

Frequency Identification Method of Underwater Acoustic-solid Coupling System Based on Acoustic Scattering Wave

目的面向水下声固耦合系统固有频率识别需求,提出了一种基于水下声压响应的系统特征频率识别方法。方法利用有限元法计算得到无限水域中结构的时域散射声压,采用希尔伯特-黄变换(HHT)方法识别了声散射波中各阶模态分量中的特征频率。针对传统的HHT方法在经验模态分解(EMD)步骤中存在产生虚假模态和模态混叠的情况,应用相关系数检验的方法剔除虚假模态分量,并利用频谱分析与滤波技术相结合的方法避免模态混叠的影响,提升识别结果的精度。结果基于该方法识别了水下圆柱、平板等声固耦合系统的固有频率,验证了该方法的适用性。结论该方法能有效识别声固耦合系统的主要固有频率。

The work aims to propose a natural frequency identification method based on submerged structural scattered sound pressure response to meet the requirement of natural frequency identification of submerged acoustic-structure coupling systems.The time-domain scattered sound pressure of the structure submerged in infinite water was calculated by the finite element method,and the characteristic frequency of each modal component in the acoustic scattered wave was identified by Hilbert-Huang transform.In view of the existence of false modes and mode aliasing in the empirical mode decomposition(EMD)step of the traditional HHT method,the correlation coefficient test method was applied to eliminate false mode components,and the combination of spectrum analysis and filtering technology was used to avoid the influence of mode aliasing,which improved the accuracy of HHT method in identifying the natural frequencies of submerged structures.Based on the method,the natural frequency of the system such as submerged cylindrical shell and slab was identified,which verified the accuracy of the method.The identification results show that the proposed method can effectively identify the main natural frequencies of the acoustic-solid coupling system.