# Underwater Radiated Noise Prediction Method of Cabin Structures under Hybrid Excitation
###### Abstract  
Aiming at the engineering limitations of traditional ship vibration online monitoring and noise prediction methods, this paper proposes a method for online monitoring and underwater radiation noise prediction of cabin structures' vibration and noise under hybrid excitation of sound and force. The method first constructs the condition test model; based on OTPA technology, the \"acoustic-vibration\" transfer function between sound and vibration monitoring points in the cabin and the \"acoustic/vibration-acoustic\" transmission network inside and outside the cabin structure are obtained. Secondly, based on the \"acoustic-vibration\" transfer function, the online vibration and sound monitoring data are decoupled and processed to obtain the modified vibration and sound monitoring data. Finally, the near-field radiation noise on the conformal hologram surface outside the cabin is predicted based on the \"acoustic/vibration-acoustic\" transmission network, and the far-field radiation noise of the cabin structure is predicted by the wave superposition method. In this paper, the contribution law of external radiation noise and the coupling characteristics of the monitoring information under the hybrid excitation of sound and force are analyzed theoretically, and the decoupling method of coupling information is also studied. This method makes up for the problem of missing underwater radiation noise caused by sound excitation in traditional vibration monitoring, and it can effectively improve the prediction accuracy of underwater radiation noise. The effectiveness of the method is further verified by the tank model experiments. hybrid excitation; vibration and acoustic monitoring; wave superposition method; radiated noise prediction +
Footnote †: journal: Applied Sciences  
superposition method (ERSM), and wave superposition method (WSM). The FEM [4; 5; 6] can effectively calculate the acoustic radiation of any structure by modeling the radiator. It transforms continuous problems into discrete problems and solves the system equations. However, the amount of calculation increases rapidly with the increase in the frequency and physical field size. On the basis of the FEM, the BEM [7; 8; 9] transplants the concept of solving the discrete elements of the domain division into the boundary integral equation, reducing the computational load to a certain extent, but still cannot be solved quickly. In addition, singular integral problems are prone to occurring at the structure boundary. OTPA can obtain the transfer function of \"monitoring point-target point\" through condition testing, and then predict the response of the target point under any condition [10; 11; 12]. However, the target point of this method is fixed during the working condition test, and it cannot calculate the radiated noise at any position except the target point, so there are some limitations in its practical application [11; 13; 14]. The ERSM divides the surface of the radiator into several piston units and considers the superposition of the radiation sound field of each piston as the total radiation sound field of the radiator [15; 16; 17]. However, this method only monitors the vibrational information of the radiator shell, and there are shortcomings in predicting the radiation noise caused by sound transmission in some frequency bands, which will lead to large prediction errors and require more vibration monitoring points, and the test system is complex. In the 1990s, [PERSON] et al. proposed the wave superposition method based on the superposition integral equation [18; 19]; subsequently, a large number of scholars conducted in-depth studies on this method [20; 21; 22]. In order to solve the engineering limitations of traditional ship vibration online monitoring and noise prediction methods, a method of underwater radiation noise prediction for cabin structures based on the synchronous monitoring of vibration and sound is proposed in this paper.