Propeller's operational modal parameters identification based on Fiber Bragg Grating sensing

The propeller will generate a lot of harmful vibration and noise underwater. In order to effectively solve the problem of vibration and noise, it is of great significance to accurately obtain the modal parameters of propeller for the design and optimization of the propeller structure. Since it is difficult to measure the load of propeller when it is running underwater, only operational modal analysis (OMA) method can be used to identify the operational modal parameters of propeller. This paper is aimed at solving this problem by taking the metal propeller as the research object, an open-water test platform was built, and the Fiber Bragg Grating (FBG) sensors were used to obtain the underwater strain information of the propeller. Finally, the operational modal parameters of propeller are identified by the Stochastic subspace identification (SSI) method. In addition, the modal simulation analysis of propeller was carried out by using finite element simulation software, and the experimental results were compared with the simulation results. The results show that the stochastic subspace identification method can accurately identify the operational modal parameters of propeller. •In this paper, a contact measurement method based on Fiber Bragg Grating(FBG) Sensing is used to monitor the underwater operation status of the propeller.•Using the Stochastic Subspace Identification method, after removing the harmonic modes by half-power spectral matrix, the operational modal parameters were identified more accurately.•A propeller underwater monitoring system and open-water test platform were designed based on Fiber Bragg Grating sensing network.•The comparison errors are within 15% proves that it is feasible to identify the operational modal parameters of the underwater propeller by Stochastic Subspace Identification method based on the FBG sensing network.