HULL STRUCTURAL STRENGTH EVALUATION BASED ON FIBER BRAGG GRATINGS PRESSURE SENSORS TO MEASURE SPATIAL PRESSURE DISTRIBUTION ON SHIP'S HULL IN WAVES

摘要

In this study, the feasibility of Fiber Bragg Gratings (FBG) pressure sensors is verified for hull structural strength evaluation. To investigate the effectiveness of FBG pressure sensors for the strength evaluation, the towing tank test is carried out with a pure hydro-structural (PHS) ship model, which is capable of elastic deformation. FBG pressure sensors are installed on the outer hull surface and FBG strain sensors are installed inside the hull to calculate a vertical bending moment (VBM). Measured water pressure is interpolated on the whole hull surface by using the weighted average approach based on relative distance. Finite Element Analysis (FEA) is carried out based on interpolated water pressure. In FEA. inertia force is considered according to the inertia relief method, and VBM is calculated by FEA results. The strain measured by FBG strain sensors is transformed to VBM based on the calibration coefficient obtained by the vertical bending test. Finally, VBM obtained by the measured water pressure and strain are compared. As a result. VBM obtained by the measured water pressure is consistent with ones obtained by the measured strain. Therefore, the availability of water pressure measured by the FBG pressure sensors is validated for the hull structural strength evaluation in terms of VBM.