Research On Finite Element Modeling Method For Submarine Cable Vibration Based On Optical Fiber Sensing

The optical fiber composite submarine cable is an important link that ensures the transmission and data communication between islands,offshore work platforms and offshore wind farms,and plays an important role in social and economic development.As the submarine cable is generally laid on the seabed or the seabed silt,due to the complicated seafloor topography,ocean currents and tidal erosion and other factors,wear,fatigue and other phenomena,affecting the normal submarine cable work.Based on the dynamic finite element method and finite element analysis software of ANSYS,the modeling method of submarine cable vibration under wave force is studied in this paper,which provides a theoretical basis for monitoring the working status of submarine cable with distributed optical fiber vibration sensing technology in accordance with.In this paper,the structure of the submarine cable is simplified according to the scene operating environment of the submarine cable and the material characteristics of each layer structure.The APDL language in the finite element software ANSYS is adopted to establish the twist by the helical sweep of the end section Laminated structure.Two different modeling methods are used in the finite element modeling of single-core submarine cable vibration.One is to use fluid-solid coupling mode to model the fluid domain and the solid domain separately,Interface force transmission,the fluid load is applied to the submarine cable to realize the ocean floor scouring effect of submarine cable vibration finite element analysis,this method can intuitively and accurately restore the submarine cable operating environment,but there are modeling complex,long calculation time,and the other is the method of direct application of wave force load.That is to say,the specific element type is selected and the wave force is directly assigned to the submarine cable body by the internal calculation program of ANSYS,without the way of exerting the force by establishing extra structure,which to a certain extent,the method reduces the calculation difficulty and calculation time.In addition,this paper also established a three-core submarine cable vibration model by applying wave force directly.Through the above finite element modeling and simulation,the stress and displacement data and the acceleration data of the light unit of the submarine cable under the action of wave forces are obtained.Based on the data,the position-stress curve is drawn,Time-acceleration curve and the amplitude-frequency curve.It provides a reference for studying the vibration characteristics of submarine cable under the action of wave force scour and judging the working status of the submarine cable.