Study On Mechanical Behaviors Of Deep Ocean Buoys And Energy Harvesters

With the development of human society,the demand for energy resources is also growing.The countries all over the world have also placed marine resources in a very high strategic position and are committed to the development and exploitation of marine resources.As one of the main ways of marine monitoring,marine data buoys are widely used in marine climate detection and disaster warning.In this paper,a small disc buoy is designed.Hydrodynamic analysis and tower structure strength analysis are carried out by hydrodynamic analysis software and finite element simulation.The stability and reliability under different working conditions are analyzed,and the safety of buoy design is analyzed.It can provide a reference for the safety and reliability of the buoy design.Wave energy is inexhaustible clean energy.Dielectric elastomer can convert mechanical energy into electrical energy.Based on this characteristic,a dielectric elastomer-based wave energy harvester is designed and installed on the buoy.The electric energy is supplied to the buoy,which provides a reference for the design of the buoy battery in the future.The main work and research results of this paper are as follows:(1)Analysis of marine environmental loads.According to Chinese offshore sea conditions,determine the limit work and ultimate living environment of the buoy.Introduce the basic calculation methods for wind,flow,wave load and wave spectrum.(2)Buoy hydrodynamic analysis.Analyze the initial stability of the 2.4 m disc buoy.The additional mass coefficient,damping coefficient and response amplitude operator RAO curve of the buoy are obtained by using the hydrodynamic software DNV SESAM.In the main energy frequency range of the wave,the RAO in the heave direction is basically maintained at 1,and the RAO in the roll direction is small,and the wave adaptability to different wave height and frequency is strong,and good stability can be ensured.(3)Strength analysis of the buoy tower structure.When encounter extreme sea conditions,the buoy may occur tower breakage,instrument damage,etc.In this paper,ABAQUS is used to simulate the buoy tower.According to the RAO curve of the motion frequency,the stress of the buoy tower under different working conditions is calculated,and analyze whether towers in extreme living conditions will be destroyed.The maximum stress of the buoy tower occurs at the junction with the pontoon.As the wave height and the wave frequency increase,the tower stress will gradually increase.(4)Design and research of energy harvesters.According to the characteristics that dielectric elastomer can convert mechanical energy into electrical energy,a dielectric elastomer-based energy harvester is designed to be vertically mounted on a buoy to convert the mechanical energy of the heave motion into electrical energy.Analyze the influence of the applied voltage,the mass of the vibrator and the aspect ratio of the dielectric elastomer film on the amplitude and period during the free vibration.Analyze the forced vibration under excitation outside the working environment.Considering the gravity,analyze the power generation of different pre-stretching lengths,if equipped with multiple energy harvesters at the same time,can generate power to meet the power demand of the buoy.In this paper,the hydrodynamic analysis and finite element simulation are used to analyze the motion characteristics of the buoy in the wave and the strength of the tower structure,and the energy harvester based on dielectric elastomer is designed to convert the wave energy into electric energy,which can theoretically meet the electricity demand of buoy.