Hydrodynamic Performance And Mooring Fatigue Analysis Of A New Type Of Floating Breakwater

Aquaculture technology has become the focus of today’s development as the lack of marine fishery resources.More and more aquaculture cages have appeared in the offshore open sea area,but the cage with flexible structure is easy to cause damage under the impact of waves.The manufacturing and installation of floating breakwater plays a key role in improving the safety of aquaculture cage and ensuring the normal growth of aquaculture fish.At the same time,marine aquaculture technology is becoming more and more intelligent and automatic so that the aquaculture equipments need enough electric energy.Therefore,a new type of floating breakwater system is applied in this paper,which is composed of double pontoon floating structure,tidal current energy capture structure with Savonius blade and mooring system.The hydrodynamic performance of the system is analyzed from two aspects on numerical calculation and experimental research.The long-term reliability of breakwater system is also considered to the fatigue analysis of its mooring system.the major works of this paper are done as follows:Firstly,the floating body,tidal current energy capture paddle structure and mooring structure of the new type breakwater system are designed,the preliminary scheme and design index of the breakwater system are obtained.The numerical theories including wave attenuation,time-domain hydrodynamic equation and mooring load calculation of the floating breakwater are studied.The numerical theory is modified and improved according to the influence of Savonius blades.Secondly,the hydrodynamic model and the finite element model of the breakwater are established by the AQWA and APDL respectively.The numerical simulation of the model is carried out by using AQWA hydrodynamic solution program.The motion response,wave dissipation performance and mooring load response results of the new type of paddle breakwater and the double pontoon breakwater without paddle are compared and analyzed.At the same time,three key geometric parameters are studied for the hydrodynamic performance of the new type of breakwater.Thirdly,the experimental model of the breakwater and test system are established,and the regular wave test research is carried out from two aspects of wave dissipation performance and mooring tension response to verify the results of periodic influence and geometric parameters influence.Finally,the distribution of the tension range of the new breakwater mooring system under long-term random wave loads is analyzed.According to the characteristics of the wide-band tension distribution,a BP artificial neural network for fatigue damage prediction is applied in this paper,and the model is optimized on its parameters and trained under MATLAB.The fatigue damage prediction results acquired by artificial neural network are analyzed and compared with results of hydrodynamic calculation based on T-N curve and P-M cumulative fatigue rule.