Dynamic Analysis Of ROV Deep Ocean Mining System

The development of deep-sea mining technology plays an important role in the development of society and economy and the national resources security.A new-type ROV(Remote Operated Vehicle)deep-sea mining system is proposed for solving existed problems in the deep-sea mining system which is under research at present.This paper is based on the 1000m ROV deep-sea mining system,uses the finite element method and ANSYS Workbench software and synthesizes various complex loads(such as gravity,buoyancy,wave force,current force,etc.)on the lifting system(lifting pipe and transporting pipe).This paper analyzed the effects of fluid-structure interaction and the different responses of lifting pipe and flexible transporting pipe to different factors(such as velocity of internal flow,density of internal flow,velocity of outflow,etc.).The main contents of this paper are as follows.(1)The overall scheme of 1000m ROV deep-sea mining and the parameters of each part of the system and the environmental parameters of deep sea were given.(2)External loads of lifting pipeline were introduced.With Morison equation,the wave force and current force of lifting pipeline were calculated.Detailed stress analysis for every part of the lifting pipeline was made.(3)Based on the principle of fluid-structure interaction,this thesis solved the analysis process of one-way and two-way fluid-structure interaction with ANSYS Workbench and established the three-dimensional finite element model about lifting pipe,internal flow and external flow for the fluid-structure interaction analysis.From the analysis results,we realized that different responses of the maximum principal stress and the maximum lateral displacement of the lifting pipe will be caused by different factors(such as different sea conditions,velocity of internal flow,density of internal flow,velocity of outflow and the towing speed,etc.).(4)The dynamic equation of fluid-solid interaction was presented,which is functioned by the flexible transporting pipe,the internal flow and the external flow.Then the three-dimensional finite element model was established about flexible transporting pipe,internal flow and external flow,which is used for the fluid-structure interaction analysis.We realized that different responses of the maximum principal stress,the maximum lateral displacement and the maximum transversal displacement of the flexible transporting pipe will be caused by different factors(such as velocity of internal flow,density of internal flow,velocity of outflow,etc.).