Dynamics of vertical pipe in deep-ocean mining system

Abstract

A 3-D geometrical nonlinear model for the entire lift system of 1000-m sea trial system of China Ocean Mineral Resources R&D Association was established with finite element method. The model was utilized to analyze the dynamic characteristics of the vertical pipe under the influence of moving velocity, current direction and wave. The simulation results show that the axial stress is dominant on the vertical pipe, its maximum is located at the pipe top, all stresses are much less than the allowable value of the vertical pipe and joint; the heave motion leads to violent fluctuation of the force and stress, but a period of 8 s is not likely to resonate the present pipe; against the current, 0.50 m/s is the suggested moving velocity of the ship and miner, while along the current, the moving velocity can be slightly higher than 0.75 m/s.