FEM model built in ANSYS is used to simulate deep-ocean mining pipe. A 3-D nonlinear pipe element model, including vertical pipe, pump, buffer and flexible riser, is established. The model is utilized to analyze the vertical pipe of COMRA's 1000-m sea trial system. First, the static configuration and stress are calculated, and then by modal analysis, it is found that the first ten mode frequencies of the lift system are far below the wave frequency in operational situation. The transient responses of the present vertical pipe to the moving ship with horizontal and vertical excitations have been simulated too.


Connecting the miner to the ship, the configuration, stress and dynamic response of the lift pipe system are significant to the design, control and safety of practical mining system. Chung (1980; 1981; 1994; etc) has studied the 4000-ft and 18000-ft vertical pipe in detail on the assumption that the pipe bottom be free or pinned to the miner. The 1000-m sea trial system of China Ocean Mineral Resources R&D Association (COMRA) is consisted of mining ship, vertical pipe, pump, buffer, flexible riser and self-propelled miner (Liu, 2003). We focus our attention on the simulation of the vertical pipe movement (together with the pump and buffer) in this paper. Affected by the motions of the ship and miner, the interaction between the buffer and flexible riser has direct influence on the configuration and stress of the vertical pipe. Therefore, based on the deep-ocean mining systems and integrated control of the ship-pipe-buffer-flexible hose and self-propelling miner one of which was tested in 1976 and 1978 in the North Pacific Ocean research of Brink and Chung, 1981 and Chung (1980; 1981; 1994; 1999; etc), we model the whole lift system (including the vertical pipe, pump, buffer and flexible riser) in this simulation.

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