Dynamic Interactions of a Pipe System With a Seafloor Miner for Deep-Ocean Hardrock Mining

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9531182 Chung Present theory is based on incorporating a new concept of vertical pipe connecting to a miner and application of external (control) force on the pipe for the control of pipe- miner motions. Modeling of an entire pipe-miner system pin-joins a horizontal pipe to the long, near-vertical pipe system and to a self-propelling seafloor miner. The elastic joints along the pipe can be made effective in changing the axial, as well as, bending characteristics. To apply external (control) forces to the joints for the control of the lateral motion of the pipe, the flexible joints will be modeled by finite element (FEM), as well as combined (rigid body) element (RBE). The accuracy and advantages of the two methods will be compared. The pin joint leads the entire system to zero eigenvalue and rigid mode, and the weight, as the inner axial force of the vertical pipe, further influences the eigenvalues of the entire system. A shift technique will solve this problem. The proposed 3-D nonlinear coupled responses with nonlinear axial dampers installed at the joints will reduce the axial stress and also influence the bending and torsion, as well. Soil (sediment) resistance for the miner will be modeled by both DEM (discrete elements) and FEM. The DEM modeling will use a mass of discrete particles of general geometry. Preliminary modeling of soil particles indicates that DEM modeling is very promising to examine micromechanical details of the soil particles. ***