ABSTRACT:

Interaction of fluid-solid coupled flexible hose and mining machine in a 1000m deep-ocean mining system is studied based on nonlinear finite element method with fluid-solid coupling model. Effect of the walking paths (e.g. line, circle and square) and walking velocities of the mining machine on the space configuration, support restrained force and maximum tensile stress of the flexible hose is investigated in order to provide guidance for the deep-ocean mining operation. Results show that the line walking of the mining machine is better for small lateral displacement, maximum tensile stress and support constrained force of the flexible hose than the circle and square walking. The walking velocities of the mining machine should be limited to an appropriate range (about 0.2–0.4m/s when the lifted speed of inner fluid is 4m/s) for the safety and efficiency of the mining operation.

INTRODUCTION

Popular deep-ocean mining system is usually composed of mining ship, rigid pipe, buffer, flexible hose and mining machine. On the one hand, walking performance of the mining machine is strongly influenced by the flexible hose, which is subjected to itself gravity, buoyancy of seawater, buoyancy of buoy, and action of current, wave and inner fluid. On the other hand, the walking path and velocity of the mining machine greatly affect the dynamic characteristics of the flexible hose, which is directly related to safety of the flexible hose and efficiency of the mining operation. It is of importance and significance to study the interaction of fluid-solid coupled flexible hose and mining machine in order to provide guidance for the deep-ocean mining operation. Currently, the flexible hose of high nonlinearity is mainly studied by finite element method (Owen, 1986; Vogel, 1987), finite difference method (Brown, 1989; Chatjigeorgiou, 1998) and lump mass method (Nakajima, 1982; Ghadimi, 1987).

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