FEM modeling for 3D dynamic analysis of deep-ocean mining pipeline and its experimental verification

Abstract

3D dynamic analysis models of 1000 m deep-ocean mining pipeline, including steel lift pipe, pump, buffer and flexible hose, were established by finite element method (FEM). The coupling effect of steel lift pipe and flexible hose, and main external loads of pipeline were considered in the models, such as gravity, buoyancy, hydrodynamic forces, internal and external fluid pressures, concentrated suspension buoyancy on the flexible hose, torsional moment and axial force induced by pump working. Some relevant FEM models and solution techniques were developed, according to various 3D transient behaviors of integrated deep-ocean mining pipeline, including towing motions of track-keeping operation and launch process of pipeline. Meanwhile, an experimental verification system in towing water tank that had similar characteristics of designed mining pipeline was developed to verify the accuracy of the FEM models and dynamic simulation. The experiment results show that the experimental records and simulation results of stress of pipe are coincided. Based on the further simulations of 1 000 m deep-ocean mining pipeline, the simulation results show that, to form configuration of a saddle shape, the total concentrated suspension buoyancy of flexible hose should be 95%–105% of the gravity of flexible hose in water, the first suspension point occupies 1/3 of the total buoyancy, and the second suspension point occupies 2/3 of the total buoyancy. When towing velocity of mining system is less than 0.5 m/s, the towing track of buffer is coincided with the setting route of ship on the whole and the configuration of flexible hose is also kept well.

Keywords

deep-ocean mining / pipeline modeling / dynamic analysis / finite element method

References

[1] BATH A R. Deep sea mining technology: Recent developments and future projects[C]// Offshore Technology Conference, 21^st Houston. Texas: Paper No. OTC 5998, 1989: 333–340.

[2] ChungJ. S.. Deep-ocean mining issues and ocean mining working group[C]. Proceedings of the 3rd Ocean Mining Symposium, 1999, Goa India, ISOPE: 14-20

[3] LiuS.-j., WangG., LiL.. Virtual reality research of ocean poly-metallic nodule mining based on COMRA’s mining system[C]. Proceedings of the 5th Ocean Mining Symposium, 2003, Tsukuba, Japan, ISOPE: 104-110

[4] ChungJ. S.. Deep-ocean mining technology: Learning curve I[C]. Proceedings of the 5th Ocean Mining Symposium, 2003, Tsukuba, Japan, ISOPE: 1-5

[5] ChungJ. S.. Track-keeping control of seafloor miner by successive learning of unknown velocity and soil properties[C]. Proceedings of the 3rd Ocean Mining Symposium, 1999, Goa, India, ISOPE: 85-92

[6] BRINK A W, CHUNG J S. Automatic position control of a 300 000 tons ship during ocean mining operations[C]// Offshore Technology Conference. Paper No. OTC 4091, 1981: 205–224.

[7] ChungJ. S., WhiteA. K., LodenW. A.. Nonlinear transient motion of deep ocean mining pipe[J]. Journal of Energy Resources Technology, 1981, 103(3): 2-10

[8] FelippaC. A., ChungJ. S.. Nonlinear static analysis of deep ocean mining pipe—Part I: Modeling and formulation[J]. Journal of Energy Resources Technology, 1981, 103(3): 11-15

[9] ChungJ. S., FelippaC. A.. Nonlinear static analysis of deep ocean mining pipe — Part II: Numerical studies[J]. Journal of Energy Resources Technology, 1981, 103(3): 16-25

[10] ChungJ. S., ChengB. R., HuttelmaierH. P.. Three-dimensional coupled responses of a vertical deep-ocean pipe: Part I. Excitation at pipe ends and external torsion[J]. International Journal of Offshore and Polar Engineering, 1994, 4(4): 320-330

[11] ChungJ. S., ChengB. R., HuttelmaierH. P.. Three-dimensional coupled responses of a vertical deep-ocean pipe: Part II. Excitation at pipe top and external torsion[J]. International Journal of Offshore and Polar Engineering, 1994, 4(4): 331-339

[12] MustoeG. G., HettelmaierH. P., ChungJ. S.. Assessment of dynamic coupled bending-axial effects for two-dimensional deep-ocean pipes by the discrete element method[J]. International Journal of Offshore and Polar Engineering, 1992, 2(4): 289-296

[13] HUTTELMAIER H P, CHUNG J S, MUSTOE G G, et al. Eigenvalues of a long vertical pipe by DEM, FEM and exact solution[C]// Proceedings of the 3rd International Offshore and Polar Engineering Conference, 1993: 311–314.

[14] ChengB.-r.. ZH tor method for dynamic analysis in the 3-D beam structure[J]. Discrete element with flexible connecJournal of Tsinghua University, 1996, 36(3): 12-17

[15] JianQ., HeY.-s., WangM.-he.. Numerical study of dynamic behavior of flexible pipes in deep sea mining[J]. Ocean Engineering, 2001, 19(2): 59-64

[16] GuoX.-gang.. Nonlinear dynamic modeling of the fluid-solid-coupled flexible pipe systems for deep sea mining[J]. Engineering Mechanics, 2000, 17(3): 93-104

[17] XiaoL.-jing.The study on kinematic and dynamic characteristics of lift pipe in deep ocean mining[D], 2000, Beijing, Beijing University of Science and Technology: 8-50

[18] RankinC. C., BroganF. A.. An element independent corotational procedure for the treatment of large rotations[J]. Journal of Pressure Vessel Technology, 1986, 108: 165-174