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Keywords: six degree-of-freedom motion, floating crane, elastic boom, multibody, finite element formulation, wave conditions.

Summary

A floating crane is a crane-mounted ship used for lifting and transporting heavy cargos. Since it operates in ocean waves, the dynamics response analysis of the cargo is required for safe and stable operation. With this purpose, Cha et al. [1] analyzed the six degree-of-freedom (DOF) motions of a cargo suspended from a floating crane based on multibody system dynamics. Meanwhile, it is more reasonable to consider the flexibility of the boom for the analysis, based on the configuration of the cargo and the boom on the floating crane. Therefore, this paper incorporates the elastic boom model in the dynamic response analysis.

In order to be compatible with the six DOF motions of the floating crane and the cargo, an elastic boom is modeled as a set of beam elements with three dimensional deformations caused by tension, bending, and torsion based on the finite element formulation. The deformation vector is expressed using the shape matrix and nodal coordinates. Based on the "floating frame of reference" formulation, the global position vector of the arbitrary point on the elastic beam is expressed in terms of the position vector of the body-fixed reference frame and the deformation vector. The mass matrix of the elastic boom is derived using the global position vector, and the stiffness matrix is derived using the deformation vector.

The multibody system consisting of the floating crane, cargo, and elastic boom is designed. The boom is fixed at the front of the floating crane barge, and the boom tip is connected to the backstay with a single wire rope. The cargo is tied to the boom tip with another wire rope. The wire ropes are extensible.

The augmented formulation [2] for the dynamic equations of motions of the system is derived based on multibody system dynamics. The nonlinear hydrostatic force [3], the linear hydrodynamic force, the wire rope force, and the mooring force are considered as external forces.

Numerical simulation of a 1,300 tons cargo suspended from a floating crane under a regular wave condition of 0.5 m height, 156 m length and 45° heading angle is performed, and the simulation results are compared with the results of Cha et al. [1]. Based on the analysis, an elastic boom is confirmed to cause more dynamic effects on the surge, pitch, and yaw motions of the cargo than a rigid boom. Therefore, it is more reasonable to consider an elastic boom for dynamic response analysis of a floating crane with a heavy cargo under various wave conditions.

References

1: J.H. Cha, M.I. Roh, K.Y. Lee, "Combined Discrete Event and Discrete Time Simulation Framework and Its Application to the Block Erection Process in Shipbuilding", Advances In Engineering Software, 41(4), 656-665, 2010. doi:10.1016/j.advengsoft.2009.12.006
2: A.A. Shabana, "Dynamics of multibody systems", Third edition, Cambridge University Press, 2005.
3: K.Y. Lee, J.H. Cha, K.P. Park, "Dynamic Response of a Floating Crane in Waves by Considering the Nonlinear Effect of Hydrostatic Force", Ship Technology Research, 57(1), 62-71, 2010.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 93 PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: Paper 343 Spatial Motion Analysis of a Floating Crane and a Cargo with Elastic Boom based on a Three-Dimensional Beam K.P. Park¹, J.H. Cha² and K.Y. Lee³ ¹Daewoo Shipbuilding & Marine Engineering, Co., Ltd., Geoje-si, Korea ²Engineering Research Institute, ³Department of the Naval Architecture and Ocean Engineering, Seoul National University, Korea doi:10.4203/ccp.93.343 purchase the full-text of this paper Full Bibliographic Reference for this paper K.P. Park, J.H. Cha, K.Y. Lee, "Spatial Motion Analysis of a Floating Crane and a Cargo with Elastic Boom based on a Three-Dimensional Beam", in , (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 343, 2010. doi:10.4203/ccp.93.343 Keywords: six degree-of-freedom motion, floating crane, elastic boom, multibody, finite element formulation, wave conditions. Summary A floating crane is a crane-mounted ship used for lifting and transporting heavy cargos. Since it operates in ocean waves, the dynamics response analysis of the cargo is required for safe and stable operation. With this purpose, Cha et al. [1] analyzed the six degree-of-freedom (DOF) motions of a cargo suspended from a floating crane based on multibody system dynamics. Meanwhile, it is more reasonable to consider the flexibility of the boom for the analysis, based on the configuration of the cargo and the boom on the floating crane. Therefore, this paper incorporates the elastic boom model in the dynamic response analysis. In order to be compatible with the six DOF motions of the floating crane and the cargo, an elastic boom is modeled as a set of beam elements with three dimensional deformations caused by tension, bending, and torsion based on the finite element formulation. The deformation vector is expressed using the shape matrix and nodal coordinates. Based on the "floating frame of reference" formulation, the global position vector of the arbitrary point on the elastic beam is expressed in terms of the position vector of the body-fixed reference frame and the deformation vector. The mass matrix of the elastic boom is derived using the global position vector, and the stiffness matrix is derived using the deformation vector. The multibody system consisting of the floating crane, cargo, and elastic boom is designed. The boom is fixed at the front of the floating crane barge, and the boom tip is connected to the backstay with a single wire rope. The cargo is tied to the boom tip with another wire rope. The wire ropes are extensible. The augmented formulation [2] for the dynamic equations of motions of the system is derived based on multibody system dynamics. The nonlinear hydrostatic force [3], the linear hydrodynamic force, the wire rope force, and the mooring force are considered as external forces. Numerical simulation of a 1,300 tons cargo suspended from a floating crane under a regular wave condition of 0.5 m height, 156 m length and 45° heading angle is performed, and the simulation results are compared with the results of Cha et al. [1]. Based on the analysis, an elastic boom is confirmed to cause more dynamic effects on the surge, pitch, and yaw motions of the cargo than a rigid boom. Therefore, it is more reasonable to consider an elastic boom for dynamic response analysis of a floating crane with a heavy cargo under various wave conditions. References 1 J.H. Cha, M.I. Roh, K.Y. Lee, "Combined Discrete Event and Discrete Time Simulation Framework and Its Application to the Block Erection Process in Shipbuilding", Advances In Engineering Software, 41(4), 656-665, 2010. doi:10.1016/j.advengsoft.2009.12.006 2 A.A. Shabana, "Dynamics of multibody systems", Third edition, Cambridge University Press, 2005. 3 K.Y. Lee, J.H. Cha, K.P. Park, "Dynamic Response of a Floating Crane in Waves by Considering the Nonlinear Effect of Hydrostatic Force", Ship Technology Research, 57(1), 62-71, 2010. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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