|So far, in the motion analysis, wire ropes have been modeled by incompressible springs which only exert a force when it is extended. Thus, we cannot consider their properties like real wire ropes, such as twisting and bending. Moreover, we have often seen that they generated an unstable motion, and sometimes stiffness problems, especially when the spring coefficient is very large and the mass is not large enough. Therefore, to reflect not only stretching, but also twisting and bending, we adapt the constraint-based wire rope model which discretizes the wire rope as small elements having length and angular constraints. In addition, we use discrete vairational method which is proven to be numerically stable for the case of linear holonomic constraints. As a result, the equation of motion of a floating crane and a heavy load connected by constraint-based wire rope is formulated. Linearized hydrodynamic and hydrostatic forces are considered as the external forces which induce the floating crane motion. It is confirmed that the motions of a floating crane and a heavy load using constraint-based wire rope are stable compared with the motions using incompressible spring.
Hye-Won Lee, Seung-Ho Ham, Jeong-Woo Hong, Sol Ha, Myung-Il Roh, "Motion Analysis of a Heavy Load Suspended by a Floating Crane Using Constraint-based Wire Rope based on Discrete Variational Method", Proceedings of the 28th Asian-Pacific TEAM(Technical Exchange and Advisory Meeting on Marine Structures) 2014, Istanbul, Turkey, pp. 450-456, 2014.10.13-16