Application of a topological modelling approach of multi-body system dynamics to simulation of multi-floating cranes in shipyards

Abstract

A heavy cargo such as a ship block weighing over 5000 tons is erected by multi-floating cranes in a shipyard. In this study, the coupled equations of motion of the floating cranes and the cargo are set up automatically by topological modelling approach of multi-body system dynamics for analysing the dynamic response of a cargo. The non-linear hydrostatic force with wave elevation, the linear hydrodynamic force, wire rope force, and gravitational force are regarded as external forces. The tension of wire ropes connecting the floating cranes and the cargo is calculated for waves with various directions and amplitudes. To evaluate the applicability of the proposed method, it is applied to a dynamic simulation problem of heavy cargo suspended from two floating cranes and a sub-barge between two cranes. In the results of the simulation, waves with 90° direction is more important to the tension of the wire ropes than the waves with 0° and 45° directions, and the ratio of the tension to the wave amplitude is calculated.