Dynamic modeling and analysis of maritime alongside replenishment system using multibody dynamics method

Abstract

Alongside replenishment at sea is essential for the sustainable operation of ocean-going ships. Current researches mainly focus on hydrodnamics, control methods and simple static analysis, however, the dynamic modeling and analysis of the system are hardly investigated. In this paper, an new dynamic model of the alongside replenishment system is presented using the multibody dynamics method. The corotational cable element and the contact law are employed to formulate the cable-pulley interactions. To improve the computational efficiency, a simplified dynamic model is proposed, in which the effect of the cable is modeled as a force element using the constant tension characteristic while the cable's mass is taken into account. The validity of the simplified method is verified by the detailed model. The mechanical behaviors of the replenishment system are studied. We find that the dynamic analysis is necessary in rough sea conditions while the static equilibrium analysis doesn't work well. The influence of several model parameters is investigated. It shows that the cargo safety can be improved by increasing the height difference and tension force while decreasing the transmission distance. Moreover, the resonance of the cargo can be excited if the ship motion frequency is near the natural frequency of the system.