Research On Traction And Transverse Positioning Force For Large Ship Docking

Large ship docking and undocking is operated by traction systems which are installed on both sides of dock. Traction forcesare affected by system rigidity, ship inertia and multiple environment factors. And also the combination of these factors can result in complicated coupling so that it is difficult to accurately calculate the necessary traction force. Although the traction force formula is provided in related design specification of dock, some factors do not be considered in this formula and the ranges of key parameters are large. Thus, the accurate traction force cannot be obtained so that it cannot effectively aid designer.For traditional traction system, traction cart which is driven by winch is installed on each side of dock to pull the ship from dock. During the ship docking and undocking, the operation should be cancelled due to large drift, thus the ship's position can be corrected by a winch provided at both sides of the dock. Under the influence of unfavorable environment, many corrections need to be done which spend much time and labor. In recent years, in order to reduce labor intensity and improve work efficiency, the transverse positioning cart is used in the new dock. Shipping route can be maintained during the ship docking and undocking without human interference by transverse positioning cart which can move along track powered by winch. However, transverse positioning cart can affect the track force and transverse force. And also, the directional ship track designed by traditional design method maybe result in severe accident because the transverse force directly acts on the directional ship track. So it is crucial to study traction and transverse force during docking and undocking.This paper analyzed influence factors on traction force, and also theoretically analyzed factors such as wind, wave, flow and startup time. Based on test method of physical model, factors such as wind, wave, and flow and startup time were simulated in the laboratory, and also designed special traction device and measurement system. Multiple working conditions were simulated such as force(transverse and oblique), influence factors(each and several), ship status(stationary and dynamic) and startup time(40s and 120s). Cable force was measured under different working condition at different location during the docking and undocking. The experiment data was compared with traditional traction force formula to correct this formula, and also obtained the data range of transverse positioning force. This study provides the basis for traction force calculation and the reference for the time of ship docking and undocking. This paper discussed the configuration model of shipping track and transverse positioning cart. The traction force was analyzed based on experiment data. Finally, the traction system was optimally designed by finite element analysis method.