Capsizing mechanism of laterite-nickel ore transport ship under wave excitation

The laterite-nickel ore, kaolin and red sand soil with the characteristics of fluidization typical cargoes were selected to conduct the critical water content test and fluidization test, and the critical water content rate was obtained. Using the excitation rolling device, the excitation rolling motion experiments with different excitation amplitudes and frequencies were carried out. The time history characteristics of overturning force and moment of three different cargoes under different water content rates were compared. Capsizing mechanism test was designed, the laterite-nickel ore with critical water content rate was chose as a sample, and the waves were generated in wave tank to excite rolling motion so as to recreate the capsizing process of the laterite-nickel ore transport ship. The high-speed camera was used to catch the variation of free liquid surface. The free liquid surface was segmented by using the digital processing technology. The changes of floating center and barycenter of laterite-nickel ore transport ship during the capsizing process were also discussed based on the free liquid surface's condition. Analysis result shows that the critical water content rates of the laterite-nickel ore, red sand soil and kaolin are 33.6%, 22.0% and 39.4%, respectively. The sloshing force and moment of soils with different natures show different properties even though their excitation conditions are the same. When the phase differences are 90° and 270°, the asymmetric moment increases 4.37 times as much as that when the phase differences are 0° and 180°. The main reason for the capsizing of laterite-nickel ore transport ship is that the liquid cargo's sloshing results in that the rolling moment increases and the dynamic stability decreases. At the same time, the sloshing moment is related to the nature of goods, period of excitation, viscosity, amplitude of incentive and many other factors.