| The fluidization of ore transported by ship has always been one of the hot issues concerned by the transportation engineering specialty.When large bulk carrier transports the cargoes that are easy to fluidize,due to the movement of the ship,the water will be separated out from the cargoes,and the water content of the ore may exceed the TML proposed by the IMSBC,forming a mixture with mud on the surface.In the process of ship navigation,the cargo will continue to suffer the effect of external load,and the mixture will continue to move.If the mixture follows the cargo tank movement and is difficult to restore to its original state,it will lead to the reduction of the ship’s restoring moment,increase the ship’s inclination,and reduce the ship’s stability.If the sea condition is not good,the ship will even capsize,and the time from cargo fluidization to capsizing is very short,so it is difficult to rescue.In the IMSBC,the ore cargo in the easy fluidization cargo belongs to the soil,which needs to be applied to the soil mechanics knowledge.In this paper,the related properties of soil mechanics are analyzed and the parameters of iron concentrate are studied.Through the analysis of the discrete element method to determine the use of the discrete element edem software for simulation,a three-dimensional cargo tank model is established,the simulation calibration test of the angle of repose is carried out,the correctness of the model is verified,and the simulation of the movement of iron concentrate without water content in the tank is carried out.Then the correctness of changing the friction coefficient to replace the different moisture content is verified.The movement simulation of the aqueous iron concentrate in the cabin is carried out.The changes of normal contact force,particle kinetic energy and center of gravity deviation are analyzed.The simulation results of the non aqueous iron concentrate and the aqueous iron concentrate are compared,and the following conclusions are drawn:(1)Through the numerical simulation of the angle of repose experiment,the correctness of the model is verified,and it is proved that the edem software can be used to simulate the movement of easy flow cargo in the cargo hold.(2)It is verified by the model that the method of changing the friction coefficient of particles instead of different moisture content of particles can be applied to the simulation of the movement in the cargo tank with the consideration of moisture content,which is more accurate than the method without consideration of water.(3)By analyzing the changes of normal contact force,kinetic energy and center of.gravity deviation of particles under various working conditions,it is concluded that: when other variables are fixed,the movement range of particles decreases obviously with the increase of friction coefficient of particles;the increase of rolling range and rolling frequency will lead to the increase of center of gravity deviation of particles and the more violent collision;collision The change of recovery coefficient has little effect on the movement of particles;when the loading volume is fixed,the smaller the particle size distribution,the larger the movement range of particles;with the increase of particle loading,the normal contact force and kinetic energy of particles will maintain a higher water level. |
