冰区航行中船体结构冰压力分布特性的离散元分析

DEM analysis for the distribution of ice pressure on ship hull during navigating in ice regions

冰区船舶表面冰压力分布规律是其结构安全预警和冰载荷监测的重要辅助信息。本文采用基于GPU(Graphics Processing Unit)并行和粘结-破碎模型的离散元方法模拟平整冰在不同冰况条件下的破碎过程,进而获得船体结构表面的冰压力分布和大小。在冰压力的计算中,考虑时间上的累积效应,即累积最大值和累积平均值,从多个角度分析了船体结构表面的冰压力危险区域和冰压力分布特性。通过船体结构直行破冰的离散元模拟,分析了船体结构的总体冰载荷和局部冰压力。为验证本文方法在船体结构冰压力分析中的可靠性,根据冰载荷的IACS规范计算了船体结构与大块浮冰自由碰撞过程,对比分析了碰撞点上的冰压力。计算结果表明,离散元计算结果与规范对比误差保持在6.7%~18.1%之间。本文方法为冰区船舶的设计研发提供了可靠的分析手段,其计算结果可为船体结构的冰区航行安全预警和冰载荷监测提供合理的辅助决策信息。

Distribution characteristics of ice pressure on ship hull are important auxiliary information for structural safety early-warning and ice load monitoring of ice-going ships.In this paper,the Discrete Element Method(DEM)based on GPU(Graphics Processing Unit)parallel and bond-break model is developed to simulate the breaking process of level ice under different ice conditions,and the distribution of ice pressure on the ship hull can be obtained.In the calculation of ice pressure,considering the cumulative effect on time,i.e.the cumulative maximum and cumulative average values,the dangerous area of ice pressure on the ship hull and the distribution characteristics of ice pressure are analyzed from different viewpoints.The global ice loads and local ice pressure on ship hull during ship navigation are analyzed in DEM simulations.In order to verify the reliability of this method in the analysis of ice pressure on ship hull structure,the free collision process between ship hull structure and large ice floe is simulated while the ice pressures at the collision positions are analyzed and compared with the ice load code of IACS(International Association of Classification Societies).The results show that the error between the DEM results and the IACS code is from 6.7%to 18.1%.The DEM for sea ice simulation proposed in this paper provides a reliable analysis approach for the design and development for ice-going ships.The simulation result can provide reasonable assisted decision for navigation safety early-warning and ice load monitoring of ship hull in ice regions.