Abstract Ice bending is a major failure mechanism of level ice when ships and marine structures interact with level ice. This paper aims to investigate the ice bending and ice load when level ice collides on ships and marine structures using numerical simulation method, and compare the numerical results with field test. The fracture of ice is simulated with extended finite element method (XFEM), and cohesive zone concept is used to describe the crack propagation. In order to consider the characteristics of S2 columnar ice, a transversely isotropic elastic material model is used for the ice bulk elements, and a transversely isotropic Tsai-Wu failure criterion is adopted to predict the initiation of cracks. A well-controlled field test of a landing craft bow colliding with level ice in Baltic Sea is simulated to verify the numerical scheme. The ice plate's continuous deformation, crack initiation and crack propagation at different impact velocities and angles are simulated and the results are discussed. In the simulation, the bending crack emerges at the midline of the top surface of ice plate, then propagates towards free boundary, and finally a circumferential crack forms. It is found that with the impact velocity increases, the bending load increases and the fracture size (perpendicular distance from the crack to the contact edge) decreases. And as the angle between the landing craft bow and vertical direction increases, the bending load and the fracture size decrease. The simulated results corresponds well with the field test. The competition between the circumferential crack and radial crack is also found in the simulation and will be discussed in this paper. The results show that this method well simulates the bending of level ice and predict the ice load, and provides a good approach for investigating the mechanism of different forms of level ice fracture.

中文翻译：

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基于XFEM的考虑波罗的海冰横向各向同性的水平冰对登陆艇船首的影响数值模拟

摘要 冰面弯曲是船舶和海洋结构与冰面相互作用时冰面发生的主要破坏机制。本文旨在利用数值模拟方法研究平冰碰撞船舶和海洋结构物时的冰弯曲和冰载荷，并将数值结果与现场试验进行比较。采用扩展有限元法（XFEM）模拟冰的断裂，并使用内聚区概念来描述裂纹扩展。为考虑S2柱状冰的特性，冰块单元采用横向各向同性弹性材料模型，采用横向各向同性Tsai-Wu破坏准则预测裂纹萌生。模拟了在波罗的海与平冰碰撞的登陆艇船首的良好控制的现场测试，以验证数值方案。模拟了冰板在不同冲击速度和角度下的连续变形、裂纹萌生和裂纹扩展，并对结果进行了讨论。在模拟中，弯曲裂纹出现在冰板顶面中线处，然后向自由边界扩展，最终形成环向裂纹。发现随着冲击速度的增加，弯曲载荷增加并且断裂尺寸（从裂纹到接触边缘的垂直距离）减小。并且随着登陆艇船首与垂向夹角的增大，弯曲载荷和断裂尺寸减小。模拟结果与现场试验吻合良好。模拟中还发现了圆周裂纹和径向裂纹之间的竞争，将在本文中进行讨论。