ABSTRACT

Accidental events such as collision, grounding, and explosion in marine structures can cause plastic deformation and structural damage. Various fracture models based on different mechanical concepts have been proposed to predict damage extents involving ductile fracture. In this paper, some fracture models were evaluated: Maximum shear stress, Cockcroft-Latham, Johnson-Cook, Modified Mohr-Coulomb, Lou-Huh, and Hosford-Coulomb models. The model parameters were identified for two shipbuilding steel grades: AH36 and DH36. A hybrid experimental-numerical approach was adopted. The parameters of six fracture models were identified using an optimisation algorithm based on the extracted loading paths from the numerical simulations and adopting a linear damage accumulation law. The calibrated fracture models are presented in stress triaxiality and Lode angle parameter space as a 3D fracture locus, and under plain stress condition as a function of the stress triaxiality as a 2D fracture locus. The predictive capabilities and flexibility of the evaluated fracture models were discussed.

摘要

海洋结构中的碰撞，接地和爆炸等意外事件可能会导致塑性变形和结构损坏。已经提出了基于不同力学概念的各种断裂模型来预测涉及韧性断裂的破坏程度。在本文中，我们评估了一些断裂模型：最大剪切应力，Cockcroft-Latham，Johnson-Cook，改良的Mohr-Coulomb，Lou-Huh和Hosford-Coulomb模型。确定了两个造船钢种的模型参数：AH36和DH36。采用了混合实验-数字方法。使用优化算法，基于数值模拟中提取的载荷路径，并采用线性损伤累积定律，使用六个优化算法确定了六个断裂模型的参数。校准后的断裂模型在应力三轴性和Lode角参数空间中表示为3D断裂轨迹，在普通应力条件下作为应力三轴性的函数表示为2D断裂轨迹。讨论了评估断裂模型的预测能力和灵活性。