Abstract Mode I fracture mechanics has been relatively mature but mixed mode fracture mechanics continues to present challenges, in particular for ductile materials under multiaxial stresses. Since most engineering materials, e.g., metals, exhibit elasto-plastic or ductile behaviour and are subjected to inclined cracks and/or multiaxial loading, there is a well justified need to establish a solid understanding of their fracture behaviour under mixed modes. The intention of this paper is to critically review mixed mode fracture criteria for predicting the crack propagation in metals. Experimental methods for determining the fracture toughness under different mode mixities are reviewed and discussed. More importantly, research gaps in current studies are identified and further research needs are proposed. Through this review, it is found that the mixed mode fracture criteria need to be based on elasto-plastic fracture mechanics to account for large plastic deformation, and that for ductile metals, the addition of Mode II or Mode III loading can lead to a remarkable decrease of total fracture toughness of the metal, whilst the total fracture toughness of less ductile metals is insensitive to the addition of Mode II or Mode III loading. This review can contribute to the development of advanced mixed mode fracture criteria and testing methods for ductile metals.

中文翻译：

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金属混模断裂综述

摘要 模式 I 断裂力学已经相对成熟，但混合模式断裂力学继续提出挑战，特别是对于多轴应力下的延性材料。由于大多数工程材料（例如金属）表现出弹塑性或延展性，并且会受到倾斜裂纹和/或多轴载荷的影响，因此有充分理由充分了解它们在混合模式下的断裂行为。本文的目的是批判性地审查用于预测金属裂纹扩展的混合模式断裂标准。回顾和讨论了在不同模式混合下确定断裂韧性的实验方法。更重要的是，确定了当前研究中的研究空白，并提出了进一步的研究需求。通过这次审查，发现混合模式断裂准则需要基于弹塑性断裂力学来解释大的塑性变形，而对于延性金属，添加模式II或模式III加载可以导致总断裂显着减少金属的韧性，而韧性较差的金属的总断裂韧性对模式 II 或模式 III 载荷的增加不敏感。本综述有助于开发用于延展性金属的先进混合模式断裂标准和测试方法。而韧性较差的金属的总断裂韧性对模式 II 或模式 III 载荷的增加不敏感。本综述有助于开发用于延展性金属的先进混合模式断裂标准和测试方法。而韧性较差的金属的总断裂韧性对模式 II 或模式 III 载荷的增加不敏感。本综述有助于开发用于延展性金属的先进混合模式断裂标准和测试方法。