Theory of Critical Distances (TCD) collects several methods adopted in failure prediction of components provided with stress concentration features. The idea of evaluating stress effect in a zone rather than in a single point was proposed decades ago but, only thanks to relatively recent works, TCD concepts showed to be a successful extension of Linear Elastic Fracture Mechanics (LEFM), able to assess strength and fatigue life. The increasing computational power has made Finite Element Method (FEM) widespread, hence stress fields can be easily extracted and used as input data for fatigue post-processing and durability analyses. In this scenario, TCD reveals as a powerful tool which, thanks to the introduction of a single material parameter (critical distance, $L$), integrates classical fracture models by considering the presence of microscale phenomena acting in fracture process. In this sense, TCD behaves as a link between continuum mechanics and LEFM. Modalities and reasons for this connection to occur are interesting points of further investigations. Literature on TCD and its theoretical-experimental background is quite extended, nevertheless few industrial applications are available in literature to the best of authors’ knowledge. In this paper, an overview of concepts and applications related to TCD are reported highlighting the relevance of theoretical arguments in actual applications.

临界距离理论（TCD）收集了在具有应力集中特征的组件的故障预测中采用的几种方法。评价区域而不是单点应力效应的想法是几十年前提出的，但是，仅由于相对较新的工作，TCD概念才证明是线性弹性断裂力学（LEFM）的成功延伸，能够评估强度和强度。疲劳寿命。不断增长的计算能力使有限元方法（FEM）广泛普及，因此可以轻松提取应力场并将其用作疲劳后处理和耐久性分析的输入数据。在这种情况下，由于引入了单个材料参数（临界距离，$\mathrm{大号}$），通过考虑在断裂过程中起作用的微观现象的存在来整合经典断裂模型。从这个意义上讲，TCD充当连续体力学与LEFM之间的联系。这种连接发生的方式和原因是进一步研究的有趣点。关于TCD及其理论实验背景的文献已经相当广泛，但据作者所知，在工业上很少有工业应用。在本文中，对与TCD相关的概念和应用进行了概述，突出了理论论证在实际应用中的相关性。