Development of constraint-based fracture mechanics methodologies for structural integrity assessments and fatigue life predictions

高性能工程结构的安全运行，如核压力容器、天然气管道、海洋和航空航天工业等，具有重要的现实意义。为了确保结构的完整性，必须进行考虑缺陷行为的断裂力学分析，以评估这些部件在使用寿命内的安全裕度。传统的断裂力学是基于单个参数(例如J、K或CTOD)唯一地表征裂纹尖端的应力和应变场的假设。然而，人们现在已经很好地理解，单个参数通常不能完全表征裂纹尖端的应力应变场。这就产生了所谓的约束效应。在过去的18年里，在描述约束效应方面取得了重大的研究进展。使用额外的断裂参数来量化平面内约束效应的方法已经被很好地建立起来。

Safe operations of high performance engineering structures, such as those in nuclear pressure vessels, gas pipelines, offshore and aerospace industries, are of practical significance. To assure the structural integrity, it is essential that fracture mechanics analyses considering the behavior of defects are conducted to assess the safety margins over the service life spans of these components. Conventional fracture mechanics are based on the assumption that a single parameter (e.g. J, K or CTOD) uniquely characterizes the crack tip stress and strain fields. However, it is now well understood that a single parameter generally cannot completely characterize the crack tip stress strain fields. This gives rise to the so-called constraint effect. Significant research progress has been made over the past 18 years in characterization of constraint effects. Methods of quantifying the in-plane constraint effects using an additional fracture parameter have been well-established.