循环载荷下考虑累积塑性影响的船体板CTOD理论及数值模拟研究

裂纹尖端张开位移(CTOD)是研究大范围屈服的低周疲劳破坏的重要参数之一，其值可反映结构材料抵抗低周疲劳裂纹形成和扩展的能力，是评估结构材料韧性的重要参量以及分析低周疲劳破坏引起裂纹扩展的主要控制参量。文章基于弹塑性断裂力学理论，从循环J积分着手，以裂纹尖端累积塑性应变为重要参量，建立循环载荷下船体板CTOD理论模型，并在有限元模拟中分析了应力比、应力幅等相关因素影响。将本模型结果与有限元计算结果进行了比较，发现结果吻合良好。结果表明：在考虑累积塑性影响下，该模型能较好地反映在循环载荷下船体板CTOD的变化规律，同时也为正确评估循环载荷下船体板低周疲劳破坏与累积塑性破坏两种破坏模式耦合作用的总体断裂破坏提供了途径。

Theoretical and Numerical Research on CTOD for Ship Plate under Cyclic Loading Considering Accumulative Plastic Strain

The Crack Tip Opening Displacement (CTOD) is one of the important parameters for study-ing the low-cycle fatigue of plate sustaining large scale yielding. The CTOD value can reflect the a-bility of material resistance to crack initiation and propagation, and it is an important parameter to evaluate material toughness as well as the main controlling parameter to analyze the crack propaga-tion due to low-cycle fatigue damage. In this paper, based on the theory of elastic-plastic fracture mechanics, the cyclic J integration is explored as breakthrough point and accumulative plastic strain at crack tip as the significant parameter, an analytical model is presented to determine the CTOD for the central-through cracked plates subjected to cyclic axial in-plane loading. Also, the finite element analysis is conducted to investigate the influence of stress ratio and stress amplitude. The new ac-cumulative plastic strain-based CTOD estimation formulations presented in this paper provides a new way for low-cycle fatigue analysis considering accumulative plastic damage for central-through cracked plates under high cyclic loadings.