蠕变-疲劳载荷下高温构件不连续部位的损伤机理及设计准则研究

Focusing on the requirements of the strength safety and security for the new generation key equipment, including the ultra-supercritical (USC) power plants, the aim of this project is to address the damage mechanism and design criterion for local discontinuity of high temperature components under creep-fatigue loadings. The following issues will be included in the present project: (1) Describing the microscopic damage mechanism of notched components at elevated temperatures by conducting creep-fatigue test of C/U/V-shape notched components and analyzing the effect of loading parameters (e.g. holding time and stress ratios) and geometrical parameters on microstructural evolutions. (2) Establishing a creep-fatigue damage variable with the notch effect considered based on the relationship between evolutions of microstructure and stress/strain behavior, and then building a creep-fatigue damage model coupling with creep and cyclic constitutive equations based on continuum damage mechanics. (3) Establishing the relationship between the strain criterion and fatigue loadings/multi-axial stress/design life through experimental studies and finite element analyses coupling with the proposed damage model. This project is expected to provide new theoretical basis for the stress analysis and evaluation on local discontinuity of high temperature components under creep-fatigue loadings and to give scientific support to the creep-fatigue design for components at elevated temperatures.

面向超超临界（USC）电站等新一代高端装备的强度安全和保障需求，针对蠕变-疲劳载荷下高温构件不连续部位的损伤机理及设计准则开展研究。主要包括：（1）开展缺口构件（C/U/V型）在不同保载时间、应力比下的蠕变-疲劳试验，研究不同载荷参数、缺口几何参数对缺口效应及微细观组织演化行为的影响，阐明高温缺口构件的微观损伤机理；（2）缺口构件应力应变演化行为与蠕变-疲劳微观损伤规律相结合，纳入缺口效应对微细观组织演化的影响，建立高温构件的微观损伤描述方法，并耦合蠕变/循环本构方程，形成基于物理的高温构件蠕变-疲劳损伤力学模型；（3）基于建立的蠕变-疲劳损伤力学模型，开展损伤有限元分析，并结合蠕变-疲劳实验研究，建立与疲劳循环周次、多轴应力、设计寿命相关联的应变设计准则。本项目有望为高温构件不连续部位的局部应力处理提供新的理论依据，为高温构件的蠕变-疲劳强度设计提供科学支持。

针对高温构件不连续部位的蠕变-疲劳强度设计问题，采用理论分析、实验观察与数值分析相结合的研究方法，在高温装备材料/结构件的蠕变-疲劳微观损伤机理、高温部件的蠕变-疲劳损伤力学模型、高温构件不连续部位的强度设计准则等方面取得重要进展，形成了高温构件不连续部位的蠕变-疲劳强度设计方法和准则。本项目有望为高温构件不连续部位的局部应力处理提供新的理论依据，为高温构件的蠕变-疲劳强度设计提供科学支持。发表论文19篇（其中，国际SCI论文7篇，国内核心期刊论文6篇），授权软件著作权4件。部分成果获得中国机械工业科技进步二等奖（2019）、中国压力容器学会青年论文竞赛奖（2017）、全国反应堆结构力学会议优秀论文奖（2018）。项目负责人入选华东理工大学青年英才培育计划（2019）。培养博士研究生2人，硕士研究生2人。