基于XFEM的核电安全端应力腐蚀裂纹扩展研究

发布时间：2018-04-22 23:24

本文选题：应力腐蚀开裂 + 弹塑性　；参考：《西安科技大学》2017年硕士论文

【摘要】：异种金属焊接残余应力是引发安全端应力腐蚀开裂(SCC)的主要因素之一。本文借助扩展有限元方法(XFEM),模拟了核电安全端焊接接头受残余应力影响下的裂纹扩展过程,井借助子模型技术研究了裂纹扩展过程中特定位置裂尖区域内的应力应变场,完成的主要研究工作有:(1)利用预定义温度场建立了异种金属焊接接头残余应力加载方式,同时利用最大主应力准则,建立了核电一回路安全端弹塑性材料裂纹动态扩展模拟方法。(2)研究了焊缝金属中的裂纹扩展长度对应力应变场的影响规律,以及裂纹扩展和残余应力场的相互作用规律;并通过子模型技术研究了扩展裂纹尖端详细的裂尖应力应变场分布,以此来判定裂纹的扩展、止裂,以及预测裂纹扩展方向。(3)研究了焊缝金属和材料界面初始裂纹长度对裂纹扩展的影响规律,得出了初始裂纹长度对裂纹扩展驱动力、裂纹扩展速率、裂尖应力应变场的影响规律;讨论了两侧材料特性对界面裂纹扩展的影响规律。(4)讨论了安全端焊缝金属靠近压力容器侧(焊缝金属亚界面)以及压力容器金属靠近焊缝侧(压力容器亚界面),裂纹位置对裂纹扩展特性的影响规律,得到了近界面处材料力学性能不均匀性对裂纹扩展过程中的应力应变场分布、开裂速率、扩展路径偏移的影响规律。本论文研究结果对核电安全端焊接接头应力腐蚀开裂裂纹扩展特性研究提供了一定的理论基础和依据。
[Abstract]:The residual stress of dissimilar metal welding is one of the main factors causing SCC (stress corrosion cracking) at the safe end. In this paper, by means of the extended finite element method (EFEM), the crack propagation process of welded joints at the safety end of nuclear power plants under the influence of residual stress is simulated. The stress and strain field in the crack tip region at a specific location during crack propagation is studied by means of submodel technique. The main research work accomplished is: (1) using predefined temperature field, the residual stress loading mode of dissimilar metal welded joint is established, and the maximum principal stress criterion is used at the same time. The simulation method of crack dynamic propagation in primary circuit safety end elastoplastic material of nuclear power is established. The influence of crack propagation length on stress and strain field and the interaction between crack propagation and residual stress field in weld metal are studied. The stress and strain distribution at the tip of the propagating crack is studied by means of the submodel technique to determine the crack propagation and stop the crack. The influence of initial crack length on crack growth at the interface of weld metal and material is studied, and the driving force and rate of crack propagation are obtained. The effect of stress and strain field on crack tip; The influence of material characteristics on the crack growth of interface is discussed. The safe end weld metal near the pressure vessel side (weld metal subinterface) and the pressure vessel metal near the weld side (pressure vessel sub-interface) are discussed. The influence of crack location on crack growth, The influence of nonuniformity of material mechanical properties on the distribution of stress and strain field, crack rate and propagation path deviation during crack propagation is obtained. The results of this paper provide a theoretical basis for the study of stress corrosion cracking crack propagation characteristics of safety end welded joints in nuclear power plant.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM623

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