基于扩展有限元的Q345R材料平板裂纹扩展模拟研究

Q345R钢具有良好的综合力学性能和工艺性能，是制造压力容器最常用的材料之一。裂纹是造成压力容器失效和破坏的首要原因，在压力容器的检测和维护过程中，对裂纹的产生和发展进行模拟和分析具有重要的意义。本研究针对Q345R钢使用过程中常出现的中心裂纹和单边裂纹两种典型的裂纹形式，运用扩展有限元方法，分别模拟在拉伸状态下的中心裂纹、在低周疲劳作用下的单边裂纹扩展过程；并分析裂纹扩展过程中不断变化的裂纹尖端处的应力、应变，研究裂纹在Q345R材料中的扩展规律。结果表明:在裂纹扩展变化的过程中，应力集中现象首先会在裂纹尖端处出现，裂纹面处的应力最小，裂纹面两端应力对称分布，整个应力分布趋势符合断裂力学理论，证明通过运用扩展有限元方法来对Q345R材料中的裂纹扩展过程模拟分析的可靠性。

Simulation Study on Crack Propagation of Q345R Material Based on Extended Finite Element Method

Q345R steel has good comprehensive mechanical properties and process properties and is one of the most commonly used materials for manufacturing pressure vessels. Cracks are the leading cause of failure and damage to pressure vessels. Therefore, it is of great significance to simulate and analyze the generation and development of cracks during the detection and maintenance of pressure vessels. In this paper, two typical crack forms, center crack and one-sided crack often appear in the process of Q345R steel. The extended finite element method is used to simulate the crack propagation process of a two-dimensional flat plate center crack under tensile state and one-sided crack under low cycle fatigue. The stress changes and strain changes at the crack tip during the crack propagation process are analyzed, and the crack propagation law is also studied. The results show that stress concentration occurs at the crack tip during crack propagation, The stress at the crack surface is the smallest, the stress at both ends of the crack surface is symmetrically distributed, and the whole stress distribution trend is consistent with the theory of fracture mechanics. It is proved that the extended finite element method is used to simulate the reliability of crack propagation.