基于柔度法的开口角隅试样裂纹扩展数值计算

Numerical calculation on crack propagation of opening corner specimen based on flexibility method

开口结构的角隅区域由于几何不连续易产生应力集中,复杂工况下的循环交变应力使角隅区域的损伤逐渐累积而产生疲劳裂纹,影响结构的整体安全和正常运行。针对开口角隅区域裂纹扩展问题,依次建立自主设计的开口角隅试样二维和三维模型,并分别采用常规有限元法和扩展有限元法(XFEM)进行数值模拟。最终得到3种不同计算方法的裂纹尖端应力强度因子K,并基于柔度法换算得到裂纹长度与应力强度因子间的显式关系式。结果表明:圆角半径对裂纹扩展影响不大,研究成果可为开口结构角隅区域的裂纹扩展特性研究提供理论依据和试验基础。

The corner area of the opening structure is prone to stress concentration due to its geometric discontinuity. The cyclic alternating stress under complex working conditions makes the damage to the corner area gradually accumulate to produce fatigue cracks,which significantly affects the overall safety and normal operation of the structure. In order to solve the problem of crack propagation in the opening corner area,the two dimensional and three dimensional models of the self-designed opening corner specimens were established in this paper. Also the conventional finite element methods and extended finite element methods(XFEM)were used for numerical simulation. Finally,the stress intensity factors K at the crack tip under three different calculation methods were obtained,and an well-fitting explicit relationship between the crack length and the stress intensity factor was obtained by conversion based on the flexibility method. The results show that the corner radius has little effect on crack propagation. This paper can provide theoretical and experimental basis for the research of crack propagation on the corner region of the opening structure.