屈服后表面裂纹与穿透裂纹的等效裂纹长度换算

The Equivalent Conversion between Yielded Surface Crack and Through Crack

在较小范围屈服条件下,将D-M模型和弹塑性线弹簧模型相结合,建立了屈服后一般扁壳表面裂纹的计算模型,导出了其控制方程和相应的COD计算公式。在此基础上,提出了屈服后一般扁壳表面裂纹与平板穿透裂纹的等COD换算方法。通过各种影响因素的分析并去除次要因素,最终给出了该等效换算关系的简单拟合公式。计算结果表明,该分析方法简便且有足够的工程精度,适应于在役压力容器等结构的现场快速断裂评定。

Under the hypothesis of small scale yielding, the calculating model of a surface crack in a general oblate shell is established by combining the D-M model and elastoplastic line spring model, and the governing equation and the mathematical formula of COD are derived. Based on this, the equivalent COD conversion relation between a yielded surface crack in an general oblate shell and a through crack in an infinite plate is derived. By analyzing all kinds of influencing factors and abandoning the subordinate factors, a simple fitting formula of the equivalent COD coversion is presented lastly. The numeric results prove that the method in the paper is simple and has enough engineering analyzing precision, and is the same with the quick fracture assessing of structure such as pressure vessel in service.