A global crack - line displacement fitting procedure ( gcdfp ) for computing stress intensity factors ( sif ) has been developed . the precision of sif is compatible with the corresponding cod data 使用paris公式求出裂纹前缘各点的裂纹扩展增量,并用三次b -样条函数对这些增量进行拟合,得到新的光滑裂纹前缘。