疲劳裂纹扩展速率两种数据处理方法的比较

采用七点递增多项式法和Smith法对20MnHR焊缝与热影响区疲劳裂纹扩展速率试验数据进行处理，求得试样疲劳裂纹扩展速率及裂纹尖端应力强度因子范围的值，并对试验结果进行比较分析。试验分析说明较薄试样可以得到疲劳裂纹扩展速率的斜率转折点，以平面应变性质为基础的Paris裂纹扩展速率定律能够安全地应用。在较大范围的扩展区域内，用七点递增多项式法得到的疲劳裂纹扩展速率比Smith法具有较高的安全系数，可应用于实际的焊接结构，并具有一定的安全性。

COMPARISON WITH TWO DATA PROCESSING METHODS ON FATIGUE CRACK GROWTH RATE

The tested data of fatigue crack propagation rate on weld and heat affected zone of 20MnHR was dealt with seven point incremental polynomial method and Smith method to compute crack growth rate and range of stress intensity factor, tested results was comparatively analyzed. The analyses show that the inflective point of crack growth rate can be obtained if the specimen is sufficiently thin and the Paris crack propagation law based on plane strain behavior can be used safely. Moreover, in the greater crack propagation zone, there is higher safety factor to employ the fatigue crack propagation formulas obtained with seven point incremental polynomial method than with Smith method, thus it could be applied for practical welded structures with considerable confidence.