含缺陷油套管的抗弯曲特性研究

本研究选用J55油套管，用人工缺陷法在外径为73mm的油套管外表面预制了缺陷，通过三点弯曲对称加载试验，研究了缺陷管的抗弯强度，对改进的NSC准则进行实验检验。结果表明，在缺陷角较小时，改进的NSC准则能给出与试验数据接近的预测结果，但对于在缺陷角较大的情形，预测结果却不理想。根据试验结果，本文进一步提出了一个含有缺陷几何参量的新公式。新公式能很好地预测含缺陷管的抗弯曲能力。

Bending resistant behavior of local defected oil well pipes

J55 oil well pipe is employed to study the defect influence on its bending resistance. Artificial defect is machined on 73mm oil well pipes, and instron 1346 is employed to perform the bending testing, the effectiveness of the modified NSC criterion (net section collapse criterion) is checked. The results show that the modified NSC criterion gives good prediction only in condition of small defect angle. By analyzing the test data, a new formula is proposed, which could be employed to estimate the ultimate bending moment with geometric coefficients of the defect. The results show that the predictions of the new formula agree with the test data appropriately.