带环向表面裂纹矿用钻杆静扭试验及应力场分析

Static torsion test and stress field analysis of the coal mine drilling rod with surface circumferential crack

为了研究表面环向裂纹对矿用钻杆性能的影响,基于弹性断裂力学理论对问题进行分析,对含有不同长度和深度环向裂纹共9根钻杆进行了静扭试验,得到了钻杆断裂扭矩和裂纹的开裂角。试验结果表明:在裂纹尺寸较小时(长10mm、深2.5mm),裂纹不易扩展;裂纹开裂角在10°左右,随着裂纹深度的增大开裂角有增大趋势;裂纹长度或深度中某一参数较大时,随着另一参数的增大,钻杆断裂扭矩急剧减小。使用有限元数值模拟方法再现了裂纹开裂前裂纹附近的应力分布情况,并得出结论。这些结论对钻杆的设计及现场事故处理具有指导意义。

In order to investigate the influence of surface circumferential crack on the performance of mine drilling rods, the problem was analyzed based on linear elastic fracture mechanics. Static torsion tests were carried out for 9 mine drilling rods, and the cracks under different lengths and depths were put on the surface of drilling rods in advance. The torque values of crack propagation and crack growth angle were obtained. The test results indicate that the crack is difficult to propagate when the size of crack is too small （length 10mm, depth 2. 5mm） ; the crack growth angle is about 10°, which rises with the increase of crack depth ; when the length （ depth ） of the crack is relatively large, the torque of crack propagation decreases sharply with increase of the crack depth （length）. Finally, the stress distribution before the crack propagation was obtained using finite element modeling. The stress decreases almost linearly on both sides of the crack from outside to inside, which suggests the crack will propagate from inner circle edge.