连续管复合裂纹的应力强度因子有限元分析

Finite element analysis on stress intensity factor for composite cracks of coiled tubing

针对解析法计算连续管复合裂纹应力强度因子繁琐的问题,引入扩展有限元法(XFEM)进行分析。应用有限元软件ABAQUS计算不同裂纹角度对应的连续管Ⅰ,Ⅱ,Ⅲ型裂纹的裂尖应力强度因子KⅠ,KⅡ,KⅢ,分析了裂纹角度对应力强度因子的影响,并模拟得到了受单向拉伸载荷的连续管裂纹扩展的整个过程。研究结果表明:扩展有限元解与计算解很接近,验证了利用扩展有限元法计算复合型应力强度因子的有效性。随着裂纹夹角θ的增大,裂尖处KⅠ不断减小、KⅡ始终很小,可以忽略、KⅢ先增大后减小、总应力强度因子K不断减小。通过扩展有限元法计算出裂尖应力强度因子,可有效预测含裂纹CT80连续管的安全性。

Aiming at the problem that it is very tedious to calculate the stress intensity factor for the composite cracks of coiled tubing by using the analytical method,the analysis was carried out by introducing into the extended finite element method(XFEM).The stress intensity factor KⅠ,KⅡand KⅢfor the typeⅠ,ⅡandⅢcrack tip of coiled tubing corresponding to different crack angles were calculated by using the finite element software ABAQUS,then the influence of crack angle on the stress intensity factor was analyzed,and the whole process of crack propagation for the coiled tubing under the unidirectional tensile load was obtained by the simulation.The results showed that the solution of XFEM was very close to the calculation solution,which verified the effectiveness of calculating the composite stress intensity factor by using XFEM.With the increase of crack angleθ,KⅠdecreased continually and KⅡwas always very small at the crack tip,which could be ignored,while KⅢincreased first and then decreased,and the total stress intensity factor K decreased continually.The stress intensity factor of crack tip can be calculated by using XFEM,and the safety of CT80 coiled tubing containing cracks can be predicted effectively.