钻杆裂纹扩展是一个典型的不连续问题，采用常规有限元方法难以实现裂纹扩展过程的仿真模拟，而扩展有限元法（XFEM）是近年来发展起来的分析断裂问题的一种有效方法。在介绍了扩展有限元法的基本原理的基础上，建立了基于XFEM的含不同深度初始裂纹的5in钻杆在拉力和扭矩共同作用下的裂纹扩展模型。通过钻杆裂纹扩展过程的分析后发现，钻杆的初始裂纹深度小于1mm时，裂纹不易扩展，但初始裂纹深度超过2mm时裂纹会在相对较低的外载荷下扩展，且扩展面较大并与初始裂纹面存在一定夹角，最终造成钻杆断裂失效。通过对钻杆裂纹的扩展过程仿真模拟，展示了XFEM在钻具断裂失效分析方面的独特优势，并为这方面的研究提供了一种新方法。

Crack growth of drill pipe is a typical discontinuous problem. It is difficult to simulate with conventional finite element method and extended finite element method (XFEM) is developed in recent years for the problem. With the introduction of XFEM, the XFEM model of 5 inch drill pipe was proposed with different depth initial cracks under combined action between torque and tension. Based on the simulation, It is found that the smaller cracks is not easy to grow, whilst the crack of depth more than 2mm could grow under relatively lower external load and larger growth surface, eventually leads to pipe fracture failure. Through this simulation on crack growth of drill pipe, it is showed that the XFEM is appropriate in analysis of fracture failure.

国家自然科学基金资助项目（50774063）;国家重大专项资助项目(2008ZX05022-005-004HZ)