Abstract: Based on the modern damage mechanics research，aiming at the gas drilling string frequent fracture failure，the drill string damage evolution process was analyzed. The gas drilling damage fatigue life prediction model of the drill string was established. The gas drill string damage fatigue life model was the main factors influencing the fatigue life of drill string. And damage gradient was introduced to explore the relationship among axial load, injury tolerance and strain. According to the theory and case analysis, the relationship between injury tolerance and strain is going through a change from space period to quasi periodic with the axial load increasing. Meanwhile, damage localization occurs that lead to drill string fatigue failure. 

Key words: Gas drilling,    ,  String,    ,  Constitutive relation,    , Damage degree,    , Damage evolution,    ,  Fatigue life

摘要： 针对气体钻井钻柱频繁断裂失效问题,以现代损伤力学研究为基础,分析钻柱损伤演化过程,建立气 体钻井钻柱损伤疲劳寿命预测模型。由钻柱损伤疲劳寿命模型得出损伤度是影响钻柱疲劳寿命的主要因素,引入损伤梯度并进一步通过算例研究钻柱所受轴向载荷、损伤度及应变之间的关系。根据理论与算例分析可得,随着轴向载荷增大,损伤度与应变逐步由空间周期关系转变为类周期关系,出现损伤局部化,导致钻柱的疲劳失效。

关键词: 气体钻井,    , 钻柱,    , 本构关系,    , 损伤度,    , 损伤演化,   , 疲劳寿命