中文摘要：

钻柱涡动是钻柱失效的主要原因之一。应用有限元方法，仿真了空气钻井时斜直井眼中带牙轮钻头钻柱的动力学特性，比较了空气钻井和钻井液钻井条件下钻柱的涡动、变形以及动态应力状况，探讨了空气钻井钻柱失效的动力学机理。结果表明，钻柱在不同时刻的动态应力与静力学条件下计算的结果有宏观上的一致性，空气钻井时钻柱的应力波动较钻井液钻井的要大，钻柱涡动更加频繁。

英文摘要：

The whirl is the main reason of drill string failure. Applying finite element method, the dynamic characteristics of drill string with cone bit in straight hole were simulated, and the whirl, deformation and the dynamic stress in air drilling were compared with the ones in drilling fluid drilling. In addition, the dynamic mechanism of drill string failure in air drilling was discussed. The results show that there is a consistency of the variations for stress of drill string in general between dynamic and static, but stress fluctuation of drill string in air drilling is much larger and the whirl is much more frequent than the ones in drilling fluid drilling.