Self-Excited Vibrations of Drillstrings

所提出的分析研究的目的是为预测各种土掘进作业中使用的钻头的动力稳定性极限提供技术基础。在分析钻头运动和确定动态稳定性极限时，将考虑轴向、扭转和横向模式的综合影响。模态耦合效应的研究将表明哪些振动模态是关键的，并导致改变钻井系统结构稳定性的实用方法。从这项研究中获得的知识将为减少钻柱失效和提高钻速提供技术指导。

The objective of the proposed analytical research is to develop a technical basis for predicting the limit of dynamic stability of drill bits used in various earth boring operations. The investigation will incorporate the combined effects of axial, torsional and lateral modes in the analysis of bit motion and in the determination of the limit of dynamic stability. A study of the effects of mode coupling will show which modes of vibration are critical and lead to practical methods of changing the structural stability of the drilling system. The knowledge gained from this research will provide a technical guidance for reducing drillstring failures and increasing penetration rate.