The tangency point of Bottom Hole Assembly is located at where the drill string just touches the wall of the borehole, and the contact force is zero here.

在计算底部钻具组合的受力和变形时，以前一般都是按弯矩为零的条件来确定其上切点的位置。

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Numerical simulation shows that the new method is more effective for the drill-string assembly unsuitable to be simplified as a torsion pendulum.

数值模拟结果表明，对不适于简化为扭转摆的钻柱系统，采用基于钻柱扭转杆模型的新方法进行设计可以取得相对较好的减振效果。

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