再论“钻头处的边界条件”

FURTHER DISCUSSION ON THE BOUNDARY CONDITION AT THE BIT

由于现在人们对底部钻具组合的受力和变形分析研究仍主要处于静态阶段 ,认为在纯静态的分析中加入一点动态的影响 ,即考虑钻头在钻进时弯矩不断变化的事实 ,将钻头处的边界条件按固支和铰支各计算 1次 ,最终结果取这 2次结果的平均值 ,这可能比只按固支或铰支所得结果更接近真实值。

The mechanical analysis of bottom hole assembly is still in the phrase of static study, and some dynamic factors should be considered, i.e., calculating the bit boundary condition twice by taking the bit as an articulated support and an immovable support separately, based on the fact that the bending moment of bit is continuously changing, and then average the two results. The result of this method may be more reliable, as compared with the result obtained by taking the bit as just an articulated support or an immovable support.