钻柱纵向振动仿真分析

国仙外在研究钻柱振动时都把钻柱下端当作铰支，假设激振源为周期性的，偏离实际。从建立符合实际的下端边界条件入手，着重研究了钻柱的纵向振动。用有限单元法，求出整体质量、整体刚度，整体阻尼矩阵采用的是比例阻尼矩阵，利用牛顿法得到钻柱的振动方程，另外通过钻头与岩石的相互作用模型得到了起初的钻柱下端边界条件，并利用Ｈｏｕｂｏｌｔ数字解法模型求解了振动微分方程。根据上述模型编制了用于分析钻柱纵向振动的计算机仿

SIMULATION OF DRILL STRING'S LONGITUDINAL VIBRATION

At present,the end of drill string (DS) is simplified as a hinge in FE analysis and the excitation is assumed periodic. This paper emphasizes the longitudinal vibration of DS by modelling the lower end of DS with actual boundary condition. The structural mass matrix and stiffness matrix are obtained,from which the proportional damping matrix is also obtained. The real boundary condition of the lower end of DS is obtained by studying the interaction between the roller cone bit and the rocks. The vibration equation is dissolved by the HOUBOLT technique, a numerical solution method. A simulation software was developed according to the above vibration model. A lot of simulating experiments have been carried out. Some meaningful results are obtained which will guide drilling operations.