底部钻具组合三维静力分析的新方法

利用二阶埃尔米特插值函数把空间梁单元的结点自由度由６个扩充到８个，使井眼曲线的二阶导数连续，提高了计算精度。在１６自由度梁单元形函数矩阵和应变分析的基础上，推导了１６自由度梁单元的线弹性刚度矩阵、线弹性几何刚度矩阵和单元结点等效载荷列阵。考虑轴向力的非线性影响，应用该方法对底部钻具组合的钻头侧向力进行了线性分析。计算结果表明，考虑二阶导数的影响，可以提高计算精度。

A NEW METHOD FOR 3D STATIC ANALY SIS OF BOTTOM HOLE ASSEMBLY

When the nodal degrees of freedom in beam element increase from 6 to 8 by the use of Hermit interpolation function, the second derivative for expressing hole curvature becomes continuous, and the calculation precision is improved. The shape function matrixes and linear strain of the 16 degree of freedom beam element are analyzed, and the linear elastic element stiffness matrix, geometrical stiffness matrix and the nodal equivalent load matrix are deduced. This method is applied to analyze the lateral force of bit linearly with the nonlinear axial force being considerated. The computation precision can be enhanced with the consideration of second derivative.