应用DQE增量迭代法分析斜直井内管柱的非线性屈曲
Nonlinear Buckling Analysis of Tubular in a Deviated Well with Differential Quadrature Element Incremental Iteration Method
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摘要: 基于斜直井内管柱屈曲的平衡微分方程,构建DQE (Differential Quadrature Element)增量迭代法,对斜直井内管柱的非线性屈曲进行计算.通过与有限元的计算结果对比,验证方法的正确性.DQE法方法简单、易于实施,计算量少、精度较高,所得到的螺旋屈曲计算结果与实验结果吻合,最大井壁约束力随上端载荷的增加而增大.对于工程中比较长的受压段管柱,其屈曲是一个局部非线性稳定性问题,屈曲首先从下端开始发生,随着上端载荷的增加,逐渐向上扩展;上端边界条件对下端局部屈曲无明显影响.Abstract: Equilibrium equations of tubular in a deviated well are presented.A differential quadrature element(DQE)incremental iteration method is established to analyze nonlinear buckling of tubular in a deviated well.The method is verified with result of finite element method.It exhibits advantages of easy implementation,low computational cost and higher accuracy.Helical buckling by DQE agrees well with experimental data.The maximum constraint force increases with increasing of upper end load.It is found that the buckling of long tubular is a local buckling problem.The buckling starts from the lower end and propagates upward with increasing applied load.Boundary conditions at upper end have little influence on local buckling of lower tubular.