圆柱壳结构外压弹塑性稳定性问题的半解析有限元法

本文综合考虑了几何、物理双重非线性因素的影响,对圆柱壳结构在承受外压作用下发生失稳屈曲进行了研究。几何方程采用大位移的应变位移关系,物理方程采用弹塑性分析的应力应变关系,导出了圆柱壳单元弹塑性分析的切线刚度矩阵。计算中,为了追踪失稳屈曲完整的平衡路径,在位于极值点邻域内的每一增量步中,我们采用控制弧长约束下的增量一迭代法进行计算,使计算效率大大提高。

Semi—Analy tical Finite Element Method on Elastoplastic Stability Problem of Cylindrical Shell under External Pressure

Taking the influence of material and geometrical non-linear factor into account, this article researches into stability buckling of cylindrical shell under external pressure. In this paper, Semi-analytical displacement model is stated, and large deformation strain-dis- placement relation is adopted in geometrical equations and elastoplastic stress-strain is adopted in physical equations. Non-linear tangential stiffness matrix of cylindrical shell el- ement is derived. In the Calculation, the linear elastic theory is first used to work out a min- imum iteration range for the following stability Calculation, and then the increment-iteration method is used to trace the complete equilibrium curve. In order to avoid the strangeness of tangential matrix in the neighbouring region of maximum, are length--Control method is used for iteration in every increment step, which greatly raises the calculation efficiency.