柱壳结构弹塑性稳定性分析的半解析有限元法

对圆柱壳结构在承受外压作用下发生失稳屈曲的研究,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变矩阵。计算中,为了追踪失稳屈曲完整的平衡路径,在位于极值点邻城内的每一增量步中,我们采用控制弧长约束下的增量——迭代法进行计算,使计算效率大大提高。

SEMI-ANALYTICAL FINITE ELEMENT METHOD ON ELASPLASTIC STABILITY ANALYTICAL OF CYLINDRICAL SHELL UNDER EXTERNAL PRESSURE

This artical researches into stability bulkling of cylindrical shell under external pres-sure. In this paper, semi-analytical displacement model is stated, and iarge deformation strain-displacement relation is adopted in geometrical equations and elastoplastic stess-strain is adopted in physical equations. Non-linear tangential stiffness matrix of cylindrical shell el-ement is derived. In the calculatoin, the linear elastic theory is first used to work out a mini-mum 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 tangentical matrix in the neighbouring region of maximum, Arclength-control Method is used for iteration in every in-crement step, which greatly reaises the calculation efficiency.