折叠结构几何非线性分析

本文提出了一种推导折叠结构宏单元刚度矩阵的新方法，即在所假设普通单元位移模式的基础上直接引入位移约束条件，得到宏单元的形函数矩阵，进而给出宏单元的力与位移间关系。利用该思路，文中简捷地推导出剪式单元三节点梁大位移小变形的几何非线性切线刚度矩阵，并给出了线性刚度矩阵的显式。算例表明，分析折叠结构承载能力和自稳定结构的展开或收纳过程，考虑几何非线性的影响是必要的。

Nonlinear formulation for foldable structures

Foldable structures are increasingly attracting to engineers. A new technique to formulate stiffness matrix of macro\|elements for foldable structures is developed in this paper. A large\|displacement geometrically nonlinear stiffness matrix formulation of uniplets of pantograph is also derived using this technique. Numerical examples show geometrical nonlinearity should not be negligible for deployable structures when analyzing load bearing capacity of deployable structures and deployment process of self\|standing structures.