First , higher - order shear deformation theory and reddy ' s simplified higher - order shear deformation theory of the flat shell is adopted to obtain the buckling governing equations . then the geometric nonlinear theory and the geometric and material dual - nonlinear theory with shear effects are introduced ( the buckling governing equations are get ) . the simplified geometric nonlinear theory and the small defection theory are discussed as emphases 首先采用扁壳高阶理论及reddy型简化高阶剪切变形扁壳理论，得到了屈曲基本方程，然后介绍了考虑剪切的几何非线性理论及材料几何双重非线性理论(得到了屈曲基本方程) ，重点讨论了简化的几何非线性理论及小挠度理论。
