Buckling of elastoplastic functionally graded cylindrical shells under combined compression and pressure

Buckling behaviors of elastoplastic functionally graded material cylindrical shells under combined axial compression and external pressure are investigated with classical shell theory. The material properties vary smoothly through the thickness, and a multi-linear hardening elastoplasticity is used in the analysis. By extending TTO model of functionally graded materials into J2 deformation theory, the elastoplastic constitutive relation of FGMs is founded. The buckling governing equations are solved by Galerkin method, and the expression of the critical condition under combine in-plane loads is given. Numerical results are given through an iterative procedure between the prebuckling state and the critical condition. Numerical results give the interactive curves of the stability regions and the exact elastoplastic interface of the materials. It is interesting to find that, material plastic flow is of significant effects on the stability region, and the effects of the constituent distribution and the elastoplastic material properties are discussed as well.