Numerical investigation of stiffened composite panel into buckling and post buckling under combined loading

Akay, Erkan
This thesis presents the investigation of buckling and post buckling behaviour of stiffened thin walled laminated composite aerospace structures subjected to combined in-plane axial and shear loadings. Due to the fact that the state of stress developing especially in the post-buckling stage is quite complicated under the combined loading, the necessary computational model is usually based on Finite Element Modelling (FEM). In this study, after verifying the FEM methodology and completing the sensitivity studies, the buckling and post buckling phenomenon are examined in order to see the effects of shear loading beside the axial compressive loading on a stiffened composite panel via linear and nonlinear analyses. The results show that under combined in-plane loading of a stiffened panel, additional shear loading beside the axial loading has an influence on the axially critical buckling load capability of the structure depending on the characteristic of the structure like ply orientation.