Effects of stiffener geometric parameters on the buckling and post-buckling response of composite I-stiffened panels

The buckling instability and post-buckling carrying capacity are major concerns in the engineering design of composite stiffened panels and are influenced by a series of design parameters. This work investigated the rule and mechanism of the stiffener flange widths effects on the buckling instability and post-buckling response of composite I-stiffened panels under axial compression. With the compression experiments, the buckling instability and post-buckling response of the composite I-stiffened panels were obtained and further used in the validation of the finite-element (FE) model. A parametric study was then implemented in analyzing the effects of stiffener flange widths on the structural buckling instability and post-buckling response. The results indicate that skin-stiffener debonding and intra-laminar damage are the main failure modes. The structural buckling instability, carrying capacity and failure behavior are sensitive to the parameters of stiffener flange widths. The bottom flange width w(b) linearly affects the critical buckling load, but has no effects on the buckling mode. The top flange width w(t) simultaneously affects the critical buckling load and buckling mode, and an obvious buckling mode change occurs around a critical w(t) value. Both the bottom and top flange widths affect the structural damage process, failure mode and carrying capacity obviously.