Effects of debonding defects on the postbuckling and failure behaviors of composite stiffened panel under uniaxial compression

Effects of stiffener debonding defects on postbuckling responses and failure behaviors of composite stiffened panels which have extensive applications in aerospace structures attract significantly increasing attention recently. Aiming to this problem, a series of nonlinear analyses comprehensively accounting for multiple failure modes including intra- and inter-laminar damage in composite laminates, adhesive layer damage between stiffeners and skin, as well as buckling and postbuckling responses were carried out via a numerical model. This numerical model is combined with a progressive damage model and a cohesive zone model, and has been validated to be effective for predicting the postbuckling and failure responses of composite stiffened panels. Seventeen computational cases with different parameters including debonding sizes and positions which can affect buckling and postbuckling responses were conducted. It follows that debonding defects can change postbuckling deformation modes of stiffened panels and their development paths, which induce different degrees of inflection and distortion in structures, and change failure behaviors as well as the failure process of composite laminates, and further weaken the ultimate failure strength of the whole composite stiffened panels.