Experimental and numerical study on failure behaviors of composite grid stiffeners under tensile and flexural loading

Experimental and numerical studies are carried out to investigate the failure behavior of grid stiffeners under tension and flexural loadings. The grid stiffeners with three different typical layup schemes at the intersection were manufactured and tested. A 3D anisotropic damage model based on continuum damage mechanics is developed to modeling the progressive failure behaviors of the grid stiffeners. Besides, the digital image correlation (DIC) technique was adopted to capture the complex deformation and failure process. Results show that introducing discontinuous plies at the intersection could change the failure mechanism and hence improve the mechanical performance of the grid structure. The tensile and flexural strength are improved by 21% and 23% respectively by properly introducing 25% of discontinuous plies at the intersection. This work provides insights on the failure mechanisms of the composite grid stiffeners, and results can be further used towards the optimization design of the grid structure.