Compression behavior of stitched stiffened panel with a clearly visible stiffener impact damage

Damage tolerance of stitched stiffened composite panels with clearly visible impact damage to a stiffener was investigated. Two-blade stiffened composites panels were fabricated using resin film infiltration technique. The effects of stitching are assessed using unstitched, selectively stitched and fully stitched panels. Impact damage was induced using a drop weight impact of 30 J from the skin side over the stiffener. The experimental results indicate that selectively stitched panels showed 14.4% improvement in compression after impact strength compared to both the unstitched and fully stitched panels. Post-buckling finite element analysis was performed to predict the buckling and failure strengths of these stiffened panels.