Experimental investigation of Buckling after impact strength of grid stiffened composite panels

Composite lattice structures are widely used in the aerospace, automobile and marine industries due to their benefits such as high stiffness and strength with light weight. In this study buckling strength after impact of grid stiffened composite panels was investigated experimentally. For this purpose, grid stiffened composite panels with iso-grid reinforced lattice and three types of skin thickness of 6, 12 and 18 layers were designed, fabricated and tested. E-glass fibers and epoxy resin was used for both ribs and skin. At first, the specimens were subjected to a low velocity impact and then the buckling test was carried out. From results it is concluded that with increasing the thickness of skin, failure mechanisms such as fiber breakage, delamination, matrix cracking consumes more energy. But, by considering the weight, the buckling strength per weight of the specimen was maximum for the specimen with 12 layers for skin. More explanation about failre mechanisms are included in the manuscript.