Experimental research on low-velocity impact and residual compressive strength of composite stiffened panels

Drop hammer low-velocity impact(LVI) tests on composite stiffened panel were carried out. Impact support bracket was designed based on specimen configuration, and effect of bracket pitch on impact damage was studied. Impact tests with the same energy on three typical positions of specimen were carried out to obtain the damage appearance. Compressive tests were conducted and test results of damaged specimens and undamaged ones were compared to analysis the effect of impact position on the compressive performance of the structure. Test results show that, with the same impact energy, the smaller the bracket pitch is, the severer the impact damage is. With the same impact energy of 50 J, damage on the stiffener skin is almost invisible, and damage on the skin between stiffeners is clearly visible, while impact on stiffener edge skin can result in debonding of the stiffener flange. Impact damage can slightly reduce the buckling load of the structure. The impact damage on the skin between stiffeners or on the stiffener skin has little effect on the compressive performance, while impact on stiffener edge skin can induce local buckling of damaged skin, and it has a notable effect on the failure pattern as well as the ultimate strength of the structure.