Evaluation of impact fatigue damage in glass/epoxy composite laminate

In the current study, experimental investigations are carried out to determine the response of glass/epoxy cross ply laminates to repeated low-velocity impact. The material response is evaluated in terms of damage progression with the number of impacts. Damage is evaluated by visual and SEM inspection. Damage parameter D is based on the evaluation of the loss of material bending stiffness and evolution of damage parameter is given versus number of impacts. Rectangular composite laminates of size 280 mm by 180 mm and nominal thickness of 5.4 mm are subjected to low-velocity impact fatigue loading at two energy levels (4 and 5 J). Delamination has been found as the main factor of increasing of damage parameter. Impact crater participate less to this increase at the beginning of live duration but has greater influence on D parameter evolution at the end. Experimental results indicate that the damage evolution versus number of impacts can be represented by “S” shape curve and thus indicates the importance of the first impacts.