Damage mechanism and residual strength at different impact locations for composite bonding scarf repairs

Composite scarf repair has been widely applied as a high efficiency choice for force transferring in aircraft structure repair. The damage tolerance and resistance to low velocity impact are significant for structure design especially for primary load-bearing structures. Some literature studied impact damage and resistance for scarf topology repairs or joints. However, it is not clear that which location in bonded area is the most sensitive to the impact load. The impact location effect on impact damage mechanisms and capacity of tension after impact (TAI) are studied in this paper. Central point in bonded zone has the strongest influence on impact damage. The scarf adhesive film fractured from the feather tip of the back side and oriented to the weakest material. The load capacities of tension after impact at different locations coincide with the adhesive damage area ratio. The finite element model based on CZM (Cohesive Zone Model) is built. And the simulation results validate that central location has the most sensitive characteristic to impact damage and TAI capacity.