Design of aircraft composite structures against ballistic impact threats

The technological advancements in the defense sector today have introduced new challenges regarding the safety and durability of military aircraft. In this context, the design of aircraft structures against high-kinetic-energy ammunition has become a significant area of research and development. Especially, large-caliber ammunition, such as the 12.7x99 AP listed in the MIL-PRF-46103E standard, poses a serious threat to the safety of aircraft against ballistic threats. Technical ceramic and composite materials (high-performance fibers and polymers that hold them together) used in composite aircraft armor structures are much lighter than traditional metal armors. This helps aircraft gain greater maneuverability, reach higher speeds, and improve fuel efficiency. Due to their high hardness, ceramic materials enable the fragmentation of large-caliber ammunition, converting it into shrapnel with lower kinetic energy, while composite materials stop these fragments with reduced kinetic energy by utilizing their high energy-absorbing capacity. In this study, a finite element model capable of predicting the deformation occurring at the moment of impact has been developed to design structures that are both resistant to ballistic impacts and lightweight. The accuracy of the material models, obtained through material characterization tests and literature data, was validated for each material through controlled ballistic tests to ensure that finite element analyses closely reflect reality. Under this study, finite element models of composite aircraft armors were developed using LS-DYNA software. Based on the finite element model data, an optimized composite aircraft armor for the 12.7x99 AP ammunition threat was produced, and V50 tests were conducted.