An investigation of soft impacts on selected aerospace grade alloys based on Johnson-Cook Material Model

In aerospace industry, metallic alloys are regularly used to manufacture various components ranging from stabilizers to engine shafts. These components must withstand foreign objective damage (FOD), which includes bird strikes, hail, ice, or any metal or concrete debris from the runway. In this current research, some selected aerospace grade alloys, namely, Al-2024-T3, Al-7075-T6, Ti-6Al-4V, and Inconel-718, which are regularly used to build potential aircraft components exposed to bird strike (otherwise known as soft impact) phenomena, is numerically tested to investigate their ability to resist the collision under two different impact velocities (117 m/s and 147 m/s). Finite element explicit code Ansys is adopted to run the test cases. Johnson-Cook flow stress and damage parameters are selected to model the alloy materials while Mooney-Rivlin parameters are utilized to represent the Lagrange bird model. From the investigation, it is found that the Inconel-718 plate is the best candidate to resist the bird impact and further analysis reveals that it can withstand an impact velocity of 327 m/s without being penetrated. Apart from Inconel-718 alloy, both Al-2024-T3 and Ti-6Al-4V plates are found to be damaged at the impact velocity of 147 m/s, while Al- 7075-T6 is completely penetrated even at a lower impact velocity, 117 m/s. Finally, some recommendations and future research directions are suggested based on numerical outcomes.