Analytical and experimental investigation of high velocity impact on foam core sandwich panel

In this article, a new analytical model is presented to simulate the behavior of a composite sandwich panel against the ballistic impact of a blunt head projectile. The analytical model proposes a multi‐stage perforation process based on experimental observations. Each stage is simulated by an individual mass‐spring model and the projectile's equation of motion is derived. In every step of the theoretical model, the energy balancing between the kinetic energy of the projectile and the energy absorbed by the target is considered. Significant energy‐absorbing mechanisms which accounted in the model are plugging of the front skin, delamination of composite laminates of the skins, debonding between skins and core, local core crushing ahead of projectile and partial penetration, core fracture and fiber fracture of the rear skin. Also, some strain energy is absorbed because of the global deformation of the target. Since the foam core failure consists of crushing and fracture, this model can calculate the residual velocity in every situation whether the foam is stiff and hard to crush or soft and crushable. In addition to the theoretical analysis, some experiments are carried out to validate the analytical predictions. A good agreement is confirmed between analytical and experimental results. POLYM. COMPOS., 40:2258–2272, 2019. © 2018 Society of Plastics Engineers