High‐Velocity Ballistic Impact Performance of FFF Printed PEEK With Different Infill Patterns

ABSTRACT This study presents a combined experimental and numerical investigation of fused filament fabrication (FFF)‐printed polyether ether ketone (PEEK) plates subjected to quasi‐static and high‐velocity impact loadings. Izod impact, quasi‐static punch‐shear (QS–PS), and high‐velocity projectile impact tests were conducted on specimens with different infill patterns, namely line, grid, cubic, and hexagonal configurations. High‐velocity impact experiments were performed using a two‐stage gas gun at an impact velocity of 100 m/s. Infill architecture influences quasi‐static and low‐rate impact performance. The hexagonal pattern exhibited the highest Izod impact strength (ca. 24 kJ/m 2 ) and punch‐shear strength (ca. 12 MPa), demonstrating improved load distribution and energy absorption capability. Under high‐velocity impact, infill geometry becomes less influential, indicating comparable ballistic responses. This reduced sensitivity to infill pattern is attributed to rapid stress‐wave propagation and extremely short interaction times, which limit progressive deformation within the internal structure. Finite element simulations using a solid PEEK model further support these findings, showing similar stress distributions and penetration behavior across all configurations. The results demonstrate that while infill geometry plays a critical role under quasi‐static loading, its effect diminishes under high‐velocity impact, where the response is predominantly governed by the intrinsic material behavior of PEEK.