Effect of PEEK on interfacial damage propagation behavior of ceramic/FRP composites subjected to high-velocity impact: An experimental and numerical study

In recent years, the extensive application of Ceramic Composite Armor Systems (CCAS) in defense engineering has brought increasing attention to impact-induced damage. Existing mitigation strategies often lack sufficient viscoelasticity and material compatibility with the polymer adhesion layer for optimal stress wave management. To address these problems, this work proposed a novel strategy by inserting a Polyether-Ether-Ketone (PEEK) interlayer at critical interfaces. Through the ballistic tests on a representative Al₂O₃/Carbon Fiber (CF)/Aramid Fiber (AF) composite armor, this work demonstrated that the PEEK interlayer significantly suppresses debonding/delamination by redirecting energy dissipation from interface damage to concentrated backup plate deformation. A sophisticated Finite Element Analysis (FEA) reveals that this suppression stems from PEEK's stress-wave attenuation via viscoelastic damping and impedance matching, which delays wave transmission and reconstructs the energy dissipation path. Furthermore, it is indicated that increasing the thickness can enhance its inhibitory effect, and its influence on damage suppression follows a strong quartic polynomial relationship. It is also revealed that the strategic incorporation of a viscoelastic PEEK interlayer is a manufacturable and effective approach to enhance multi-impact potential, establishing a generalizable design principle for composite armors through tailored interfacial wave manipulation.