Mechanism of the Influence of Interlayer Mechanical Properties on the Ballistic Performance of Transparent Armor

ABSTRACT The ballistic performance of transparent glass armor is significantly influenced by the mechanical properties and thickness of polyurethane (PU) adhesive interlayers. This work develops an experimental method to measure interlayer tensile and shear failure stresses. Results show that the polycarbonate (PC)/PU interface exhibits higher tensile strength (13.245 MPa) than the glass/PU interface (11.490 MPa), while the trend reverses for shear strength (13.341 vs. 6.080 MPa). Under high‐velocity impact, the PU layer deflects through‐thickness cracks and impedes wave propagation. Simulations reveal that as bond strength increases from 5 to 15 MPa, the debonding area decreases from 0.28 to 0.07 m ² , yet crack density in the glass layers increases. Increasing PU thickness amplifies energy absorption and cushioning effects. From an acoustic impedance perspective, the adhesive layer improves stress‐wave attenuation. Interfacial behavior is thickness‐sensitive: thin layers constrain deformation and aggravate damage, while thick layers promote energy dissipation, shifting design thinking toward coordinating the interface–bulk energy dissipation chain.