Effect of strength matching on failure characteristics of polyurea coated thin metal plates under localized air blast loading: Experiment and numerical analysis

A favorable strength matching can be very beneficial for improving the performance of polyurea coated thin metal plates to resist blast loads. This study made an attempt to elucidate the effects of material and interface strengths, including steel and polyurea strengths, and interface normal (NFLS) and shear strengths (SFLS), on the failure characteristics of polyurea coated steel (PCS) plates under localized air blast loading. First, air blast experiments were conducted to identify the deformation and failure of PCS plates with different steel strengths. Subsequently, elaborative numerical simulations were performed to analyze the dynamic response and energy absorption characteristics of PCS plates. Finally, the effects of material and interface strengths on the failure characteristics of PCS plates were numerically evaluated. The results show that the kinetic energy of polyurea fragments significantly contributed to the total energy absorption of polyurea backing layer (PBL) that failed due to spalling. The steel strength had a significant effect, whereas the polyurea and interface strengths had marginal effect on the deformation of front steel layer (FSL). Increase in polyurea strength led to a dramatic decrease in the energy absorption proportion (EAP) of kinetic energy of polyurea fragments, but this EAP slightly varied by changing the steel strength or interface strength for PBLs that failed by spalling. The dominant energy absorption mechanisms of PBLs changed with the variation in steel and polyurea strengths, but did not vary with interface strength, including NFLS and SFLS.