Ballistic performance of aluminum alloy plates with polyurea coatings for high-speed train structures

Abstract

Polyurea coatings have been widely promoted in explosion and ballistic impact protection applications due to their excellent hyper-elasticity performance. In rail transportation, high-speed trains face potential impact threats from track ballast, which can affect the strength performance of the base material. To address these challenges, we examined the ballistic performances of aluminum alloy plates with polyurea coatings under large-scale impact (>30 mm). Four different configurations of target plates were investigated: A, P-A, A-P, and P-A-P. We fabricated samples and performed dynamic impact tests using an air cannon system to demonstrate the feasibility. Results show that ballistic performance is significantly improved by applying polyurea coatings on aluminum alloy plates. In particular, the growth rate of limit velocity of configuration A-P, P-A, and P-A-P to that of configuration A are 5.5 %, 19.4 %, and 22.8 %, respectively. The enhancement mechanism was further uncovered through stress wave propagation analysis and lateral energy diffusion effect. Explicit formulas for predicting the limit velocity and residual velocity were derived and demonstrated with reasonable accuracy over a wide range of parameter spaces. The observed enhancement in ballistic performance through polyurea coatings on aluminum alloy plates offers promising ways to design and implement more resilient and impact-resistant high-speed train structures.