Effect of coating thickness on ballistic impact behavior of aluminum foam/polyurea reinforced composites

Abstract

The poor impact resistance of aluminum foam restricts its wide application in advanced engineering structures while reinforcing phases and coatings are effective methods to improve its impact resistance. The ballistic impact resistance can be optimized by adjusting the mixing ratio of composite layers and coatings, but this requires a systematic exploration of the reinforcement mechanism and failure mechanism. In this paper, the ballistic impact behavior of aluminum foam/polyurea composites against cylindrical fragments is systematically investigated. Hybrid specimens with different coating positions and mixing ratios were designed, tested, and compared. The results show a strong correlation between coating thickness and ballistic impact performance. When the coating thickness increases but does not exceed the critical value, the energy absorption capacity of the composite is enhanced. On the contrary, the opposite result occurs when the coating thickness exceeds the critical value. This phenomenon is related to the support effect of the coating, which can significantly affect the enhancement of the reinforcing phase. Further analysis shows that the support effect and the enhancement together dominate the different impact damage modes.