Effect of Two Coatings on Impact Response and Compression After Impact Strength of Composite Laminates

ABSTRACT Composite laminates are particularly vulnerable to low‐velocity impacts, which induce internal damage and lead to significant strength reduction. This study presented the first investigation into the application of Polyisocyanate Oxazolidone (POZD) coatings on composite to enhance impact resistance. The effectiveness of POZD and Polyurea (PUA) coatings was evaluated through a series of impact tests at three energy levels (17, 32.5, and 50 J), followed by compression‐after‐impact (CAI) assessments. Both coatings significantly reduced damage area and suppressed crack propagation compared to uncoated specimens. Notably, they prevented weak zone formation at impact sites under low‐energy impacts and maintained superior CAI strength across all energy levels. Under 50 J impact conditions, the CAI strength showed the most significant variation. Compared to uncoated CFRP, the CAI strength of PUA‐CFRP specimens increased by 7.78%, while that of POZD‐CFRP increased by 15.27%. POZD‐coated laminates demonstrated optimal performance, exhibiting the smallest damage area and highest CAI strength values, establishing POZD as the superior protective coating for impact‐prone composite structures.