Radar stealth and post-impact compression behavior of chain-stitched nickel-plated glass fiber/epoxy composites under low-velocity impact

Abstract

Herein, a nickel-plated glass fiber/epoxy radar-absorbing structure with chain stitching was proposed to enhance its resistance to impact-induced damage, which can compromise both stealth performance and structural integrity. A low-velocity impact test was conducted to assess damage size, radar-absorbing performance, and residual mechanical properties. C-scan and X-ray micro-computed tomography revealed that the stitched specimens sustained smaller damage areas than the unstitched specimens, with the latter exhibiting through-thickness damage at an impact energy of 41.6 J. Scanning return loss measurements confirmed that such damage compromised the absorption performance, whereas stitching mitigated this effect. Compression after impact testing showed that the failure load of the unstitched specimens was 5%-7% lower than that of the stitched specimens. The results indicate that chain stitching mitigates impact damage while maintaining radar-absorbing efficiency and residual mechanical properties under impact loading, providing initial evidence of its potential as a reinforcement strategy for radar-absorbing structures. Still, challenges remain regarding parameter optimization, fiber distortion, resin flow, and durability, which should be addressed in future work to enable reliable application in multifunctional aerospace structures.