Realization and characterization of broadband absorbing FRCM via microwave curing process

Abstract Fiber-reinforced composite metamaterials (FRCMs) represent a class of emerging structural absorbing materials for load-bearing components in aerial combat aircraft, combining wave absorption capability with bearing property to enhance survivability. FRCMs are typically fabricated by thermal curing, where inevitable temperature inhomogeneities in large components intensify thermal mismatch and asynchronous curing between metamaterials and composites, resulting in defects and deformation that compromise load-bearing and stealth performance. Therefore, this study optimizes the design of FRCMs to achieve broadband stealth performance (4–18 GHz) with enhanced absorption at 2.45 GHz. By adopting microwave curing instead of conventional thermal curing, uniform isothermal heating is realized, enabling efficient and high-quality fabrication. The results demonstrate that the designed square-loop resonators (SLRs) achieve efficient microwave absorption through electromagnetic resonance at 2.45 GHz, enabling uniform heating of FRCMs, with the in-plane temperature difference controlled within 5℃. Furthermore, multilayer split-ring resonators (SRRs) are constructed, which exploit destructive interference between the layers to achieve broadband stealth functionality across the 4.6–18.0 GHz range, with an arithmetic average absorbance exceeding 90%. Microwave curing experiments are subsequently conducted, revealing that microwave curing significantly improves interlaminar shear strength (ILSS) compared with FRCMs fabricated by thermal curing, with an increase of 37.73%, achieving integrated structural-functional manufacturing of FRCMs.