Enhanced microwave absorption and mechanical properties of conformal composite with gradient graphene honeycomb

Abstract This study aims to develop a novel conformal composite structure with integrated stealth and load bearing. Specifically, the stealth sandwich composite with graphene honeycomb (SCGH) was proposed and used as the electromagnetic (EM) window of overall structure. The multi‐layered honeycomb with gradient impedance was designed and prepared through the chemical self‐assembly process and the vacuum infusion process. The EM reflectivity at different incident angles was experimentally tested to reveal the absorption properties of the SCGH. The measured results show that the SCGH exhibits excellent stealth characteristics. Across the frequency range of 2–18 GHz, the reflection loss (RL) of the SCGH is less than −10 dB. The maximum RL of SCGH is −63 dB at 7.3 GHz. In addition, the SCGH is not very sensitive to the incident angle of EM waves. The uniform loading test was conducted on the overall structure with open window (SOW), and the deformation characteristics and typical damage modes are revealed. The local stiffness of the SOW was reduced by the open window, leading to significant deformation in the window corner areas. The primary damage mode under uniform loading is fiber fracture, occurring at the four window corners due to large deformation. This study provides reference and basis for structural design and performance analysis of conformal composite with integrated stealth and load bearing. Highlights Designed and prepared the composite structure with conformal window. Revealed the stealth performance and reflectivity at different incident angles of structure. Investigated the mechanical performance and failure mechanism of the structure.