Investigation of scarf-patch-repaired radar-absorbing composite using circuit-analog absorbers subjected to low-velocity impact loads

This study quantitatively evaluated the changes in the electromagnetic-wave-absorption performance of a circuit-analog (CA) absorber based on the applied impact energy. An electromagnetic simulation was employed to design a CA absorber with superior absorption efficacy within the X-band (8.2–12.4 GHz) spectrum. Based on this design, a CA absorber was fabricated using glass-fiber-reinforced plastic and a periodic pattern sheet (PPS). The damage to the CA absorbers was simulated through low-velocity impact tests at various energies, and their electromagnetic-wave-absorption degradation was quantified via return loss measurements. A scarf-patch repair method for the CA absorber was developed and applied to repair damaged absorber with the aim of reinstating their absorption performance, which was deteriorated by damage. Absorption performance evaluations of the repaired absorber confirmed that the proposed repair method can substantially restore the absorption performance. Additionally, simulations of the proposed repair method were used to enhance the understanding of the effects of the pattern mismatch and use of external ply within the PPS at the boundary line, which influence the effectiveness of the repair process.