Electromagnetic shielding properties of impact damaged carbon and hybrid carbon and glass fibre reinforced polymer composites

Although the investigation of electromagnetic shielding properties of carbon fibre reinforced composites has increased over the last years, the topic of electromagnetic shielding durability received relatively little attention. The aim of this study was to systematically examine the effect of low velocity impact damage on the shielding effectiveness (SE) of continuous carbon and hybrid carbon/glass fibre reinforced polymer composites with various lay-ups. The SE measurements were carried out in a high frequency range (26-42 GHz) using free-space method with focusing lenses. It was observed that when the carbon fibre splitting occurred on the bottom carbon fibre ply oriented parallel to the incident electric field, the SE was noticeably reduced. Adding glass fibre plies with higher, compared to carbon fibres, strain-to-failure improved the impact resistance and thus delayed the threshold for SE reduction. Overall, it is demonstrated that, due to the synergistic effects, properly designed hybrid carbon/glass fibre composites can be used for lightweight electromagnetic shielding structures, whose shielding properties are maintained even after sustaining a mechanical damage.