MWCNT ‐Modified Cellulose Interleaved Multifunctional CARALL ‐Like Composites for Real‐Time Impact Detection and Electromagnetic Interference Shielding

ABSTRACT Carbon Reinforced Aluminum Laminates (CARALL) are frequently exposed to impact loads during service. Effective structural health monitoring (SHM) is therefore essential for detecting and assessing impact‐induced damage in real‐time. Furthermore, even low‐velocity impacts can compromise the electromagnetic interference (EMI) shielding performance of components. In this study, cellulose‐based sensing papers were fabricated using the traditional paper‐making method, incorporating multi‐walled carbon nanotubes (MWCNT) to impart electrical conductivity. Cellulose papers with two cellulose areal densities (160 and 210 g/m ² ) and three MWCNT concentrations (5%, 7%, and 9% by weight) were placed between the aluminum and carbon fiber layers of the CARALL‐like composites. Low‐velocity impact tests were performed on all CARALL‐like specimens, with SHM signals recorded throughout the tests. After the impact tests, failure analysis and EMI shielding performance were investigated. The results demonstrated that the composite—incorporating cellulose paper with 210 g/m ² of cellulose and 9 wt.% MWCNT—experienced a nearly sevenfold increase in resistance change during damage monitoring. Additionally, the total shielding efficiency was 60.0 dB, increasing the shielding effectiveness reflection by 50%. This demonstrated that it exhibited the most effective combination of SHM sensitivity and EMI shielding performance.