Multifunctional Titanium-Carbon Fiber Metal Laminates for next-Generation Automotive EMI Shielding: The Role of Polyimide Veil Interleaving

Abstract

As the automotive industry shifts toward electric vehicle (EV) architectures and autonomous driving systems, there is an urgent demand for multifunctional structural materials that offer both superior crashworthiness and high-frequency electromagnetic interference (EMI) shielding. While fiber-reinforced polymers (FRPs) facilitate lightweighting, their inherent brittleness and limited shielding capabilities often necessitate hybridization. This study investigates the synergistic integration of Ti-6Al-4V titanium alloy sheets and unidirectional carbon fiber plies in a 3/2 Fiber Metal Laminate (FML) configuration. To address interlaminar delamination and enhance functional performance, neat thermoplastic polyimide (PI) veils were incorporated as interleaves. The EMI shielding effectiveness (SE) of the fabricated FMLs was rigorously characterized in the X-band (8.2–12.4 GHz). Results indicate that the PI veil-integrated FMLs achieved a SE exceeding 30 dB, surpassing the industrial requirement for commercial electronic protection. The enhanced performance is attributed to the PI veil acting as a dielectric interlayer that facilitates multiple internal reflections between the conductive titanium and carbon fiber phases, thereby shifting the primary shielding mechanism toward absorption. Skin depth analysis further substantiated that the neat veil optimizes the electromagnetic interaction within the hybrid structure. This research demonstrates that Ti/CF FMLs interleaved with neat PI veils provide a robust, dual-purpose solution for next-generation automotive engineering, ensuring structural integrity while shielding sensitive autonomous systems from electromagnetic disruption.