Electromagnetic interference shielding of stitched carbon fiber composites

This study reports on the improvements in the electromagnetic interference shielding effectiveness of unidirectional carbon fiber-epoxy composites as a results of stitching with conductive and nonconductive threads. Unidirectional carbon fiber laminates stitched with copper, titanium, Kevlar metallic, Kevlar 10 and Dyneema T90 threads were manufactured using vacuum assisted resin infusion process. Representative samples from each laminate were tested in directions normal and axial to the fiber direction using rectangular waveguide. Experimental results showed that composites with improved shielding effectiveness in both directions were produced. For example, stitching with copper doubled the shielding effectiveness in the axial direction when compared to the unstitched laminate. In addition, composite stitched with Dyneema exhibited the most balanced increase in the shielding effectiveness in both axial and normal directions (91.5% and 17.3%, respectively) compared to the unstitched laminate. The shielding mechanism of the composites was mainly reflection.