Lightweight Conductive Paths for Structural Health Monitoring Systems Using 3d-printed Metallic and Carbon-filler Based Inks.
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Guided wave-based structural health monitoring (SHM) systems using piezoelectric sensors for composite parts face challenges due to the weight of copper wiring. This study developed lightweight, 3D-printed conductive paths using silver ink (Dycotec Materials) and epoxy (Epolam 8052) doped with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). The inks were characterized for viscosity using rheological techniques, nanoparticle dispersion via optical and scanning electron microscopy, and circuit conductivity with a Keithley 2410. The printed circuits were evaluated for signal transmission of guided waves, easy integration with induction heating and were subjected to fatigue testing. Nanoparticle-doped epoxy inks demonstrated increased viscosity and controlled circuit dimensions, though dispersion issues led to voids and agglomerates. Unmodified silver inks did not show good printing quality; however, the quality was improved significantly with the adding of GNPs. Circuits from both inks were evaluated for conductivity and signal transmission. Silver inks achieved conductivity levels comparable to copper and effective signal transmission, while nanoparticle-doped epoxy had significantly lower conductivity and signal loss (2-3 times), even at its best formulation. Fatigue tests revealed excellent durability for both metallic and nanoparticle-doped epoxy circuits. A lightweight film integrating silver circuits was successfully bonded to a composite panel using induction heating, demonstrating a rapid integration method for SHM systems. These findings highlight the potential of metallic and nanoparticle-doped inks to replace traditional copper wiring, offering significant weight reduction, and easier integration capabilities for SHM applications.
