Screen Printed Circuits for Fiber-Reinforced Polymer Pultrusion

Abstract

There is very little literature on multifunctional composites, also known as "smart composites," made with printed electronics and pultrusion. Therefore, the primary goal of this thesis was to demonstrate the viability of combining two well-established, fully automated, high-volume manufacturing methods, rotary screen printed circuits and fiber-reinforced polymer pultrusion. Printed electronics benefit the composite structural health monitoring field by reducing weight, cost, complexity, and risk of delamination. A flatbed screen printer was used to substitute rotary screen printing. Printed electronics is a multidisciplinary field that involves structural, chemical, electrical, and material science knowledge.

Different inks were tested on substrates to find the optimal line width, pattern orientation, and pattern thickness to reliably produce unbroken circuits. That data was then used to design circuits and order a custom screen for printing the circuits on substrates. After printing, the circuits were verified to work and integrated into the pultrusion process. Finally, a small batch of circuits was integrated using a compression mold. The circuits printed with Inkron IPC-605x silver ink on laminate paper, and the Inkron IPC-605x and IPC-631 circuits printed on glass fiber produced functioning circuits. Unfortunately, other substrates and inks suffered from delamination and erosion during manufacturing.

In conclusion, the findings support continuing research combining rotary screen printed circuits with fiber-reinforced polymer pultrusion for structural health monitoring. In addition, future research should include ink analysis and test prints with rotary screen printing. Structural health monitoring is a critical component of composites due to high maintenance costs, the cost of non-destructive inspection, and the unreliability of visual surface inspections. Future applications for the circuits could involve strain monitoring and heating. Screen-printed circuits are lightweight, low-cost, and thin and are an excellent addition to traditional structural health monitoring technologies. This research provides a basis for continued work on screen-printed electronics for FRP pultrusion.