Fiber-reinforced polymer composites (FRPCs) have been widely adopted in various industries from aerospace to automotive to energy sectors, owing to their combination of superior thermal and mechanical properties and high stability at elevated temperatures. FRPCs are conventionally manufactured using expensive molds or tooling to shape the resin and fibers. Design and manufacturing of molds is a labor-intensive and quite expensive process which imparts a significant economic barrier for creation of complicated molds or changing the design of composite products. In marked contrast, additive manufacturing (AM) allows us to readily fabricate composite parts with minimal tooling at lower cost and higher design flexibility. However, AM of FRPCs using traditional thermoset composite materials and underlying curing strategies is quite challenging, as long and energy- intensive cure cycles are often required to transform the matrix resin of composites to a solid polymer, which cannot be implemented during rapid printing processes. Recently, several approaches have been developed for AM of FRPCs using thermoplastic matrix polymers via fused filament fabrication (FFF) or in-situ curing of uv-curable thermoset resins. However, the printed polymers are typically not suitable for structural applications, due to the limited volume fractions of continuous fiber reinforcements, large void contents, and use of polymers with poor thermal stability and mechanical properties. Here, we present a novel technique for AM of continuous FRPCs using a high-performance thermally curable resin that cures instantaneously during the curing process, allowing for capturing the desired print geometry. Using this technique, we demonstrate AM of FRPCs at high rates on a print bed (i.e., supported printing) and off the tool plate (i.e., freeform printing in mid-air).
Learning Objectives:
- Discuss the challenges with current techniques for additive manufacturing of fiber-reinforced polymer composites
- Describe a new technique for additive manufacture of composites using thermally curable resins
