Photo-Curing 3D Printing of Thermosetting Sacrificial Tooling for Fabricating Fiber-Reinforced Hollow Composites

Carbon fiber-reinforced hollow composites play a vital role in lightweighting modern cars and aircrafts. Fabrication of such hollow composites with seamless internal finish requires sacrificial tooling that can be used under pressure and high temperature. For the very first time, high performance sacrificial tooling that can be used to fabricate fiber-reinforced hollow composites is produced using photocuring 3D printing technology. This is achieved by developing UV-curable resins containing highly soluble yet hydrolysable acetal acrylate cross-linker and hydrophilic 4-acryloylmorpholine monomer. It is found that the cross-linker content greatly affects the printing speed. Further, the widely adopted UV post-curing method is found to have negligible impact on improving the thermal-mechanical properties of printed structures. After thermal post-treatment, printed sacrificial tooling exhibits a heat deflection temperature of 112 degrees C at 0.455 MPa and an average coefficient of linear thermal expansion of 59 ppm degrees C-1 between 30 and 100 degrees C. As a result, printed tooling enables fabrication of carbon fiber-reinforced hollow composites with complex geometry, which shows a tensile strength of 802 MPa and an elastic modulus of 50.2 GPa.

Automated summary

High performance sacrificial tooling for fabricating fiber-reinforced hollow composites is successfully developed using photocuring 3D printing technology. UV-curable resins containing soluble and hydrolysable acetal acrylate cross-linker and hydrophilic 4-acryloylmorpholine monomer are used to achieve seamless internal finish. The content of cross-linker has a significant impact on printing speed, while the widely adopted UV post-curing method has negligible effect on improving thermal-mechanical properties. Printed sacrificial tooling, after thermal post-treatment, exhibits excellent thermal stability and enables fabrication of carbon fiber-reinforced hollow composites with complex geometry, showing high tensile strength and elastic modulus.