Morphing satellite dishes: 3D-printed fiber composites shape themselves in space

Transporting large structures such as satellite dishes into space is expensive and logistically demanding. A research team at the University of Illinois Urbana-Champaign is now demonstrating how flat, 3D-printed composite materials can be transformed into complex 3D geometries in orbit using very little energy. Aerospace engineering PhD student Ivan Wu and his advisor Jeff Baur combine continuous fiber 3D printing with an energy-efficient resin chemistry and use frontal polymerization as the curing mechanism.

At the heart of the approach is a continuous carbon fiber 3D printer that deposits fiber bundles, each about the thickness of a human hair, in a defined pattern onto a build platform. As the bundles are laid down, they are compressed and partially cured with UV light so that a programmable fiber layout is created. [ZITAT1]“We used the continuous carbon fiber 3D printer to print bundles of fiber, with each fiber about the diameter of a human hair,” Wu said. “As the fiber bundles are drawn by the printer onto a bed, they are compressed and exposed to ultraviolet light, which partially cures them.”[/ZITAT1] The resulting fiber preform is then infiltrated with a specially formulated liquid resin, frozen, and only activated in space by a small heat input. The propagating reaction front cures the part through its thickness, eliminating the need for large ovens or autoclaves.

One key challenge lay in the so-called inverse problem: starting from a target geometry, the corresponding 2D fiber pattern has to be computed. Wu developed equations and code that allow the printer to generate fiber layouts for different target shapes – including cones, saddle surfaces and parabolic antennas. He drew inspiration from the paper art of kirigami, in which cuts are combined with folds to achieve complex curvatures.

From a mechanical standpoint, morphing structures require a compromise between deformability and stiffness. For large shape changes, a low fiber volume fraction is selected, which keeps the structure flexible but not yet stiff enough for direct use as a spaceflight component. The team therefore proposes first using the activated 3D forms as reusable molds and then building highly stiff laminate structures on top of them in space, once again cured via frontal polymerization. In this way, large reflectors or support structures could be launched in a flat-packed configuration and only brought into their final shape in orbit – a concept that could in the future also be applied to hard-to-reach regions on Earth.