Design and performance of an electrically triggered 4D printed hinge: electro-thermo-mechanical behaviour of carbon black/polylactic acid

In the field of 4D printing, shape memory polymers are gaining more and more interest thanks to their large deformability and ease of manufacturing, compared to their metallic alloy counterparts. However, they are still rarely adopted for industrial applications, often limited by the poor time and space accuracy of their recovery behaviour. In this paper, the aim is to use an electroconductive shape memory polymer to design a hinge for the self-deployment of space structures. Fused filament fabrication and composite material made of polylactic acid filled with carbon black particles are used. First, the hinge is conceived as the answer to an inverse design problem: its geometry integrates an electrical circuit, and the influence of the printing parameters on the material’s properties for accurate Joule-heating is considered to perform the shape memory behaviour. Then, the deployment of the hinge is filmed and tracked thanks to a multi-instrumented setup to calculate its recovery ratio and kinetics and evaluate its performance. One to ten deployments are considered to study its behaviour under repeated use. Furthermore, the force deployed is measured and compared between the first and the tenth cycles to evaluate its durability. Results show that the hinge is able to recover up to 80% of its initial shape and deploy the same force through the cycles.