Design and Testing of Multi-Material Shape-Changing Flexure Hinges for Fused Filament Fabrication

Living hinges are non-assemblable flexible joints that allow the relative rotation of two adjacent rigid parts through bending. Conventionally, living hinges are single-material designs made through injection moulding, for example. In order to reduce mould complexity, flexure hinges have a restrictive design. However, 3D printing technologies, such as Fused Filament Fabrication - FFF, can provide new opportunities for hinge development, allowing more design freedom and a wide range of materials. This paper focused on exploring and testing various multi-material hinges designs with bidirectional folding made of compatible and low-compatible thermoplastic materials. The resulting designs have corrugated structures and shape-changing interfaces, each with multiple solutions. They were printed as samples made of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) for the rigid bodies and with thermoplastic co-polyesters (TPC) for the hinge. The results show that corrugated and shapechanging structures can be used as a design solution for flexure hinges.