Recent studies have shown that post-manufacture iso-thermal annealing of structures fabricated via FFF may increase the inter-laminar toughness of these parts by over an order of magnitude through reptation of polymer chains at the inter-layer. In these studies, however, the structure was confined to a fixture during annealing to limit deformation via creep and release of residual thermal stresses. In this work, we report on a novel method for fabricating structures via FFF using a dual material filament to create structures with a dual material composition of macro-structurally distinguishable thermomechanical properties. When the structure is annealed, one material phase is used to increase reptation and healing of the inter-laminar interface, while the other material phase remains geometrically stable during the process, limiting deformation of the structure as a whole. Critical elastic-plastic strain energy release rates of annealed, dual material specimens were evaluated using the single edge notch bend sample geometry and show marked improvements over homogeneous samples fabricated from either of the individual constituents. Additionally, geometric stability of dual material samples was evaluated using a sag test and show minimal deformation during the high temperature annealing process, now allowing free-standing post-process annealing.
- Manufacture multi-material filament for applications in fused filament fabrication.
- Evaluate the fracture performance of additively manufactured materials