Achieving Functionally Graded Material Composition Through Bicontinuous Mesostructural Geometry in Material Extrusion Additive Manufacturing

• Published in: JOM (1989) 2018-03, Vol.70 (3), p.413-418
• Main Authors: Stoner, Brant, Bartolai, Joseph, Kaweesa, Dorcas V., Meisel, Nicholas A., Simpson, Timothy W.
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Boolean; Chemistry/Food Science; Concentration (composition); Design; Earth Sciences; Engineering; Environment; Extrusion; Functionally gradient materials; Geometry; Inequality; Physics; Solid Freeform Fabrication; Surface structure
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-017-2669-z

Functionally graded materials (FGMs) gradually change composition throughout their volume, allowing for areas of a part to be optimized for specific performance requirements. While additive manufacturing (AM) process types such as material jetting and directed energy deposition are capable of creating FGMs, design guidelines for varying the material composition in an FGM do not exist. This article presents a novel design solution for FGMs: creating the material gradient by varying the mesostructural size and thickness of bicontinuous, multi-material geometries. By using a bicontinuous structure, such as Schoen’s gyroid surface or Schwarz’s P and D surfaces, each component material exists as a continuous discrete structure, which allows FGMs to be fabricated by a wider range of AM processes. The gradient is created by varying the volume fraction occupied by the surface structure inside the part volume. This article explores the use of this technique to create FGMs with material extrusion AM. Properties of these bicontinuous structures are experimentally characterized and shown to outperform typical material extrusion FGMs.