Development of functionally graded properties components via filament foaming in material extrusion

Abstract Additive technologies enable designers to conceptualize and produce components with local properties by manipulating their shape and material properties. In this sense, it is possible to create parts that exhibit heterogeneous or gradual properties variations in the volume. Among the numerous options to modify component properties, one can operate on the material itself. This is achieved by using materials that can change their final properties through the variation of process parameters. In fused filament fabrication, one strategy is to adopt a foaming agent with activation temperature suitable for the melting temperature of the material. In this work a design method for functionally graded properties components is developed for fused filament fabrication of materials with temperature activated foaming behavior. Two PLA materials are characterized with respect to their density, Shore D hardness, elastic modulus, ultimate tensile strength, elongation at break. Mathematical models for the characterized properties are subsequently derived to support the design phase. The design approach is based on a G-Code post processing routine which modifies the extrusion temperature and the material flow rate parameters. Finally, examples of components based on the proposed design method are provided. Graphical Abstract