Abstract
Despite the considerable progress in additive manufacturing technologies, most 3D printers that are low cost and accessible remain merely as tools for rapid prototyping of 3D structural objects due to the lack of manufacturable functional structures. This thesis explores the parametric manipulation of fused filament fabrication (FFF/FDM) printers to fabricate non-uniform structures with functional elements. This study explored two distinct approaches: 4D printing and fabrication of pores via parametric design. Chapter 2 discussed the parametric design of FDM-based 4D printing. Exploiting the transient properties of stimuli-responsive materials, the inception of 4D printing has introduced the concept of programmable self-morphing structures. While many approaches investigate an array of programmable materials and their interactions with various stimuli, the digital manipulation of multiple process parameters to trigger a range of controllable actuation deserves more attention. Through the investigation of FDM parameters on the thermo mechanical deposition properties of polyurethane, the heat-sensitive shape memory polymer has been programmed with various inelastic strains to achieve a range of bending curvatures with a bilayer shrinkage mechanism. Chapter 3 discusses the fabrication of arbitrary pores within FDM-printed 3D models. Multi-material 3D printing has also witnessed growing demand due to the heterogeneous distribution of dissimilar material properties within a structure. However, it introduces an array of problems such as the compromised interfacial bonding strength between disparate materials. Algorithmic approaches have been developed to design functionally graded structures with a single material by modulating material composition throughout the structure for desired functions. However, they are generally hard to control and non-intuitive for users. Herein, a user-centric parametric framework, 4oreDimension, was designed to introduce variable micropores to FDM-printed structures without alterations to the extrusion toolpath. 4oreDimension allows the creation of (1) moving parts, (2) bending parts, and (3) fracture points using a single material with commercially available and low-cost FDM 3D printers, offering an opportunity to custom-design functional materials by 3D printing. Equipped with versatile functional structures that can be printed with a single material, this thesis aims to diversify the toolkit for consumer FDM printing. Unlike the intricately agglomerated multi-material products, this single material approach also serves as impetus towards circular economy in the manufacturing industry.