DEVELOPMENT OF ADVANCED MULTI-NOZZLE MULTI-MATERIAL 3D PRINTING

Abstract

Extrusion-based 3D printing methods, such as Direct Ink Writing, are extensively utilized across sectors like biomedical, energy, and electronics, employing a diverse range of materials. However, the lengthy printing times associated with single-nozzle systems limit their application in complex mass production and rapid prototyping. While multi-nozzle systems have attempted to address this issue, they often result in costly, and bulky setups with limited material options. This research introduces a novel multi-nozzle multi-material system that allows for simultaneous 3D printing using bent nozzles. The system is cost-effective, simple in design, and capable of printing a wide range of materials. Its universal design enables its integration with the commercially available printers and can reduce printing time by up to 90%. The capabilities of the multi-material setup are demonstrated through the 3D printing of soft, variable-stiffness elastomers for biomimetic robotic applications. Due to the rapid curing of elastomers in additive manufacturing, the change in mechanical properties of the 3D printed material were experimentally characterized. 3D printed ecoflex 00-10, Dragon skin 20, and a combination of both in layered format were evaluated. We then determined material parameters for incompressible hyperelastic strain energy function using the Mooney-Rivlin model (2nd, 3rd, and 5th order) and the Yeoh model (2nd and 3rd order). The Mooney-Rivlin model showed better alignment with experimental data, and these parameters were used to validate the results in ANSYS simulations. A fully 3D printed 100% elastomeric biomimetic octopus arm with gradient stiffness was successfully fabricated. A comparative study was conducted between the 100% elastomeric arm and an identical arm design integrated with metallic spring steel for controlled stiffness gradient. The elastomeric arm demonstrated controlled bending similar to the non-elastomeric version, validating the potential for 3D printing functionally gradient stiffness elastomers for robotic applications. Additionally, the developed model was used to predict the arm’s deformation through actuation via ANSYS simulation, which also aligned well with experimental results. Furthermore, this dissertation investigates the impact of printing parameters on oozing, a common problem affecting print quality in direct ink writing. The newly developed system, along with the parameter characterization, and oozing study, makes the multi-nozzle systems more affordable and capable of printing advanced material combinations with improved print quality. This breakthrough in additive manufacturing opens new avenues for fabricating entirely soft robotic structures with controlled variable stiffness configurations, offering better deformation control and improved functionality in high pressure environment, where the integration of rigid components presents significant challenges.