Holzman, Noah2020-01-102020-01-102019-11https://hdl.handle.net/11299/211309University of Minnesota M.S.Mat.S.E. thesis. November 2019. Major: Material Science and Engineering. Advisor: Lorraine Francis. 1 computer file (PDF); v, 45 pages.3D printing of soft, elastomeric materials has potential to increase the accessibility while decreasing the cost of customizable soft robotics and biomedical devices. In this work, the steps to building a 3D printer capable of printing with an extrudable liquid are described. A moisture-cure room temperature vulcanizing (RTV) silicone elastomer was 3D printed. The relative density of printed specimens was determined as a function of infill density specified in the software and the relationship was found to be non-linear and dependent on the sample geometry. Printed test specimens with a range of infill densities and several infill geometries were characterized under uniaxial tension and compression. In tension, the stress-strain behavior is non-linear over the entire curve. Ultimate tensile strength was relatively unaffected by infill density over a range of relative densities from 0.35 to 1.0, while extension at break decreased with increasing infill density. The apparent Young’s modulus was determined in the small-strain limit and is tunable from 310-1150 kPa by adjusting the infill density. Tensile strength of fully-dense printed samples (1150±30 kPa) is comparable to that of the bulk cast samples (1150±40 kPa), indicating good performance of the printing process and few defects. In compression, three different infill patterns and a range of infill patterns were tested. The specimens exhibit stress-strain behavior typical of foams—a linear elastic region with a modulus dependent on infill density, followed by a buckling plateau region and densification at high strains. Negative stiffness due to snap-through buckling was observed in some cases. Results for both tension and compression tests show the tunability of mechanical response achievable through changing the software infill density.en3D PrintingElastomersSiliconeThesis or Dissertation