Impact of Infill and Shell Design Features on Compression Stiffness in Material Extrusion of Thermoplastic Urethane
Data sets for Impact of Infill and Shell Design Features on Compression Stiffness in Material Extrusion of Thermoplastic Urethane as submitted to Materials & Design.
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The parts used in this study were fabricated using a LulzBot TAZ 6 printer, an open-source desktop 3D-printer manufactured by Aleph Objects, Inc. The slicing software used to generate the G code for each part was Cura LulzBot Edition. The following settings were consistent for all parts manufactured: 225°C extrude temperature, bed temperature (55°C for NinjaFlex® and 30°C for PolyFlex®), 0.2mm slice height, and 175mm/s travel speed. For each experiment, the print settings for number of shells, infill pattern, and infill percentage were adjusted in the Cura software as described in the factorial design of experiments. Experimental testing was conducted to determine the compressive performance of all the fabricated parts using a procedure derived from the ASTM testing standard D575 – 91 Rubber Properties in Compression. The standard was adapted to better investigate the impact of infills by increasing the thickness of the test pieces from 12.5 mm to 25.4 mm for a larger ratio of infill to solid top and bottom layers. It was also adapted to square test pieces in place of cylinders to enable investigation of the impact of corners on part stiffness. The dimensions of each test piece were obtained through caliper measurements and recorded. The parts were then compression tested on an MTS Criterion C43.304 machine to obtain stress vs. displacement measurements. Compression testing of each part configuration was along the vertical Z build axis. The experimental set up for testing can be seen in Fig. 1. Parallel platens were used in the MTS machine to compress the sample parts at room temperature of 21° C. The MTS machine was used with 1kN and 3kN load cells. Key settings on the MTS machine included: Deflection rate of 12.65 mm/min, data acquisition rate of 10 Hz for stress & strain data, and a peak deflection point of 20%.