Mechanical property variation in metal lattice struts
| dc.contributor.advisor | Seepersad, Carolyn | |
| dc.creator | Dressler, Amber Dawn | |
| dc.creator.orcid | 0000-0003-0463-1216 | |
| dc.date.accessioned | 2018-10-19T23:14:59Z | |
| dc.date.available | 2018-10-19T23:14:59Z | |
| dc.date.created | 2018-05 | |
| dc.date.issued | 2018-05 | |
| dc.date.submitted | May 2018 | |
| dc.date.updated | 2018-10-19T23:14:59Z | |
| dc.description.abstract | Direct metal laser sintered lattice structures offer favorable tradeoffs between strength and weight, which are of interest to designers. However, manufacturing defects present throughout the lattices create significant variability in mechanical properties and part performance. The goal of this research is to improve the understanding of how defects impact mechanical properties to enhance designers’ ability to design metal lattice structures reliably. Before analyzing full lattices, it is important to understand how design parameters impact individual lattice struts during manufacturing. To test individual lattice struts, tensile specimens with five struts interrupting the gauge section were manufactured in three strut diameters and two build orientations. Testing different strut diameters investigates how defects change with feature size when all features are less than 1 mm in diameter. The two build orientations orient struts parallel to the build platform (horizontal) and perpendicular to the build platform (vertical). The horizontal struts represent the worst-case scenario since the struts are completely unsupported, which often leads to excessively weak, rough, or nonexistent structures in DMLS. In an actual lattice, there would be a range of orientations from horizontal to vertical depending on the lattice orientation. In addition to the strut samples, solid tensile samples were manufactured to evaluate the bulk material properties and associated variability at a larger size scale, less impacted by small defects. Before tensile testing the samples, non-destructive analysis was conducted on each sample, including methods include visual inspections, geometric measurements, density measurements, and computed tomography scans. Then, each sample was tension tested and imaged throughout testing. Following testing, the fracture surfaces and testing data were analyzed to investigate failure trends in search of a robust design. The CT scan data showed that the cross-sectional area of the struts was smaller than desired and that the horizontal struts were rougher than the vertical struts. Due to the poor quality of horizontal struts, the strut samples exhibited more variation in ultimate strength than the solid samples. Since five independent cracks are required to completely fracture a strut sample, the strut samples had less variation in percent elongation than the solid samples. | |
| dc.description.department | Mechanical Engineering | |
| dc.format.mimetype | application/pdf | |
| dc.identifier | doi:10.15781/T27S7JB8S | |
| dc.identifier.uri | http://hdl.handle.net/2152/69095 | |
| dc.language.iso | en | |
| dc.subject | Additive manufacturing | |
| dc.subject | Direct metal laser sintering | |
| dc.subject | Lattice | |
| dc.title | Mechanical property variation in metal lattice struts | |
| dc.type | Thesis | |
| dc.type.material | text | |
| thesis.degree.department | Mechanical Engineering | |
| thesis.degree.discipline | Mechanical Engineering | |
| thesis.degree.grantor | The University of Texas at Austin | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science in Engineering |
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