Metal additive manufacturing allows for the rapid production of complex parts that are otherwise impractical using conventional subtractive manufacturing techniques. Applications for additive manufacturing span across a broad array of industries including aerospace, automotive, and medical, among many others. One metric of printing success is material properties, including part density. While there has been extensive research completed for the density of printed parts, there is little published work concerning powder packing density on the build plate associated with powder spreading.
In this thesis, a Discrete Element Method (DEM) model was created in Abaqus to simulate the spreading behavior of particles through a single sweep of a spreader blade . Spreading behavior was investigated for three different build plate configurations: a flat build plate, a build plate with a small protruding feature, and a build plate with the same protruding feature split into quarters. For each configuration, the 2D packing behavior of the particles were analyzed during the powder spreading process. Different packing patterns seen in the 2D packing behavior were further analyzed to determine particle packing density, analogous to unit cell packing, and to predict 3D packing behavior and packing density. Additionally, particle packing density was measured following simulation using 2D image analysis to quantify powder spreading around, and interaction with, previously fused structures on the build plate. We found that the local packing fraction is measurably disrupted when particles interact with build plate features, providing insights into part density and short loading during part fabrication.
| Identifer | oai:union.ndltd.org:CALPOLY/oai:digitalcommons.calpoly.edu:theses-3645 |
| Date | 01 June 2020 |
| Creators | Ng, Priscilla |
| Publisher | DigitalCommons@CalPoly |
| Source Sets | California Polytechnic State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Master's Theses |
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