Browsing by Subject "layer-by-layer"

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    Effect of In-Situ Compaction and UV-Curing on the Performance of Glass Fiber-Reinforced Polymer Composite Cured Layer by Layer
    (University of Texas at Austin, 2018) Beyene, Shiferaw D.; Ayalew, Beshah; Pilla, Srikanth
    In this paper, the effect of in-situ compaction and UV-induced curing on the performance of fiber-reinforced diglycidyl ether bisphenol A (DGEBA) based epoxy is studied for a layer-by-layer curing process. The optimum percentage of photo-initiator concentration and UV-intensity were obtained by conducting a different experiment for each of them. Fourier Transform Infrared (FTIR) spectroscopy method is used to determine the degree of cure. Then, short beam shear (SBS) test is conducted to measure the inter-laminar shear strength of the cured product under different compaction load. The UV intensity and Photo-initiator concentration were kept constant during the test. The result showed that thick composite parts fabricated with in-situ compaction and UV curing process have showed increased inter-laminar shear strength with increased compaction load up to a certain point. An increase in compaction beyond this point decreased the interlaminar-shear strength.
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    In-Situ Thermal Image Correlation with Mechanical Properties of Nylon-12 in SLS
    (University of Texas at Austin, 2015) Wroe, Walker; Gladstone, Jessica; Phillips, Timothy; McElroy, Austin; Fish, Scott; Beaman, Joseph
    Selective laser sintering (SLS) of Nylon is a significant portion of the additive manufacturing market for structurally sensitive applications. Current methods of acceptance for such parts are based on the inclusion of ASTM tensile test specimens within the build volume to assess the overall build quality. Ultimate strength and elongation of these specimens oriented both in-plane and normal to the layer build direction are the primary quality metrics. This paper looks at a more complete method of certifying parts for acceptance based on examination of the build conditions in each layer of the part by comparing layer-by-layer thermal conditions during the part build to the resulting ASTM specimen tensile properties. Through such a comparison, a more complete three-dimensional assessment of part quality during the build process can be constructed. The layer-by-layer assessment used here is derived from infrared thermal imaging; mapping temperature profiles of SLS-built tensile bars with data collected before, during, and after each layer-wise laser melting sequence. Mechanical properties and fracture conditions are then quantified and correlated with the conditions where the fractures occur. Build conditions associated with poor failure conditions may then be used to assess poor SLS bonding throughout the part volume, improving overall part quality assessment and certification. As the method is matured, real time layer-by-layer assessment will be linked to SLS control, to correct for observed defects during the build and improve overall part quality and repeatability.