Browsing by Subject "Nylon-12"
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Item 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, JosephSelective 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.Item Process and Properties of Carbon Black-Filled Electrically Conductive Nylon-12 Nanocomposites Produced by Selective Laser Sintering(University of Texas at Austin, 2009-09) Artreya, S.; Kalaitzidou, K.; Das, S.Electrically conductive polymer composites are suitable for use in the manufacture of antistatic products and components for electronic interconnects fuel cells and electromagnetic shielding. Selective laser sintering (SLS) was used to investigate the fabrication of electrically conductive nanocomposites of Nylon-12 filled with 4% by weight of carbon black. The effect of laser power and the scan speed on the flexural modulus and part density of the nanocomposite were studied. The set of parameters that yielded the maximum flexural modulus and part density was used to fabricate specimens to study the tensile, impact, rheological and viscoelastic properties. The electrical conductivity of the nanocomposite was investigated. The densities and the microstructures of the nanocomposites were studied using optical microscopy and scanning electron microscopy (SEM). The morphology of the nanocomposites was investigated using X-Ray diffraction (XRD) and differential scanning calorimetry.Item SLS Nylon 12 Characterization Through Tensile Testing and Digital Image Correlation for Finite Element Modeling of Food and Ankle-Foot Orthoses(University of Texas at Austin, 2010) Muraru, L.; Pallari, J.; Creylman, V.; Vander Sloten, J.; Peeraer, L.Selective Laser Sintering has been recently proposed as a feasible engineering technique for manufacturing of customized ankle-foot orthoses (AFOs). Development of computer-aided design (CAD) models and virtual evaluation of the orthotic devices are important steps in the engineering design process. This paper will describe a method for accurate characterization of SLS Nylon 12 mechanical properties to be implemented in the finite element models (FEM) of AFOs. Elastic mechanical properties were determined for principal and perpendicular building directions.Item Sustainability and thermal aspects of polymer based laser sintering(2010-12) Sreenivasan, Rameshwar; Bourell, David Lee; Beaman Jr., Joseph J.Additive Manufacturing (AM) processes which include Selective Laser Sintering (SLS) have experienced tremendous growth and development since their introduction over 20 years ago. It becomes highly important at this stage to evaluate the sustainability of the process and refine it to reduce energy and material consumption. In this study, a sustainability analysis was performed on the SLS process with Nylon-12 using the Environmental and Resource Management Data (ERMD) known as Eco-Indicators. The energy perspective alone was considered and a Total Energy Indicator (TEI) value was calculated using various parameters to quantify process sustainability: process productivity, energy consumption rate, etc. Precise thermal control of selective laser sintering (SLS) is desirable for improving geometric accuracy, mechanical properties, and surface finish of parts produced. An experimental setup to monitor the temperature distribution was designed using Resistance Temperature Detectors (RTD) as a part of this study. Discrepancies in temperature profiles were investigated and recommendations were made to improve thermal characteristics of the SLS process.