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  • AME Seminar

    Wed, Nov 17, 2021 @ 03:30 PM - 04:30 PM

    Aerospace and Mechanical Engineering

    Conferences, Lectures, & Seminars


    Speaker: Paul Kruger, Professor and Chair, Department of Mechanical Engineering, SMU

    Talk Title: Additives in Extrusion-Based Additive Manufacturing

    Abstract: Material additives in additive manufacturing (AM) can serve a variety of functions from improving the manufacturing process to adjusting material properties in the final build. This talk will discuss several uses of additives in extrusion-based additive manufacturing. The first focuses on using carbon-black-based additives in AM for silicones. Silicones have a range of desirable properties (durability, large elongation, bio-compatibility, etc.) that make them appealing for AM, but because they are thermosets, additional complexity is required to use them in AM, including in-situ curing of the material. In this work, carbon-black additives are shown to improve the print quality of silicone parts with UV-curing due to reducing disturbance of material deposition from electro-static forces, even though the concentration is too low to promote material conductivity. Carbon black is also shown to be an effective radiation absorbing agent, allowing for material heating via an infrared laser in printing of thermally-cured silicones.

    The second considers metallic micro-spheres as additives to promote electrical conductivity at sufficient concentrations to create printable electrically conductive polymer composites (ECPCs). ECPCs are useful for providing electrical connections, resistors, or other electrical functionality in printed parts. But for high conductivity, high concentrations of particles are required, making extrusion of the composite material difficult. Investigation of the rheology of these materials will be presented, using non-Newtonian silicones as a surrogate for the molten polymers during printing. The results show that the composite materials behave like power-law materials with a strong dependence on the particle concentration and the ratio of the diameter of the extrusion tube/nozzle to the mean particle diameter. For particle diameter decreasing toward 1, the flow consistency index (effective viscosity) decreases and then sharply increases as particles begin to jam within the tube. A semi-empirical model reproducing these effects will be presented.

    Stay after the seminar for a brief overview of graduate programs in Mechanical Engineering at SMU. Learn about research opportunities and unique degree programs including MS in Manufacturing Management and the direct admission PhD program.

    Biography: Paul Krueger received his B.S. in Mechanical Engineering in 1997 from the University of California at Berkeley. He received his M.S. in Aeronautics in 1998 and his Ph.D. in Aeronautics in 2001, both from the California Institute of Technology (Caltech). In 2002 he joined the Mechanical Engineering Department at Southern Methodist University (Dallas, TX) where he is currently a Professor and department chair. He is a recipient of the Rolf D. Buhler Memorial Award in Aeronautics, the Richard Bruce Chapman Memorial Award for distinguished research in Hydrodynamics, the Faculty Early Career Development (CAREER) Award from the National Science Foundation (2004), and the Ford Senior Research Fellowship from SMU (2012). His research interests include unsteady hydrodynamics and aerodynamics, vortex dynamics, bio-fluid mechanics, bio-morphic propulsion, fluid-boundary and fluid-particle interactions, and fluid processes in additive manufacturing.

    Host: AME Department

    More Info: https://usc.zoom.us/j/97427241653?pwd=UGd2aXY2b3dsQkxMdzdvcnNBMjRJZz09

    Webcast: https://usc.zoom.us/j/97427241653?pwd=UGd2aXY2b3dsQkxMdzdvcnNBMjRJZz09

    Location: Seaver Science Library (SSL) - 202

    WebCast Link: https://usc.zoom.us/j/97427241653?pwd=UGd2aXY2b3dsQkxMdzdvcnNBMjRJZz09

    Audiences: Everyone Is Invited

    Contact: Tessa Yao

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