Thermomechanical and Powder Sintering Aspects in Electron Beam Additive Manufacturing - Applications to Overhang Support Designs

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The goal of this research is to renovate the support structure designs for part overhang geometries in powder-bed Electron Beam Additive Manufacturing (EBAM). It is hypothesized that the poor thermal conductivity of sintered powders is the root cause of part defects such as warping associated with part overhang (or similar) geometries. Hence, the required function of support structures is not from the weight-carrying standpoint; rather, the complex thermal and mechanical phenomena of the EBAM process, which lead to residual stresses and distortions, should be studied for functional support designs. Specifically, this research will characterize sintered powder porosity and its effects on thermal properties, develop finite element thermomechanical simulations incorporating porosity-dependent thermal properties for temperature and stress predictions in EBAM, evaluate overhang geometry effects on the part thermomechanical behaviors in EBAM and correlate with warping severity, and investigate different support patterns to evaluate the effectiveness of a designed support.The outcome of this research will enhance the performance and efficient usage of the EBAM technology through improved and effective support structures. Thus, the project will directly benefit the users of metal Additive Manufacturing (AM) technologies, strengthening the global competitiveness of the nation's industry. Collaborating with one of primary EBAM users, Marshall Space Flight Center, the research team may further apply findings to tackle pragmatic problems that exist in AM technologies. Moreover, new process understanding from this research will benefit studies on other powder-based AM processes such as selective laser sintering. In addition, working with the National Center for Manufacturing Sciences, the research team will disseminate the project results timely and widely to the AM industry. Further societal impacts of this research include reviving high school students' interest in engineering and technology, particularly, from underrepresented groups.