{"id":{"repo_id":"alabama","oai_identifier":"oai:ir.ua.edu:123456789/3136"},"canonical_url":"https://search.dev.ndltd.org/etd/alabama/oai:ir.ua.edu:123456789/3136","repository":{"repo_id":"alabama","name":"University of Alabama","base_url":"https://ir-api.ua.edu/oai/request"},"display":{"title":"Thermal and thermomechanical studies of beam-based powder-bed additive manufacturing processes","abstract":"Powder-bed beam-based metal additive manufacturing (AM) such as electron beam additive manufacturing (EBAM) and selective laser melting (SLM) has a potential to offer innovative solutions to many challenges faced in the manufacturing industry. However, due to complex heat transport and thermomechanical interactions, the physical process of powder-bed AM has not been fully understood. This dissertation research focuses on the process thermal analysis, thermomechanical modeling and deformation studies of powder-bed metal AM parts. The primary objectives of this research are: (1) to develop a 3D finite element (FE) thermal model to study the powder porosity effect in EBAM, validated by near infrared thermography; (2) to apply the developed thermal model and study, supported by experiments, the thermal response under different process parameters; (3) to simulate the SLM process using the developed 3D thermal model; (4) to develop a 3D thermomechanical FE model to study temperature, stress and deformation characteristics in EBAM overhang parts for different powder sintering conditions; (5) to investigate different support structures for overhang deformation in EBAM; (6) to investigate an overhang support design method for structure optimization. The major findings are summarized as follows. (1) For beam process parameters of 632 mm/s speed, 6.7 mA current and 0.55 mm diameter, the peak temperature is ~2700 °C and melt pool size is 2.94 × 1.09 × 0.12 mm (length, width and depth). (2) Process parameters affect thermal characteristics. For 482 vs. 1595 mm/s speed, given 7.7 mA current and 0.65 mm diameter, the peak temperatures are 2572 vs. 2326 °C and the melt pool lengths are 2.35 vs. 1.25 mm. (3) In SLM, the residual heat can increase the melt pool size from raster scanning; e.g., the melt pool depth changes from ~0.085 mm to ~0.11 mm at given parameters. (4) In thermomechanical simulations, the results revealed that decreasing the powder-bed porosity (50% vs. 35%) can reduce the process temperatures, part residual stresses and overhang deformations. (5) A contact-free heat support beneath an overhang may effectively minimize overhang deformations. (6) The proposed support design methodology may eliminate part overhang deformations using less support materials.","abstract_html":"Powder-bed beam-based metal additive manufacturing (AM) such as electron beam additive manufacturing (EBAM) and selective laser melting (SLM) has a potential to offer innovative solutions to many challenges faced in the manufacturing industry. However, due to complex heat transport and thermomechanical interactions, the physical process of powder-bed AM has not been fully understood. This dissertation research focuses on the process thermal analysis, thermomechanical modeling and deformation studies of powder-bed metal AM parts. The primary objectives of this research are: (1) to develop a 3D finite element (FE) thermal model to study the powder porosity effect in EBAM, validated by near infrared thermography; (2) to apply the developed thermal model and study, supported by experiments, the thermal response under different process parameters; (3) to simulate the SLM process using the developed 3D thermal model; (4) to develop a 3D thermomechanical FE model to study temperature, stress and deformation characteristics in EBAM overhang parts for different powder sintering conditions; (5) to investigate different support structures for overhang deformation in EBAM; (6) to investigate an overhang support design method for structure optimization. The major findings are summarized as follows. (1) For beam process parameters of 632 mm/s speed, 6.7 mA current and 0.55 mm diameter, the peak temperature is ~2700 °C and melt pool size is 2.94 × 1.09 × 0.12 mm (length, width and depth). (2) Process parameters affect thermal characteristics. For 482 vs. 1595 mm/s speed, given 7.7 mA current and 0.65 mm diameter, the peak temperatures are 2572 vs. 2326 °C and the melt pool lengths are 2.35 vs. 1.25 mm. (3) In SLM, the residual heat can increase the melt pool size from raster scanning; e.g., the melt pool depth changes from ~0.085 mm to ~0.11 mm at given parameters. (4) In thermomechanical simulations, the results revealed that decreasing the powder-bed porosity (50% vs. 35%) can reduce the process temperatures, part residual stresses and overhang deformations. (5) A contact-free heat support beneath an overhang may effectively minimize overhang deformations. (6) The proposed support design methodology may eliminate part overhang deformations using less support materials.","abstract_has_math":false,"creators":["Cheng, Bo"],"institution":"University of Alabama Libraries","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Midkiff, K. Clark","Allison, Paul Galon","Barkey, Mark E.","Nastac, Laurentiu"],"advisors":["Chou, Y. Kevin"],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016","date_published":"2016","updated_at":"2026-07-27T18:44:20Z","subjects":["Mechanical engineering"],"languages":["en_US","English"],"rights":["All rights reserved by the author unless otherwise indicated."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["u0015_0000001_0002503","Cheng_alatus_0004D_12950"],"render_values":[{"text":"u0015_0000001_0002503","href":null,"code":true},{"text":"Cheng_alatus_0004D_12950","href":null,"code":true}]}]},"links":{"outbound_url":"http://ir.ua.edu/handle/123456789/3136","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Midkiff, K. Clark","Allison, Paul Galon","Barkey, Mark E.","Nastac, Laurentiu"]},{"key":"dc:contributor.advisor","label":"Advisor","values":["Chou, Y. 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However, due to complex heat transport and thermomechanical interactions, the physical process of powder-bed AM has not been fully understood. This dissertation research focuses on the process thermal analysis, thermomechanical modeling and deformation studies of powder-bed metal AM parts. The primary objectives of this research are: (1) to develop a 3D finite element (FE) thermal model to study the powder porosity effect in EBAM, validated by near infrared thermography; (2) to apply the developed thermal model and study, supported by experiments, the thermal response under different process parameters; (3) to simulate the SLM process using the developed 3D thermal model; (4) to develop a 3D thermomechanical FE model to study temperature, stress and deformation characteristics in EBAM overhang parts for different powder sintering conditions; (5) to investigate different support structures for overhang deformation in EBAM; (6) to investigate an overhang support design method for structure optimization. The major findings are summarized as follows. (1) For beam process parameters of 632 mm/s speed, 6.7 mA current and 0.55 mm diameter, the peak temperature is ~2700 °C and melt pool size is 2.94 × 1.09 × 0.12 mm (length, width and depth). (2) Process parameters affect thermal characteristics. For 482 vs. 1595 mm/s speed, given 7.7 mA current and 0.65 mm diameter, the peak temperatures are 2572 vs. 2326 °C and the melt pool lengths are 2.35 vs. 1.25 mm. (3) In SLM, the residual heat can increase the melt pool size from raster scanning; e.g., the melt pool depth changes from ~0.085 mm to ~0.11 mm at given parameters. (4) In thermomechanical simulations, the results revealed that decreasing the powder-bed porosity (50% vs. 35%) can reduce the process temperatures, part residual stresses and overhang deformations. (5) A contact-free heat support beneath an overhang may effectively minimize overhang deformations. (6) The proposed support design methodology may eliminate part overhang deformations using less support materials."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["electronic"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Thermal and thermomechanical studies of beam-based powder-bed additive manufacturing processes"]}]}],"canonical_facts":{"dc:contributor":["Midkiff, K. Clark","Allison, Paul Galon","Barkey, Mark E.","Nastac, Laurentiu"],"dc:contributor.advisor":["Chou, Y. 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The primary objectives of this research are: (1) to develop a 3D finite element (FE) thermal model to study the powder porosity effect in EBAM, validated by near infrared thermography; (2) to apply the developed thermal model and study, supported by experiments, the thermal response under different process parameters; (3) to simulate the SLM process using the developed 3D thermal model; (4) to develop a 3D thermomechanical FE model to study temperature, stress and deformation characteristics in EBAM overhang parts for different powder sintering conditions; (5) to investigate different support structures for overhang deformation in EBAM; (6) to investigate an overhang support design method for structure optimization. The major findings are summarized as follows. (1) For beam process parameters of 632 mm/s speed, 6.7 mA current and 0.55 mm diameter, the peak temperature is ~2700 °C and melt pool size is 2.94 × 1.09 × 0.12 mm (length, width and depth). (2) Process parameters affect thermal characteristics. For 482 vs. 1595 mm/s speed, given 7.7 mA current and 0.65 mm diameter, the peak temperatures are 2572 vs. 2326 °C and the melt pool lengths are 2.35 vs. 1.25 mm. (3) In SLM, the residual heat can increase the melt pool size from raster scanning; e.g., the melt pool depth changes from ~0.085 mm to ~0.11 mm at given parameters. (4) In thermomechanical simulations, the results revealed that decreasing the powder-bed porosity (50% vs. 35%) can reduce the process temperatures, part residual stresses and overhang deformations. (5) A contact-free heat support beneath an overhang may effectively minimize overhang deformations. (6) The proposed support design methodology may eliminate part overhang deformations using less support materials."],"dc:format.medium":["electronic"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["u0015_0000001_0002503","Cheng_alatus_0004D_12950"],"dc:identifier.uri":["http://ir.ua.edu/handle/123456789/3136"],"dc:language":["English"],"dc:language.iso":["en_US"],"dc:publisher":["University of Alabama Libraries"],"dc:rights":["All rights reserved by the author unless otherwise indicated."],"dc:subject":["Mechanical engineering"],"dc:title":["Thermal and thermomechanical studies of beam-based powder-bed additive manufacturing processes"],"dc:type":["thesis","text"]},"updated_at":"2026-07-27T18:44:20Z"}