{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/83926"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/83926","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Micromechanics of Hydrogen-Induced Crack Initiation in Pipeline Steels and Subcritical Crack Growth","abstract":"To further explore the influence of hydrogen on ductile fracture, we model sustained-load cracking in the iron-base superalloy 1N903 at hydrogen pressures at which fracture is governed by plasticity. Through a micromechanics analysis, we quantify the void growth dependence on stress triaxiality and hydrogen-induced material softening as a function of position ahead of a crack tip. Correlation of the calculated void diameters with experimentally measured ones leads to the identification of a microstructural length that characterizes the onset of hydrogen-induced cracking. Lastly, to analyze the mechanics of sustained-load cracking at pressures greater than 100 MPa for which experiments suggest that hydrogen promotes failure by intergranular cracking, we simulate crack propagation by cohesive finite element methodology based on hydrogen-induced decohesion thermodynamics. The results reveal a number of issues related to the complexity of the failure mechanism and the robustness of the cohesive element approach.","abstract_html":"To further explore the influence of hydrogen on ductile fracture, we model sustained-load cracking in the iron-base superalloy 1N903 at hydrogen pressures at which fracture is governed by plasticity. Through a micromechanics analysis, we quantify the void growth dependence on stress triaxiality and hydrogen-induced material softening as a function of position ahead of a crack tip. Correlation of the calculated void diameters with experimentally measured ones leads to the identification of a microstructural length that characterizes the onset of hydrogen-induced cracking. Lastly, to analyze the mechanics of sustained-load cracking at pressures greater than 100 MPa for which experiments suggest that hydrogen promotes failure by intergranular cracking, we simulate crack propagation by cohesive finite element methodology based on hydrogen-induced decohesion thermodynamics. The results reveal a number of issues related to the complexity of the failure mechanism and the robustness of the cohesive element approach.","abstract_has_math":false,"creators":["Dadfarnia, Mohsen"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Sofronis, Petros"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-25T21:12:44Z","date_published":"2015-09-25T21:12:44Z","updated_at":"2026-07-22T22:26:22Z","subjects":["Engineering, Metallurgy"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI3362764"],"render_values":[{"text":"(MiAaPQ)AAI3362764","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/83926","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Sofronis, Petros"]},{"key":"dc:creator","label":"Author","values":["Dadfarnia, Mohsen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-25T21:12:44Z","10000-01-01","2009"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Metallurgy"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/83926","(MiAaPQ)AAI3362764"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["To further explore the influence of hydrogen on ductile fracture, we model sustained-load cracking in the iron-base superalloy 1N903 at hydrogen pressures at which fracture is governed by plasticity. Through a micromechanics analysis, we quantify the void growth dependence on stress triaxiality and hydrogen-induced material softening as a function of position ahead of a crack tip. Correlation of the calculated void diameters with experimentally measured ones leads to the identification of a microstructural length that characterizes the onset of hydrogen-induced cracking. Lastly, to analyze the mechanics of sustained-load cracking at pressures greater than 100 MPa for which experiments suggest that hydrogen promotes failure by intergranular cracking, we simulate crack propagation by cohesive finite element methodology based on hydrogen-induced decohesion thermodynamics. The results reveal a number of issues related to the complexity of the failure mechanism and the robustness of the cohesive element approach.","Made available in DSpace on 2015-09-25T21:12:44Z (GMT). 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Through a micromechanics analysis, we quantify the void growth dependence on stress triaxiality and hydrogen-induced material softening as a function of position ahead of a crack tip. Correlation of the calculated void diameters with experimentally measured ones leads to the identification of a microstructural length that characterizes the onset of hydrogen-induced cracking. Lastly, to analyze the mechanics of sustained-load cracking at pressures greater than 100 MPa for which experiments suggest that hydrogen promotes failure by intergranular cracking, we simulate crack propagation by cohesive finite element methodology based on hydrogen-induced decohesion thermodynamics. The results reveal a number of issues related to the complexity of the failure mechanism and the robustness of the cohesive element approach.","Made available in DSpace on 2015-09-25T21:12:44Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3362764.pdf: 4641988 bytes, checksum: 8f4452f0eb828914c97227132d318752 (MD5) Previous issue date: 2009","Embargo set by: Seth Robbins for item 85207 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","188 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009."],"dc:identifier":["http://hdl.handle.net/2142/83926","(MiAaPQ)AAI3362764"],"dc:language":["eng"],"dc:subject":["Engineering, Metallurgy"],"dc:title":["Micromechanics of Hydrogen-Induced Crack Initiation in Pipeline Steels and Subcritical Crack Growth"],"dc:type":["text"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:22Z"}