{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/78572"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/78572","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"The effect of phase transformation on fatigue crack growth of shape memory alloys","abstract":"The fatigue crack growth of shape memory alloys remains a difficult challenge in the scientific community for years. Most of the works on fatigue crack growth are based on materials that don’t undergo phase transformation when an external force is applied. Consequently, the change of crack tip driven force due to phase transformation is not well understood. In this study, the modification of the crack tip driven force was characterized by the stress intensity factor due to tractions on the transformation zone surface. Through modeling, it was found that the modification became more significant at the maximum applied load than at the minimum in a single load cycle. The effective stress intensity factor range was also measured from the displacement fields upon regression. The predicted effective stress intensity factor range through modeling was later compared with the measured one. The results were found to be closed to each other. The closure effect was also measured and determined to be 30% of the maximum load which corresponded to the modeling results as well. All these agreements confirm the validity of the modeling and pointed to the major mechanical factors such as elastic moduli changes, the transformation residual strains, and the transformation domain dimensions that contribute to damage tolerance in shape memory alloys. The results are checked by conducting simulations for two other important shape memory alloys, NiTi and CuZnAl, where the reductions in stress intensity range were found to be lower than NiFeGa explaining the high levels of experimentally determined crack threshold stress intensity range in NiFeGa.","abstract_html":"The fatigue crack growth of shape memory alloys remains a difficult challenge in the scientific community for years. Most of the works on fatigue crack growth are based on materials that don’t undergo phase transformation when an external force is applied. Consequently, the change of crack tip driven force due to phase transformation is not well understood. In this study, the modification of the crack tip driven force was characterized by the stress intensity factor due to tractions on the transformation zone surface. Through modeling, it was found that the modification became more significant at the maximum applied load than at the minimum in a single load cycle. The effective stress intensity factor range was also measured from the displacement fields upon regression. The predicted effective stress intensity factor range through modeling was later compared with the measured one. The results were found to be closed to each other. The closure effect was also measured and determined to be 30% of the maximum load which corresponded to the modeling results as well. All these agreements confirm the validity of the modeling and pointed to the major mechanical factors such as elastic moduli changes, the transformation residual strains, and the transformation domain dimensions that contribute to damage tolerance in shape memory alloys. The results are checked by conducting simulations for two other important shape memory alloys, NiTi and CuZnAl, where the reductions in stress intensity range were found to be lower than NiFeGa explaining the high levels of experimentally determined crack threshold stress intensity range in NiFeGa.","abstract_has_math":false,"creators":["Wu, Yan"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-07-22T22:18:22Z","date_published":"2015-07-22T22:18:22Z","updated_at":"2026-07-22T22:26:11Z","subjects":["Shape Memory Alloys","Fatigue Crack Growth"],"languages":["en"],"rights":["Copyright 2015 Yan Wu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/78572","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Wu, Yan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-07-22T22:18:22Z","2015-05","2015-05-01","2015-5"]},{"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":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Shape Memory Alloys","Fatigue Crack Growth"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2015 Yan Wu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/78572"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The fatigue crack growth of shape memory alloys remains a difficult challenge in the scientific community for years. Most of the works on fatigue crack growth are based on materials that don’t undergo phase transformation when an external force is applied. Consequently, the change of crack tip driven force due to phase transformation is not well understood. In this study, the modification of the crack tip driven force was characterized by the stress intensity factor due to tractions on the transformation zone surface. Through modeling, it was found that the modification became more significant at the maximum applied load than at the minimum in a single load cycle. The effective stress intensity factor range was also measured from the displacement fields upon regression. The predicted effective stress intensity factor range through modeling was later compared with the measured one. The results were found to be closed to each other. The closure effect was also measured and determined to be 30% of the maximum load which corresponded to the modeling results as well. All these agreements confirm the validity of the modeling and pointed to the major mechanical factors such as elastic moduli changes, the transformation residual strains, and the transformation domain dimensions that contribute to damage tolerance in shape memory alloys. The results are checked by conducting simulations for two other important shape memory alloys, NiTi and CuZnAl, where the reductions in stress intensity range were found to be lower than NiFeGa explaining the high levels of experimentally determined crack threshold stress intensity range in NiFeGa.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Yan Wu, accepted the attached license on 2015-05-01 at 11:27.","The student, Yan Wu, submitted this Thesis for approval on 2015-05-01 at 11:33.","This Thesis was approved for publication on 2015-05-01 at 15:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8228 on 2015-07-22 at 10:35:19","Made available in DSpace on 2015-07-22T22:18:22Z (GMT). No. of bitstreams: 2 WU-THESIS-2015.pdf: 3622380 bytes, checksum: 962d5499577801935ef748a758dc45fb (MD5) LICENSE.txt: 4203 bytes, checksum: b83acb663310def35f59812582ebb01b (MD5) Previous issue date: 2015-05-01"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effect of phase transformation on fatigue crack growth of shape memory alloys"]}]}],"canonical_facts":{"dc:creator":["Wu, Yan"],"dc:date":["2015-07-22T22:18:22Z","2015-05","2015-05-01","2015-5"],"dc:description":["The fatigue crack growth of shape memory alloys remains a difficult challenge in the scientific community for years. Most of the works on fatigue crack growth are based on materials that don’t undergo phase transformation when an external force is applied. Consequently, the change of crack tip driven force due to phase transformation is not well understood. In this study, the modification of the crack tip driven force was characterized by the stress intensity factor due to tractions on the transformation zone surface. Through modeling, it was found that the modification became more significant at the maximum applied load than at the minimum in a single load cycle. The effective stress intensity factor range was also measured from the displacement fields upon regression. The predicted effective stress intensity factor range through modeling was later compared with the measured one. The results were found to be closed to each other. The closure effect was also measured and determined to be 30% of the maximum load which corresponded to the modeling results as well. All these agreements confirm the validity of the modeling and pointed to the major mechanical factors such as elastic moduli changes, the transformation residual strains, and the transformation domain dimensions that contribute to damage tolerance in shape memory alloys. The results are checked by conducting simulations for two other important shape memory alloys, NiTi and CuZnAl, where the reductions in stress intensity range were found to be lower than NiFeGa explaining the high levels of experimentally determined crack threshold stress intensity range in NiFeGa.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms","The student, Yan Wu, accepted the attached license on 2015-05-01 at 11:27.","The student, Yan Wu, submitted this Thesis for approval on 2015-05-01 at 11:33.","This Thesis was approved for publication on 2015-05-01 at 15:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8228 on 2015-07-22 at 10:35:19","Made available in DSpace on 2015-07-22T22:18:22Z (GMT). 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