{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/50731"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/50731","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Stability enhancement of a transonic wing using a passive nonlinear energy sink","abstract":"This study examined the use of targeted energy transfer (TET) as a mechanism for passive mitigation of transonic aeroelastic instabilities of a wind-tunnel model wing. Medium- and high-fidelity computational aeroelastic models were used to study the transonic aeroelastic instabilities of the wing and to design a nonlinear energy sink (NES) to enhance stability. Several flutter-suppression mechanisms were identified and it was demonstrated that a properly designed NES can increase the dynamic pressure at flutter by 15% in the transonic dip. Furthermore, it was shown that only one of the suppression mechanisms is robust enough to survive for a wide variety of initial conditions. Based on an effective NES design identified in the computational aeroelastic study, a prototype winglet-mounted NES was designed and built. Computational aeroelastic analysis of the wing, modeled with the winglet and NES using experimentally identified parameters, showed that the prototype improves aeroelastic stability, but external housings for the NES---like the winglet---must be carefully designed to avoid destabilizing effects. To study how the NES affects the dynamics of the wing, a series of experimental and computational ground vibration tests of the wing were performed. They showed that the NES has a profound effect on the second bending mode of the wing, even for small wingtip oscillations. This is a strong indication that the prototype NES will be effective in wind-tunnel tests, because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the wing. The final part of this work examined some of the challenges associated with algorithm-based design and optimization of an NES for aeroelastic stabilization. Performance metrics were proposed and robust methods by which to evaluate them were developed. The performance metrics and methods were tested by using a multi-objective genetic algorithm to seek effective NES designs. Analysis of the resulting designs and their performance showed that it is possible to identify the nature of aeroelastic responses and quantify the performance of an NES using simple metrics, but more than one is required to do this effectively. Furthermore, the demonstration showed that optimization algorithms can be used with the proposed performance metrics to design effective NESs.","abstract_html":"This study examined the use of targeted energy transfer (TET) as a mechanism for passive mitigation of transonic aeroelastic instabilities of a wind-tunnel model wing. Medium- and high-fidelity computational aeroelastic models were used to study the transonic aeroelastic instabilities of the wing and to design a nonlinear energy sink (NES) to enhance stability. Several flutter-suppression mechanisms were identified and it was demonstrated that a properly designed NES can increase the dynamic pressure at flutter by 15% in the transonic dip. Furthermore, it was shown that only one of the suppression mechanisms is robust enough to survive for a wide variety of initial conditions. Based on an effective NES design identified in the computational aeroelastic study, a prototype winglet-mounted NES was designed and built. Computational aeroelastic analysis of the wing, modeled with the winglet and NES using experimentally identified parameters, showed that the prototype improves aeroelastic stability, but external housings for the NES---like the winglet---must be carefully designed to avoid destabilizing effects. To study how the NES affects the dynamics of the wing, a series of experimental and computational ground vibration tests of the wing were performed. They showed that the NES has a profound effect on the second bending mode of the wing, even for small wingtip oscillations. This is a strong indication that the prototype NES will be effective in wind-tunnel tests, because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the wing. The final part of this work examined some of the challenges associated with algorithm-based design and optimization of an NES for aeroelastic stabilization. Performance metrics were proposed and robust methods by which to evaluate them were developed. The performance metrics and methods were tested by using a multi-objective genetic algorithm to seek effective NES designs. Analysis of the resulting designs and their performance showed that it is possible to identify the nature of aeroelastic responses and quantify the performance of an NES using simple metrics, but more than one is required to do this effectively. Furthermore, the demonstration showed that optimization algorithms can be used with the proposed performance metrics to design effective NESs.","abstract_has_math":false,"creators":["Hubbard, Sean"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Aerospace Engineering","degree_department":null,"school":null,"contributors":["Bergman, Lawrence A.","Vakakis, Alexander F.","McFarland, Donald M.","Geubelle, Philippe H.","Masud, Arif"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-09-16T17:25:57Z","date_published":"2014-09-16T17:25:57Z","updated_at":"2026-07-22T22:25:41Z","subjects":["Targeted Energy Transfer","Nonlinear Energy Sink","Computational Transonic Aeroelasticity"],"languages":["en"],"rights":["Copyright 2014 Sean Hubbard"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/50731","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bergman, Lawrence A.","Vakakis, Alexander F.","McFarland, Donald M.","Geubelle, Philippe H.","Masud, Arif"]},{"key":"dc:creator","label":"Author","values":["Hubbard, Sean"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-09-16T17:25:57Z","2014-08","2014-09-16"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Aerospace 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":["Targeted Energy Transfer","Nonlinear Energy Sink","Computational Transonic Aeroelasticity"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2014 Sean Hubbard"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/50731"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This study examined the use of targeted energy transfer (TET) as a mechanism for passive mitigation of transonic aeroelastic instabilities of a wind-tunnel model wing. Medium- and high-fidelity computational aeroelastic models were used to study the transonic aeroelastic instabilities of the wing and to design a nonlinear energy sink (NES) to enhance stability. Several flutter-suppression mechanisms were identified and it was demonstrated that a properly designed NES can increase the dynamic pressure at flutter by 15% in the transonic dip. Furthermore, it was shown that only one of the suppression mechanisms is robust enough to survive for a wide variety of initial conditions. Based on an effective NES design identified in the computational aeroelastic study, a prototype winglet-mounted NES was designed and built. Computational aeroelastic analysis of the wing, modeled with the winglet and NES using experimentally identified parameters, showed that the prototype improves aeroelastic stability, but external housings for the NES---like the winglet---must be carefully designed to avoid destabilizing effects. To study how the NES affects the dynamics of the wing, a series of experimental and computational ground vibration tests of the wing were performed. They showed that the NES has a profound effect on the second bending mode of the wing, even for small wingtip oscillations. This is a strong indication that the prototype NES will be effective in wind-tunnel tests, because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the wing. The final part of this work examined some of the challenges associated with algorithm-based design and optimization of an NES for aeroelastic stabilization. Performance metrics were proposed and robust methods by which to evaluate them were developed. The performance metrics and methods were tested by using a multi-objective genetic algorithm to seek effective NES designs. Analysis of the resulting designs and their performance showed that it is possible to identify the nature of aeroelastic responses and quantify the performance of an NES using simple metrics, but more than one is required to do this effectively. Furthermore, the demonstration showed that optimization algorithms can be used with the proposed performance metrics to design effective NESs.","Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-07-01T13:53:43Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Hubbard_Sean.pdf: 16505741 bytes, checksum: 1d24fa7154047d19b24eaff6f49ac507 (MD5) Hubbard_Sean.pdf: 16505903 bytes, checksum: d93b1efe2e479c7b48bc4156d904ec97 (MD5)","Made available in DSpace on 2014-09-16T17:25:57Z (GMT). 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Several flutter-suppression mechanisms were identified and it was demonstrated that a properly designed NES can increase the dynamic pressure at flutter by 15% in the transonic dip. Furthermore, it was shown that only one of the suppression mechanisms is robust enough to survive for a wide variety of initial conditions. Based on an effective NES design identified in the computational aeroelastic study, a prototype winglet-mounted NES was designed and built. Computational aeroelastic analysis of the wing, modeled with the winglet and NES using experimentally identified parameters, showed that the prototype improves aeroelastic stability, but external housings for the NES---like the winglet---must be carefully designed to avoid destabilizing effects. To study how the NES affects the dynamics of the wing, a series of experimental and computational ground vibration tests of the wing were performed. They showed that the NES has a profound effect on the second bending mode of the wing, even for small wingtip oscillations. This is a strong indication that the prototype NES will be effective in wind-tunnel tests, because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the wing. The final part of this work examined some of the challenges associated with algorithm-based design and optimization of an NES for aeroelastic stabilization. Performance metrics were proposed and robust methods by which to evaluate them were developed. The performance metrics and methods were tested by using a multi-objective genetic algorithm to seek effective NES designs. Analysis of the resulting designs and their performance showed that it is possible to identify the nature of aeroelastic responses and quantify the performance of an NES using simple metrics, but more than one is required to do this effectively. 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