{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/71007"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/71007","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"An investigation of stiffness reduction as an indicator of fatigue damage in graphite epoxy composites","abstract":"This investigation concerns the validity and feasibility of using moduli reduction to monitor the effect of fatigue damage in graphite epoxy composites. Five laminate orientations were considered, [O]₄, [90]₄, [±45]<sub>s</sub>, [0,90]<sub>s</sub>, [0,90,±45]<sub>s</sub>, and four inplane-stiffness properties were monitored for each. The stiffness parameters were E<sub>xx</sub>, E<sub>yy</sub>, G<sub>xy</sub>, and v<sub>xy</sub>, and were measured using a longitudinal tension test, a rail shear test and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development. Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue. Longitudinal stiffness (E<sub>xx</sub>) and shear stiffness (G<sub>xy</sub>) were shown to significantly decrease for the [0,90,±45]<sub>s</sub>, laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appears to contribute to the stiffness reductions that occur in the [0,90,±45]<sub>s</sub> laminate.","abstract_html":"This investigation concerns the validity and feasibility of using moduli reduction to monitor the effect of fatigue damage in graphite epoxy composites. Five laminate orientations were considered, [O]₄, [90]₄, [±45]&lt;sub&gt;s&lt;/sub&gt;, [0,90]&lt;sub&gt;s&lt;/sub&gt;, [0,90,±45]&lt;sub&gt;s&lt;/sub&gt;, and four inplane-stiffness properties were monitored for each. The stiffness parameters were E&lt;sub&gt;xx&lt;/sub&gt;, E&lt;sub&gt;yy&lt;/sub&gt;, G&lt;sub&gt;xy&lt;/sub&gt;, and v&lt;sub&gt;xy&lt;/sub&gt;, and were measured using a longitudinal tension test, a rail shear test and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development. Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue. Longitudinal stiffness (E&lt;sub&gt;xx&lt;/sub&gt;) and shear stiffness (G&lt;sub&gt;xy&lt;/sub&gt;) were shown to significantly decrease for the [0,90,±45]&lt;sub&gt;s&lt;/sub&gt;, laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appears to contribute to the stiffness reductions that occur in the [0,90,±45]&lt;sub&gt;s&lt;/sub&gt; laminate.","abstract_has_math":false,"creators":["Camponeschi, Eugene Thomas"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Engineering Science and Mechanics","degree_department":"Engineering Science and Mechanics","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1980,"date_issued":"1980","date_published":"1980","updated_at":"2026-07-22T22:19:38Z","subjects":[],"languages":["en_US"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/71007","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Engineering Science and Mechanics"]},{"key":"dc:creator","label":"Author","values":["Camponeschi, Eugene Thomas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2016-05-23T14:57:03Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2016-05-23T14:57:03Z"]},{"key":"dc:date.issued","label":"Date","values":["1980"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Engineering Science and Mechanics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/71007"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This investigation concerns the validity and feasibility of using moduli reduction to monitor the effect of fatigue damage in graphite epoxy composites. Five laminate orientations were considered, [O]₄, [90]₄, [±45]<sub>s</sub>, [0,90]<sub>s</sub>, [0,90,±45]<sub>s</sub>, and four inplane-stiffness properties were monitored for each. The stiffness parameters were E<sub>xx</sub>, E<sub>yy</sub>, G<sub>xy</sub>, and v<sub>xy</sub>, and were measured using a longitudinal tension test, a rail shear test and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development. Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue. Longitudinal stiffness (E<sub>xx</sub>) and shear stiffness (G<sub>xy</sub>) were shown to significantly decrease for the [0,90,±45]<sub>s</sub>, laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appears to contribute to the stiffness reductions that occur in the [0,90,±45]<sub>s</sub> laminate."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["An investigation of stiffness reduction as an indicator of fatigue damage in graphite epoxy composites"]}]}],"canonical_facts":{"dc:contributor.department":["Engineering Science and Mechanics"],"dc:creator":["Camponeschi, Eugene Thomas"],"dc:date.accessioned":["2016-05-23T14:57:03Z"],"dc:date.available":["2016-05-23T14:57:03Z"],"dc:date.issued":["1980"],"dc:description.abstract":["This investigation concerns the validity and feasibility of using moduli reduction to monitor the effect of fatigue damage in graphite epoxy composites. Five laminate orientations were considered, [O]₄, [90]₄, [±45]<sub>s</sub>, [0,90]<sub>s</sub>, [0,90,±45]<sub>s</sub>, and four inplane-stiffness properties were monitored for each. The stiffness parameters were E<sub>xx</sub>, E<sub>yy</sub>, G<sub>xy</sub>, and v<sub>xy</sub>, and were measured using a longitudinal tension test, a rail shear test and a transverse bend test. Nondestructive testing techniques such as C-scan and edge replication were also performed to aid in the observation of damage development. Results describe the response of each laminate orientation in tension-tension fatigue, including a record of changes in the stiffness properties at intervals during fatigue. Longitudinal stiffness (E<sub>xx</sub>) and shear stiffness (G<sub>xy</sub>) were shown to significantly decrease for the [0,90,±45]<sub>s</sub>, laminate following fatigue loading. The inplane stiffness properties for the other four laminates remain essentially unchanged following fatigue loading. Matrix cracking and delamination appears to contribute to the stiffness reductions that occur in the [0,90,±45]<sub>s</sub> laminate."],"dc:description.degree":["Master of Science"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/71007"],"dc:language.iso":["en_US"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["An investigation of stiffness reduction as an indicator of fatigue damage in graphite epoxy composites"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Engineering Science and Mechanics"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:38Z"}