{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/34503"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/34503","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Mechanical Properties of Random Discontinuous Fiber Composites Manufactured from Wetlay Process","abstract":"The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that included the set-point mold pressure, set-point mold temperature and cooling methods. The fibers used in the study included glass and carbon fiber. Polypropylene (PP) and Polyethylene Terephthalate (PET) were used as the matrix. Glass/PP and Glass/PET plaques that had fiber volume fractions ranging from 0.05 to 0.50 at an increment of 0.05 were molded. Both tensile and flexural tests were conducted. The test results showed a common pattern, i.e., the modulus and strength of the composite increased with the fiber volume fraction to a maximum and then started to descend. The test results were analyzed to find out the optimal fiber volume fraction that yielded the maximum modulus or strength. Carbon/PET composites plaques were also molded to compare their properties with Glass/PET composite at similar fiber volume fractions. Micrographs were taken of selected specimens to examine the internal structure of the material. Existing micromechanics models that predict the tensile modulus or strength of random fiber composites were examined. Predictions from some of the models were compared with test data.","abstract_html":"The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that included the set-point mold pressure, set-point mold temperature and cooling methods. The fibers used in the study included glass and carbon fiber. Polypropylene (PP) and Polyethylene Terephthalate (PET) were used as the matrix. Glass/PP and Glass/PET plaques that had fiber volume fractions ranging from 0.05 to 0.50 at an increment of 0.05 were molded. Both tensile and flexural tests were conducted. The test results showed a common pattern, i.e., the modulus and strength of the composite increased with the fiber volume fraction to a maximum and then started to descend. The test results were analyzed to find out the optimal fiber volume fraction that yielded the maximum modulus or strength. Carbon/PET composites plaques were also molded to compare their properties with Glass/PET composite at similar fiber volume fractions. Micrographs were taken of selected specimens to examine the internal structure of the material. Existing micromechanics models that predict the tensile modulus or strength of random fiber composites were examined. Predictions from some of the models were compared with test data.","abstract_has_math":false,"creators":["Lu, Yunkai"],"institution":"Virginia Tech","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":["Loos, Alfred C."],"committee_members":["Batra, Romesh C.","Hyer, Michael W."],"year":2002,"date_issued":"2002-08-06","date_published":"2002-08-06","updated_at":"2026-07-22T22:19:10Z","subjects":["micromechanics","molding cycle","discontinuous","fiber reinforced composite","random","wetlay process"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08132002-163349"],"render_values":[{"text":"etd-08132002-163349","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/34503","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Loos, Alfred C."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Batra, Romesh C.","Hyer, Michael W."]},{"key":"dc:contributor.department","label":"Department","values":["Engineering Science and Mechanics"]},{"key":"dc:creator","label":"Author","values":["Lu, Yunkai"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:43:21Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:43:21Z","2003-08-22"]},{"key":"dc:date.issued","label":"Date","values":["2002-08-06"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"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":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["micromechanics","molding cycle","discontinuous","fiber reinforced composite","random","wetlay process"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"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.other","label":"Dc Identifier Other","values":["etd-08132002-163349"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/34503"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that included the set-point mold pressure, set-point mold temperature and cooling methods. The fibers used in the study included glass and carbon fiber. Polypropylene (PP) and Polyethylene Terephthalate (PET) were used as the matrix. Glass/PP and Glass/PET plaques that had fiber volume fractions ranging from 0.05 to 0.50 at an increment of 0.05 were molded. Both tensile and flexural tests were conducted. The test results showed a common pattern, i.e., the modulus and strength of the composite increased with the fiber volume fraction to a maximum and then started to descend. The test results were analyzed to find out the optimal fiber volume fraction that yielded the maximum modulus or strength. Carbon/PET composites plaques were also molded to compare their properties with Glass/PET composite at similar fiber volume fractions. Micrographs were taken of selected specimens to examine the internal structure of the material. Existing micromechanics models that predict the tensile modulus or strength of random fiber composites were examined. Predictions from some of the models were compared with test data."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Mechanical Properties of Random Discontinuous Fiber Composites Manufactured from Wetlay Process"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Loos, Alfred C."],"dc:contributor.committeemember":["Batra, Romesh C.","Hyer, Michael W."],"dc:contributor.department":["Engineering Science and Mechanics"],"dc:creator":["Lu, Yunkai"],"dc:date.accessioned":["2014-03-14T20:43:21Z"],"dc:date.available":["2014-03-14T20:43:21Z","2003-08-22"],"dc:date.issued":["2002-08-06"],"dc:description.abstract":["The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that included the set-point mold pressure, set-point mold temperature and cooling methods. The fibers used in the study included glass and carbon fiber. Polypropylene (PP) and Polyethylene Terephthalate (PET) were used as the matrix. Glass/PP and Glass/PET plaques that had fiber volume fractions ranging from 0.05 to 0.50 at an increment of 0.05 were molded. Both tensile and flexural tests were conducted. The test results showed a common pattern, i.e., the modulus and strength of the composite increased with the fiber volume fraction to a maximum and then started to descend. The test results were analyzed to find out the optimal fiber volume fraction that yielded the maximum modulus or strength. Carbon/PET composites plaques were also molded to compare their properties with Glass/PET composite at similar fiber volume fractions. Micrographs were taken of selected specimens to examine the internal structure of the material. Existing micromechanics models that predict the tensile modulus or strength of random fiber composites were examined. Predictions from some of the models were compared with test data."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-08132002-163349"],"dc:identifier.uri":["http://hdl.handle.net/10919/34503"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["micromechanics","molding cycle","discontinuous","fiber reinforced composite","random","wetlay process"],"dc:title":["Mechanical Properties of Random Discontinuous Fiber Composites Manufactured from Wetlay Process"],"dc:type":["Thesis"],"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":"2026-07-22T22:19:10Z"}