In Situ Tomography of Microcracking in Cross Ply Carbon Fiber Composites with Pre-existing Debonding Damage

Handle URI:
http://hdl.handle.net/10754/235331
Title:
In Situ Tomography of Microcracking in Cross Ply Carbon Fiber Composites with Pre-existing Debonding Damage
Authors:
Traudes, Daniel
Abstract:
Carbon fiber based composites are an essential material in weight-critical applications such as in the aerospace industry. However, these materials are susceptible to damage such as matrix microcracking and fiber/matrix debonding (diffuse damage), which occurs at stresses much lower than the failure stress. A T700/M21 [0/90]s laminate was tensile loaded to introduce diffuse damage and prepared for a study on the initiation of transverse microcracks. The material was tensile loaded in a [+45/-45]s orientation to induce diffuse damage. A diffuse damage indicator was developed by measuring the decrease in shear stiffness. Samples with diffuse damage levels of 0, 0.05, 0.10, 0.15, 0.20, and 0.25 were prepared to be tensile tested in a [0/90]s orientation to induce microcracks. A successful development of the microcracking test procedure was performed. The edge of the material was studied with optical microscopy and x-ray to establish the structure of the fiber bundle geometry when undamaged. A sample containing microcracks was treated with diiodomethane dye penetrant, which successfully highlighted microcracks during x-ray imaging. The application time was not sufficient to produce consistent x-ray images over time, so a 45 minute soak time was recommended instead. The same damaged sample was subjected to a tomographic scan without a dye penetrant and while unloaded. Transverse microcracks were successfully identified from the data, although the results were not clean enough and likely omitted some smaller microcracks. Results are expected to be cleaner if performed during tensile testing. Future tensile testing will quantify the induced crack density of samples containing various degrees of initial diffuse damage, either using x-rays with a dye penetrant or using x-ray microtomography.
Advisors:
Lubineau, Gilles ( 0000-0002-7370-6093 )
Committee Member:
Amassian, Aram ( 0000-0002-5734-1194 ) ; Farooq, Aamir ( 0000-0001-5296-2197 )
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Mechanical Engineering
Issue Date:
Jul-2012
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorLubineau, Gillesen
dc.contributor.authorTraudes, Danielen
dc.date.accessioned2012-07-24T06:55:17Z-
dc.date.available2012-07-24T06:55:17Z-
dc.date.issued2012-07en
dc.identifier.urihttp://hdl.handle.net/10754/235331en
dc.description.abstractCarbon fiber based composites are an essential material in weight-critical applications such as in the aerospace industry. However, these materials are susceptible to damage such as matrix microcracking and fiber/matrix debonding (diffuse damage), which occurs at stresses much lower than the failure stress. A T700/M21 [0/90]s laminate was tensile loaded to introduce diffuse damage and prepared for a study on the initiation of transverse microcracks. The material was tensile loaded in a [+45/-45]s orientation to induce diffuse damage. A diffuse damage indicator was developed by measuring the decrease in shear stiffness. Samples with diffuse damage levels of 0, 0.05, 0.10, 0.15, 0.20, and 0.25 were prepared to be tensile tested in a [0/90]s orientation to induce microcracks. A successful development of the microcracking test procedure was performed. The edge of the material was studied with optical microscopy and x-ray to establish the structure of the fiber bundle geometry when undamaged. A sample containing microcracks was treated with diiodomethane dye penetrant, which successfully highlighted microcracks during x-ray imaging. The application time was not sufficient to produce consistent x-ray images over time, so a 45 minute soak time was recommended instead. The same damaged sample was subjected to a tomographic scan without a dye penetrant and while unloaded. Transverse microcracks were successfully identified from the data, although the results were not clean enough and likely omitted some smaller microcracks. Results are expected to be cleaner if performed during tensile testing. Future tensile testing will quantify the induced crack density of samples containing various degrees of initial diffuse damage, either using x-rays with a dye penetrant or using x-ray microtomography.en
dc.language.isoenen
dc.subjectCompositesen
dc.subjectTomographyen
dc.subjectIn situen
dc.subjectDiffuseen
dc.subjectCFRPen
dc.subjectMicrocracken
dc.titleIn Situ Tomography of Microcracking in Cross Ply Carbon Fiber Composites with Pre-existing Debonding Damageen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberAmassian, Aramen
dc.contributor.committeememberFarooq, Aamiren
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.nameMaster of Scienceen
dc.person.id113206en
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