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Experimental Study of Creep Behaviour of Two Dimensional Kevlar Braided Composites

  • Author / Creator
    Ead, Ahmed
  • Creep is defined as the “progressive deformation of a material with time under constant load” and is of primary concern in structural design. This research sought to study the creep behaviour of braided composites. This information could be used to infer how fiber reinforced polymer (FRP) rebars, with a braided overwrap, would behave when used in structural design as an alternative to steel. To study the creep behaviour, braided composites were manufactured from Kevlar® 49 and Epon 826 epoxy resin at three braid angles, 35o, 45o and 55o. To assess the creep behaviour, samples were loaded to three different percentages of their failure load, 40%, 50% and 60%. The strain-time curves produced from the strain data showed that the samples did exhibit creep behaviour. It was found that all samples loaded to 40% of the failure did not fail during the test time but maintained a steady creep rate. As the percentage loading increased, the strain experienced by the samples increased. 35o braids at 40% were found to be the most durable with a projected endurance limit greater than 15 years. For the 45o and 55o braids, the endurance limit was lower. 45o braided composites at 50% and 60% of the fracture load failed during the tests performed, exhibiting a lower endurance limit. This study is the first to assess creep of braided composites. Findings show that the braided overwrap in an FRP may be a limiting factor at higher loads, but judicious design choices in loading, braid geometry and core material should alleviate concerns.

  • Subjects / Keywords
  • Graduation date
    Fall 2018
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R35Q4S28F
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.