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

  • braided composites
  • kevlar
  • creep
  • aramid
  • composite materials
  • braiding

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R35Q4S28F

• License

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