Damage evolution in braided composite tubes under torsion studied by in-situ X-ray computed tomography

Yuan Chai, Ying Wang, Zeshan Yousaf, Nghia T. Vo, Tristan Lowe, Prasad Potluri, Philip J. Withers

Research output: Contribution to journalArticlepeer-review

Abstract

Here we present the first real-time three dimension (3D) observations of damage evolution in a composite tube under torsion. An in-situ torsion test of 1/1 45° (diamond) braided carbon fibre-epoxy circular composite tube was performed on a loading rig and the damage process was characterised by synchrotron X-ray computed tomography (CT). A number of damage modes and their damage sequence has been identified and monitored globally and in more detail within a representative region of interest. In particular, intra-tow cracks and inter-tow debonding have been found to occur almost simultaneously at low shear strains (1.5%). It is noteworthy that inter-tow debonding was initially trapped/limited within repeated braid units before propagating and connecting with other damage modes in 3D. The area fraction of inter-tow debonds was quantified at different stages and it was found to dramatically increase with increasing shear strain beyond 1.5%. The total volume fraction of the observed intra-tow cracks of various forms was seen to grow rapidly beyond shear strain of 2.0%. Beyond the peak shear stress (at shear strain of 2.5%), fibre micro-buckling and kink bands occur in the tows subjected to torsion induced axial compression at crimped regions close to tow crossovers. Tow crossovers control many aspects of damage propagation under torsion, positively by localising inter-tow debonds and negatively by initiating fibre micro-buckling.
Original languageEnglish
Article number107976
Pages (from-to)1-9
Number of pages9
JournalComposites Science and Technology
Volume188
Early online date28 Dec 2019
DOIs
Publication statusPublished - 2020

Keywords

  • Textile composites
  • Damage mechanics
  • Non-destructive testing
  • Time-lapse
  • Braiding

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