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

DOI: 10.1016/j.compscitech.2019.107976 DOI Help

Authors: Yuan Chai (The University of Manchester) , Ying Wang (The University of Manchester) , Zeshan Yousaf (The University of Manchester) , Nghia T. Vo (Diamond Light Source) , Tristan Lowe (The University of Manchester) , Prasad Potluri (The University of Manchester) , Philip J. Withers (The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Composites Science And Technology

State: Published (Approved)
Published: December 2019
Diamond Proposal Number(s): 13704 , 18197

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.

Journal Keywords: Textile composites; Damage mechanics; Non-destructive testing; Time-lapse; Braiding

Subject Areas: Materials, Engineering
Collaborations: Diamond Manchester

Instruments: I13-2-Diamond Manchester Imaging

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