Stress mapping reveals extrinsic toughening of brittle carbon fiber in polymer matrix

MDR Open Deposited

We conducted an in situ study on CFRP fracturing process using atomic-force-microscopybased stress-sensitive indentation. Tensile stress distribution during fracture initiation and
propagation was directly observed quantitatively. It led to a discovery that previously believed
catastrophic fracture of individual carbon fiber develops in a controllable manner in the
polymer matrix, exhibiting 10 times increase of fracture toughness. Plastic deformation in
crack-bridging polymer matrix was accounted for the toughening mechanism. The model
was applied to explain low temperature strength weakening of CFRP bulk material when
matrix plasticity was intentionally ‘shut down’ by cryogenic cooling.

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Date published
  • 08/04/2020
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  • Version of record (Published version)