Relations between intralaminar micromechanisms and translaminar fracture behavior of unidirectional FRP supported by experimental micromechanics Articles uri icon

publication date

  • June 2019

start page

  • 1

end page

  • 11

volume

  • 174

International Standard Serial Number (ISSN)

  • 1359-8368

Electronic International Standard Serial Number (EISSN)

  • 1879-1069

abstract

  • The translaminar fracture behaviors of partially different unidirectional composite systems, constituted by the
    same carbon fibers but different (thermoset vs. thermoplastic) matrices, were characterized by means of compact
    tension fracture tests. The resulting crack resistance curves (R-curves) and fracture surfaces, were studied in
    detail and found to be rather different between those material systems, in spite of the same reinforcing fibers at
    similar volume fractions. In the attempt to justify this difference, the effects of the underlying micromechanisms
    were evaluated by employing experimental micromechanical measurements of the fracture characteristics of
    fibers, matrices and fiber/matrix interfaces. By means of a thorough analysis and quantification of the micromechanisms that contribute to the work of fracture, it was possible to decompose the translaminar fracture
    toughness of the composites into different contributions. Independently of the material considered, fibre bundle
    pull-out was found to be the mechanism that dissipates the highest amount of energy. Different patterns of
    bundle pull-out in different material systems were found to be the result of different outcomes from the
    competition of fracture micromechanims, and to be responsible for the differences between the translaminar
    fracture energies of both material systems. Moreover, it was realized that the energy dissipated in bundle pullout, hence also the overall measured translaminar fracture toughness are strongly governed by in-situ effects, i.e.
    effects of specimen lamination features.

keywords

  • translaminar fracture; compact tension test; crack resistance (r-curve); micromechanics; fiber; matrix and fiber/matrix interface