Evaluation of transverse crack propagation and accumulation of carbon fiber reinforced plastics

In this paper, we evaluated transverse crack propagation and accumulation of CFRP laminates with kidney-shape carbon fibers by experimental and computational micromechanics. We investigated the effect of a cross-sectional shape of carbon fibers on the transverse crack density by the tensile tests of cross-ply laminates with round-shape and kidney-shape carbon fibers. We temporarily interrupted the tests and measured the crack density by replica method when the tensile strain reached specific values. Experimental results showed that the CFRP laminates with kidney-shape carbon fibers have a smaller increasing rate and larger variation of the crack density than those with round-shape carbon fibers. In order to consider the difference in crack propagation depending on the fiber cross-sectional shape, we carried out elastic-plastic damage analysis by finite element analysis. In the CFRP model with round-shape carbon fibers, the major failure mode is damages on fiber/matrix interface. On the other hand, the major failure mode of the CFRP model with kidney-shape carbon fibers is damages on matrix resin. The simulation results agreed well with experimental results about the increasing rate and the variation of the crack density.