Mechanical properties and failure characteristics of a recycled CFRP under tensile and cyclic loading

• Mechanical properties of new recycled carbon fiber reinforced plastic were examined.
• Tensile strength increased with increasing CFRP content but dropped for the sample with higher fiber content.
• Fatigue strength increased with increasing CFRP content even for the higher fiber sample.
• Fatigue strength of the sample was directly affected by the extent of crack closure.

An examination has been made of the mechanical and failure properties of a recycled short carbon fiber reinforced plastic (rCFRP). The rCFRP samples were fabricated by the following process: the CFRP, consisting of epoxy resin with carbon fiber, is ground before mixing with acrylonitrile butadiene styrene resin with different weight fractions of CFRP. The tensile strength (σUTS) increased with increasing CFRP content, but dropped considerably for the sample with higher fiber content. From in situ measurement of localized failure in rCFRP, it appeared that material failure occurs even if a low tensile stress of 30% σUTS is applied. The localized damage was related to the pull-out (or debonding) of the fibers from the matrix. The fatigue strength increased with increasing the content of the recycled carbon fiber even for the samples with low tensile strength. This was attributed to the low crack driving force arising from severe crack closure. Details of the crack growth behavior were discussed using various crack growth models proposed in previous studies.