Yonjig Kim
The Journal of Mechanical Science and Technology, vol. 23, no. 1, pp.8-13, 2009

Abstract : The fracture properties of commercial carbon fiber reinforced carbon (C/C) composites (CCM190C, CCM191C) that have different interfacial shear strength were investigated. Postpeak tension-softening phenomena were observed through the fracture mechanics test for these composites. The failure manner in the fracture process zone was primarily fiber pull-out for CCM190C and fiber breakage for CCM191C, respectively. It was confirmed that the scale of pseudo strain hardening for CCM190C with low interfacial shear strength was larger than that of CCM191C. The bridging energy at the postpeak part and the total energy consumed to produce a unit area of fracture surface were calculated based on the J-based technique. The bridging energy at the postpeak part accounted for 12.3% of the total energy consumed to produce a unit area of fracture surface for CCM190C. From this result, it can be deduced that the effect of the postpeak bridging energy on the fracture toughness is large for CCM190C. In contrast, the contribution of the postpeak bridging energy for the total energy per fracture surface was very small for CCM191C.

Keyword : Postpeak tension-softening relation; Pseudo strain hardening; J-based technique; Fracture process zone; Bridging energy