Finite Element Analysis of the Competition Between Crack Deflection and Penetration of Fiber-Reinforced Composites Using Virtual Crack Closure Technique

Crack deflection along the fiber/matrix interface for fiber-reinforced composites is an important condition upon which the toughening mechanisms depend. Sound control for the interface debonding of composites contributes to improving the fracture toughness of composites. Combined with the virtual crack closure technique, a finite element model of composites is proposed to predict the competition between the matrix crack deflection along the interface and the matrix crack penetration into the fibers under the thermomechanical coupling fields. For C/C composites, the effects of the geometry size, fiber volume fraction, fiber coating materials and thermal mismatch on the energy release rate and the crack deflection mechanisms are studied. Results show the fiber coating increases the ability to deflect at large thermal mismatch and small crack sizes, and the TaC coating shows larger effect than the SiC coating. The research provides fundamental method for promoting the toughening design of C/C composites.