Unstable crack advance across a regular array of short fibers in brittle matrix

The resistance to cleavage cracking of a regular array of short fibers was discussed through R-curve analysis. The final failure of the fiber array associated with the unstable crack advance across it occurred when the balance of the rates of the energy release rate and the fracture resistance was reached. The fracture resistance dominated by the combined bridging effect and crack trapping effect increased with the volume fraction and the aspect ratio of the fibers, as well as the internal friction. The toughening effect strongly depended on the crack length for short cracks but was size insensitive for long cracks. The elastic properties of the matrix had little influence on the overall fracture resistance.