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Based on shear lag model of interface between fiber and matrix,a new formula that re-lates the crack opening displacement and bridging force in fibrous monolithic ceramics was constructedunder the framework of small scale bridging.This formula was applied to predict the fracture resis-tance or R-curve response of a three-point bending specimen made of fibrous monolithic ceramics.Aparametric investigation on the influences of fiber volume fraction,fiber radius,characteristics ofconstituents,BN’s fracture toughness and specimen’s geometry on the bridging forces and fracture re-sistance in Si_3N_4/BN composite was carried out.The upper and lower limits of the R-curve of Si_3N_4/BN in small scale bridging were derived,This research revealed the role played by the above parame-ters in the fracture toughness of fibrous monolithic ceramics.
Based on shear lag model of interface between fiber and matrix, a new formula that re-lates the crack opening displacement and bridging force in fibrous monolithic ceramics was constructedunder the framework of small scale bridging.This formula was applied to predict the fracture resis- tance or R-curve response of a three-point bending specimen made of fibrous monolithic ceramics. A parametric investigation on the influences of fiber volume fraction, fiber radius, characteristics of ingredients, BN’s fracture toughness and specimen’s geometry on the bridging forces and fracture re-sistance in Si_3N_4 / BN composite was carried out. The upper and lower limits of the R-curve of Si_3N_4 / BN in small scale bridging were derived, This research revealed the role played by the above parame- ters in the fracture toughness of fibrous monolithic ceramics.