Bridging fiber stress distribution during fatigue crack growth in [0]4 SCS-6/timetal®21S

Geometric correction factors determined by force balance method for center cracked specimens

“…Such a case and the previously considered cases [2] may be used to account for fatigue crack closure effects, extrinsic toughening mechanisms like zone shielding and contact shielding [3,4], crack-face cohesive forces and/or bridging stresses in composite materials [5-10]• There are several types of crack bridging models in brittle-matrix fiber-reinforced composite materials, such as constant bridging stress [10], shear lag [11][12][13], fiber pressure [14] models. In other words, the bridging stress is linearly distributed in the fiber pressure model and is zero at the crack tip in the shear lag model [14][15][16]. The geometric correction factor for this case has been deduced in Part VIII [2].…”

“…Obviously, in the constant bridging stress model the bridging stress was assumed to be unchanged over the entire bridged area. In other words, the bridging stress is linearly distributed in the fiber pressure model and is zero at the crack tip in the shear lag model [14][15][16]. In both the shear lag and the fiber pressure models, the bridging stress increases with increasing distance from the crack tip.…”