Fracture mechanisms of fiber-reinforced titanium alloy matrix composites V: Fatigue crack propagation

Abstract

The fatigue crack propagation behavior of several SCS-6 fiber-reinforced titanium alloy matrix composites at room temperature was studied. The testing was conducted in a tension-tension mode on specimens with a chevron notch perpendicular to the fiber direction. The maximum applied stress intensity ranged from 25 to 50 MPa m 1 2 . The fatigue crack growth rates at different applied stress intensity levels were measured. The fatigue damage mechanisms at each testing condition were also identified. Several damage mechanisms were observed at the crack tip including matrix cracking, fiber bridging, crack splitting and crack deflection. The loading conditions. fiber-matrix interfacial shear strength and matrix cracking stress under cyclic loading were the major microstructural parameters controlling the fatigue crack growth behavior. A modified frictional slip model was also to predict the fatigue crack propagation behavior and correlated with experimental results.