Residual strength degradation of a titanium matrix composite subjected to elevated temperature fatigue

Most of the experimental fatigue studies performed on Titanium Matrix Compo site (TMC) systems have subjected the test specimens to complete failure. U nfortunately, this type of investigation provides little information about the progression of damage mechanisms or the residual strength degradation o f the material. To address this concern, an experimental test program was c onducted on SCS-6/Ti-15-3 composite with laminate orientations of [0](8), [ 0/90](2s), and [0/+/-45/90](s). The main goal of this research was to deter mine the effect of elevated-temperature (427 degrees C) fatigue on the degr adation of residual strength in TMCs. Specimens were cycled until they had reached a pre-determined percentage of their fatigue life. After cycling, s pecimens were loaded monotonically in tension until failure. Fractography o f the specimens provided information pertaining to the progression of damag e mechanisms during fatigue. The laminate orientation was the primary facto r for controlling the damage progression morphology as well as the residual strength degradation.