Residual Strength Degradation of a Titanium Matrix Composite Subjected to Elevated Temperature Fatigue

Abstract

Most of the experimental fatigue studies performed on Titanium Matrix Composite (TMC) systems have subjected the test specimens to complete failure. Unfortunately, this type of investigation provides little information about the progression of damage mechanisms or the residual strength degradation of the material. To address this concern, an experimental test program was conducted 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 determine the effect of elevated-temperature (427°C) fatigue on the degradation of residual strength in TMCs. Specimens were cycled until they had reached a pre-determined percentage of their fatigue life. After cycling, specimens were loaded monotonically in tension until failure. Fractography of the specimens provided information pertaining to the progression of damage mechanisms during fatigue. The laminate orientation was the primary factor for controlling the damage progression morphology as well as the residual strength degradation. /8/ of damage accumulated during cycling. The damage is typically either matrix or fiber cracking, each of which can have a significant effect on residual strength.