Fiber damage mechanisms of SiCf/Ti6242 under fatigue load at elevated temperature

Abstract

A high-temperature fatigue test was conducted on SiCf/Ti6242 composites, and the specimens’ cross-sections were examined using XCT and SEM. A matrix intrusion phenomenon, likely due to fatigue unloading, was noted near the fracture surface. Fiber fragment lengths, fracture spatial distribution, and fiber orientation were analyzed through a novel digital image processing method. Results show that fibers typically break into smaller pieces than predicted by Curtin’s model, concentrating failures in a fan-shaped area. The discrete fiber element model indicates that local off-axis behavior leads to embedding-type fiber fractures, increasing local overload and reducing the composite’s fatigue life. Improvement suggestions are provided for the simulation model of composites with off-axis fibers, along with new requirements for the stacking process of precursor wire-derived composites.