Results are presented on the fatigue behavior of continuous fiber-reinforced aluminum and titanium alloys, both reinforced with SiC fibers. The pure aluminum matrix was reinforced with the “Tyranno” fiber of Ube, Japan, while the Ti6Al4V matrix was reinforced with the SCS-6 fiber of Textron. Also investigated was an Al-2.5Li alloy reinforced with α-Al2O3 FP fiber from DuPont.
The fatigue behavior of the MMC composites was observed to be superior when compared to the fatigue behavior of bulk matrix material. This was especially true for the case of tension-compression loading, where the overall superior compressive behavior of MMCs played a dominant role.
Failure in an MMC with unidirectional reinforcement normally initiates at or near imperfections, such as misaligned fibers, voids, foreign inclusions, or surface damage with subsequent fatigue crack propagation. An answer is given as to whether the variation of stiffness due to damage development can be used as a damage analogue. Finally, an explanation of the fracture behavior is given.