Experimental characterization of fatigue life of ZrB₂-SiC based ultra high-temperature ceramic matrix composites

The development process of new Ultra High-Temperature Ceramic Matrix Composites (UHTCMC) for use in severe environments typical of space applications, such as thermal protection or rocket components, still lacks useful data for what concerns the properties influencing the structural behavior under the different load conditions. In particular, the fatigue life of the material plays a fundamental role in the design of full systems determining their resistance to typical vibrational loads. However, this property has been rarely investigated for UHTCMCs and its experimental characterization presents uncertainties related to the material specific behavior, which does not allow the application of traditional methodology employed for isotropic materials. In the present work, two different methodologies are proposed and applied to new ZrB₂-SiC-based UHTCMCs, with either short or long continuous fibers, yielding in combination with numerical analyses to the determination of the σ/N curve for the two classes of materials.