Experimental investigation and multiscale simulation on the bending fatigue of SiCf/SiC composite vanes

Abstract

Plain woven composites are widely used in aerospace structures where vibration bending fatigue triggered by uneven airflow is the major failure mode, such as fan blades, turbine vanes, exhaust nozzle seals and etc. In this work, the multiscale fatigue simulation framework validated with composite coupons in previous studies, was investigated for the application to plain woven SiCf/SiC composite vanes. In order to validate the multiscale simulation results, bending fatigue test of the composite vanes was conducted on the basis of a vibration table upgraded with specially designed fixtures, where the in-situ damage images and natural frequency variations of the composite vanes were recorded through the whole fatigue testing process. The macroscopic and mesoscopic damage evolutions revealed by multiscale simulation were in good agreement with the in-situ observed images. Moreover, fatigue life was predicted based on the criterion of natural frequency descending 20%. As a result, the comparison between predicted and experimental fatigue life exhibits a scatter band of ±3.27. This study proves that the developed multiscale simulation method possesses good capability for the bending fatigue damage investigation and life prediction of plain woven composite structures.