Strain rate effects on the anisotropic behavior of unidirectional CVI SiC f ${\rm SiC}_{\mathrm{f}}$ /PyC/SiC composites

In this paper, we examined the dynamic behaviors of unidirectional (UD) ${\mathrm{SiC}}_f$/PyC/SiC composites, fabricated via chemical vapor infiltration (CVI), under various loading conditions. These conditions included tension, compression, and shear, applied in both the longitudinal and transverse directions of the composites. To achieve the desired failure patterns, we designed specific specimens and clamping methods. The tests were conducted using a hydraulic servo testing machine and Kolsky tension and compression bar systems to achieve different loading rates. Post-test specimens' typical microstructural characteristics, such as matrix cracks, fiber breakages, and fracture angles, were observed using optical and scanning electron microscopy (SEM). By combining these characteristics with the mechanical responses, we investigated the damage mechanisms and effects of strain rate. Finally, based on the experimental results, we discussed precautions for ceramic matrix composites (CMCs) during manufacturing and service processes.