To investigate the effect of cooling holes on strength of ceramic matrix composites, three kinds of 2.5D SiC-PyC-SiC composite specimens with cooling holes were designed, including the 90° single cooling hole specimen, the 45° single cooling hole specimen and the 45° multi-cooling hole specimen. Tensile mechanical tests were carried out at 1 100 ℃ air atmosphere, and the appearance of fractures was observed by scanning electron microscope. The experimental results demonstrated that under tensile loads, the ultimate strength of specimens from high to low in order were: the 90° single cooling hole specimen, the 45° single cooling hole specimen, the 45° multi-cooling hole specimen. The fracture locations of the three kinds of specimens were basically in the plane parallel to the axis of the cooling hole. Stress analysis of specimens revealed: the maximum stress near the cooling hole of the 45° single cooling hole specimen was lower than that of the 90° single cooling hole specimen, however its global stress level was higher than that of the 90° single cooling hole specimen, which causes the 45° single cooling hole specimen had a lower failure strength. And the fracture location of the 45° multi-cooling holes specimen was consistent with the distribution of large stress.
Cui et al. (Sun,) studied this question.