Compression-after-indentation study of alumina-based oxide/oxide ceramic matrix composite with variable damage

In this study, the damage tolerance of alumina-based Oxide/Oxide ceramic matrix composite with varying extent of quasi-static indentation damage is evaluated via compression test. Pre-existing damage in the laminates are of different sizes and exist in the form of delaminations, fiber fracture, matrix cracking, and major throughthickness cracks. Digital image correlation is used to monitor the in-test displacements and strain field. When compared to undamaged compressive strength, the strength reduction in the indented specimens range from 52 % to 57 %. This shows that the compression after indentation strength is not significantly affected by variations in the extent of indentation damage. Digital image correlation results showed out-of-plane deformation originating from the indented region that grew stably with increasing load to a critical phase, beyond which they became significantly large. This resulted in the sudden catastrophic failure of the laminate, apparently caused by delamination buckling. This was confirmed by post-test X-ray computed tomography micrographs.