Microstructure Influence on Energy Dissipation in Particle-Reinforced Ceramic Matrix Composites Under Impact Loading

Ceramic matrix composites are important in applications that require high resistance to impact loading. The performance of these material systems is directly related to microstructural attributes. In this research, a mesoscale computational framework based on the cohesive finite element method (CFEM) is used to analyze the dynamic fracture, fragmentation, contact, and interfacial friction in ceramic composites under high-rate impact loading. The focus of the analysis is on characterizing the fracture and frictional energy dissipation over a range of impact loading. The model captures the effects of microstructure constituent distribution, intergranular and transgranular fracture, and friction between crack faces. Arbitrary fracture patterns and energy dissipation at fracture/friction sites within and between the different constituents are explicitly resolved and tracked. The material studied consists of TiB₂ reinforcement embedded in an Al₂O₃ matrix. A range of microstructure morphologies are generated and analyzed, with quantification of uncertainties arising from random variations at the microstructure level. The influences of phase size and phase volume fraction are delineated. Available data from impact experiments is used to calibrate the cohesive model parameters. The results obtained demonstrate that the distribution of TiB₂ grains has a significant effect on overall energy dissipation. A higher volume fraction of TiB₂ and larger TiB₂ grain size lead to higher energy dissipation capability of the material. Although one material system is analyzed, the framework presented is applicable to other material systems in terms of selecting combinations of phase size and volume fraction that enhance energy dissipation under high-rate impact loading.