Quantification of Foreign Object Damage and Electrical Resistivity for Ceramic Matrix Composites and Tensile Residual Strength Prediction

Abstract

SiC-based ceramic matrix composites (CMC) in turbine engine applications must sustain certain foreign object impacts (FOIs) that might occur in services. Experiments and nondestructive evaluation (NDE) have illustrated good correlations between impact energy and foreign object damage (FOD) assessed using electrical resistivity (ER), acoustic emission (AE), and microscopy. A progressive failure dynamic analysis (PFDA) method is explored in understanding and predicting the damage states, ER, and residual strength after impact of CMCs. To accurately correlate the damage state with ER, the PFDA tool has been improved to incorporate the physical damage mechanisms in CMCs, which are matrix microcrack density due to both longitudinal and transverse tensile loads and the fiber breakage due to probabilistic fiber strength distribution. The predicted damage states and ER are correlated with the measurement of FOD and validated with tension after impact tests using high temperature ER. The PFDA tool has demonstrated a great potential for CMCs' FOD and residual strength predictions.