Parametric Analysis of Various Test Configurations for Measuring the Interlaminar Fracture Toughness of CMCs using LayerSlayer and Abaqus

The low weight, excellent durability and heat resistance of ceramic matrix composites (CMCs) make them attractive materials for use in aircraft engine hot sections, where improved overall engine efficiency can be realized. Nevertheless, the interlaminar properties of CMCs must be well understood before CMCs can realistically replace metallic superalloys in engine hot sections, and no standardized test methods for determining interlaminar fracture toughness of CMCs currently exist. During this Phase I effort, Aurora Flight Sciences (AFS) will work closely with experts in CMC fabrication, testing, design, and analysis at the University of California, Santa Barbara (UCSB) and the United Technologies Research Center (UTRC) to develop analytical concept models on interlaminar fracture toughness test methods. A finite element code developed at UCSB, LayerSlayer, will be used in conjunction with the commercially available finite element analysis software, Abaqus, to ascertain stresses, energy release rates and mode mixities in CMCs while conducting parametric studies of various test configurations and geometries feasible for measuring Mode I and Mode II interlaminar fracture toughnesses. Preliminary experiments on CMC specimens will be conducted to evaluate the feasibility of the concept models developed, in preparation for comprehensive testing of several CMC coupons during Phase II.