A Durability and Damage Tolerance (D&DT) analysis of an S200 Nicalon/SiNC and Oxide/Oxide Ceramic Matrix Composite (CMC) was conducted to determine the crack growth resistance (GIc) of Wedge Loaded DCB (WDCB) at Room and Elevated temperatures (RT/ET) and compared with experimental tests observations. Wedge Loading gives proper crack path without mixed mode effects and can be used at high temperature in a furnace. Load displacement, GIc, electrical resistivity and acoustic emission was measured by tests and compared to FE based Multi Scale Progressive Failure Analysis (PFA) of the WDCB specimen. The critical damage events studied included damage initiation, damage propagation, fracture initiation, and fracture propagation as the components were being loaded.
Effect of defects on Modulus (E11, E22, and E33) was conducted by Electrical Resistance (ER) Measurement at Room temperature (RT). Multi-Scale modeling simulation considered de-homogenized nano-assisted micromechanics analytical formulation, a Mori Tanaka based stiffness correction including void shape, size, distribution and orientation effects. Emitted/received signal amplitude by ER Vs. time was used to evaluate reduction of stiffness in all directions resulting in anisotropic stiffness of As-Built specimens. WDCB specimen was tested to failure at RT/ET to produce reliable GIc values with minimum specimen size. Many parameters that contribute to specimen failure included interface coating thickness, mixed mode failure evolution, interlaminar defects, delamination damage, crack bridging, and fiber fracture which were all studied in detail in this work. All simulations correlated well with test.
