Session: 02-01 Mechanical Behavior of Ceramics & Composites

Paper Number: 80583

80583 - Micromechanical Modeling of Time-Dependent Crack Opening Behavior in SiC/SiC Composites 

Ceramic-matrix composites possess high specific strength and modulus at elevated temperature and have already been applied in hot-section components in commercial or military gas turbine engines. Due to low fracture strain in the brittle SiC ceramic, matrix microcracking occurs below the proportional limit stress. At elevated temperature, the opening of matrix microcracking affects the mechanical properties of ceramic-matrix composites (CMCs) when the oxygen or oxidative gas ingresses the composite through these cracks. To ensure the reliability, safety, and airworthiness level of CMCs components, it is necessary to understand the crack opening behavior of CMCs at elevated temperature. In this paper, a micromechanical approach is developed to predict the time-dependent crack opening behavior in SiC/SiC composite. Micro stress field in the different damage regions, i.e., interface oxidation region, interface slip region, and interface bonding region, are obtained and the axial fiber displacement (AFD), axial matrix displacement (AMD), and cracking opening displacement (COD) are calculated. Experimental CODs in SiC/SiC composite for different matrix crack lengths are predicted. Effects of fiber volume fraction, stress level, interface properties on time-dependent crack opening behavior (e.g., AFD, AMD, COD, and crack opening stress (COS)) in SiC/SiC composite are analyzed. Relationships between the cracking opening, composite’s constituent properties, and stress level are established. The analysis results can help the engineering designer better understanding the crack opening behavior in CMCs.

Presenting Author: Longbiao Li Nanjing University of Aeronautics and Astronautics

Presenting Author Biography: Dr. Longbiao Li is a lecturer in the College of Civil Aviation at the Nanjing University of Aeronautics and Astronautics. Dr. Li’s research focuses on the vibration, fatigue, damage, fracture, reliability, safety and durability of aircraft and aero engine. In this research area, he is the first author of 177 SCI journal publications (46 JCR Q1), 8 monograph, 3 edited book, 3 text book, 3 book chapters, 30 Chinese Patents, 2 US Patents, 2 Chinese Software Copyright, and more than 20 refereed conference proceedings. He has been involved in different projects related to structural damage, reliability, and airworthiness design for aircraft and aero engines, supported by the Natural Science Foundation of China, COMAC Company, and AECC Commercial Aircraft Engine Company.

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