Theoretical Analysis of Small Crack Growth in Fiber-Reinforced Ceramic Composite Materials
Abstract
This research program investigates matrix crack initiation and subsequent propagation in fiber reinforced ceramic materials for use in high temperature structural applications. Though it presents a formidable manufacturing challenge, the inclusion of ceramic fibers promises to increase fracture toughness and improve failure modes through crack deflection, fracture bridging, and frictional interface slip. Experimental observations show that ceramic composites initially fail at several points in the matrix and along the interfaces. These small cracks and inherent processing flaws propagate and coalesce, forming large cracks that lead to component failure. Therefore, an understanding of small crack growth is necessary for the design of composite systems which delay critical crack formation and which fail in a desirable manner. The Surface Integral and Boundary Element Hybrid (SIBEH) method, supported by experimental observations, has been developed to model crack growth in brittle composite systems. The surface integral method models fractures as a piece-wise continuous distribution of displacement discontinuities. When combined with traditional boundary element methods, the technique provides an efficient tool for modeling three-dimensional crack growth. This approach has been used to model matrix crack initiation in a lithium alumino-silicate (LAS) glass, ceramic that has been reinforced with continuous silicon carbide fibers. By modeling the effects of crack pinning and bridging, interfacial debonding, and frictional interface slip, this investigation aims to determine the stresses required for matrix crack initiation and the material parameters which promote graceful' failure modes. These results have been compared to existing analytical solutions for small crack growth.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1994
- Accession Number
- ADA342828
Entities
People
- Forrest T. Patterson
Organizations
- Massachusetts Institute of Technology