Characterization of Mechanical Damage Mechanisms in Ceramic and Polymeric Matrix Composite Materials
Abstract
The principal objective of the program has been to establish the loading rate dependence of compressive deformation and fracture mechanisms in whisker and fiber-reinforced ceramic matrix composites, and in fiber-reinforced polymeric matrix composites. Work during the last year has emphasized several types of composite: Silicon Carbide fiber and Silicon Carbide whisker-reinforced pyroceram, and graphite fiber-reinforced thermoplastic. The behavior of a unidirectional carbon fiber-reinforced thermoplastic matrix composite subject to compressive loading at strain rates ranging from 10 to the minus 5 sec t the minus 1 to 5000 sec to the minus 1 is reported. Damage mechanisms are identified, and discussed in terms of matrix microstructure and fiber interactions. In particular, it is found that under quasi-static conditions, two absolutely critical factors control the life of the composite, i.e., the ability of the polymeric matrix to resist shear and thereby inhibit fiber flexure, and the ability of individual fibers to resist the nucleation of compressive plastic shear bands during flexure. It also is shown that at very high rates of strain (approx. 5000s to the minus 1), the strength suddenly begins to increase with strain rate in an extremely robust fashion. The measured strength-strain rate dependence in this range is shown to be consistent with the kinetics of kink band propagation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1990
- Accession Number
- ADA230220
Entities
People
- Herve Couque
- James Lankford
Organizations
- Southwest Research Institute