Characterization of Compressive Damage Mechanisms in Ceramic and Polymeric Matrix Composite Materials.
Abstract
Experiments involving expansion of the dynamic strain rate capabilities of the split Hopkinson pressure bar were performed. Unusually high strain rate hardening was obtained for the compressive failure of silicon nitride, while for silicon carbide, failure followed a lower rate of hardening, crack kinetics criterion. The silicon nitride results were interpreted in terms of plastic deformation, which changed the mode of failure from that observed at low strain rates, and altered the strength-strain rate dependency, apparently through the influence of dislocation generation upon microcrack nucleation. Recent experiments involved the response of monolithic ceramics and fiber-reinforced ceramic matrix composites to dynamic loading under hydrostatic confinement. Curious results were obtained for monolithic ceramics, which appeared to derive from crack initiation/growth kinetics and the stability of confined microcrack ensembles. Composites under confinement were found to reflect both dilatational and shear aspects of damage development, which are primarily a function of the matrix phase, while the effect of the fibers was to alter the relative kinetics and, under certain circumstances, the sequence of events involved in the macroscale growth of damage through the eventual zone of failure. Considerable effort has been devoted to new approaches to capturing the critical events associated with compressive kink band nucleation and development in polymeric matrix, fiber reinforced composites. jg
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1995
- Accession Number
- ADA293171
Entities
People
- James Lankford Jr.
Organizations
- Southwest Research Institute