Elastic/Plastic Identation Damage in Ceramics. I. The Median/Radial Crack System. Part II. A Study of Kink Band Formation in Composites.
Abstract
A theory for describing the evolution of the median/radial crack system in the far field of sharp-indenter contacts is developed. Analysis is based on a model in which the complex elastic/plastic field beneath the indenter is resolved into elastic and residual components. The elastic component, being reversible, assumes a secondary role in the fracture process: although it does enhance downward (median) extension during the loading half-cycle, it suppresses surface (radial) extension to the extent that significant growth continues during unloading. The residual component accordingly provides the primary driving force for the crack configuration in the final stages of evolution, where the crack tends to near-half-penny geometry. On the hypothesis that the origin of the irreversible field lies in the accommodation of an expanding plastic hardness impression by the surrounding elastic matrix, the ensuing fracture mechanics relations for equilibrium crack growth are found to involve the ratio hardness-to-modulus as well as toughness. observations of crack evolution in soda-lime glass provide a suitable calibration of indentation coefficients in these relations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1979
- Accession Number
- ADA078839
Entities
People
- A. G. Evans
- B. R. Lawn
- C. H. Hseuh
- D. B. Marshall
Organizations
- University of California, Berkeley