Modelling microstructurally sensitive fatigue short crack growth
Abstract
Microstructurally sensitive fatigue short crack growth can occur in many engineering components devoid of large defects. Continuum mechanics principles, including linear elastic fracture mechanics, used in damage tolerance design and life prediction methods are not applicable in these situations and therefore new concepts need to be developed to characterize this type of growth. A microstructurally sensitive model of fatigue crack growth is presented in which the effect of microstructure is dominant in the early stage of growth but plays a negligible role after the crack has gone through the transition from structure-sensitive to structure-insensitive growth. The effect of both microstructure and structure sensitive variables on the transition from short cracks to continuum mechanics and the conditions for crack instability leading to final failure are examined. The microstructural variables incorporated in the equations that describe the model are those controlling the extent and intensity of crack tip plasticity such as grain size, precipitation and dispersion hardening, strain hardening and mis-orientation between grains. It is expected that the concepts developed within the model will form the basis for the design of new crack-resistant materials.
- Publication:
-
Proceedings of the Royal Society of London Series A
- Pub Date:
- October 1994
- DOI:
- 10.1098/rspa.1994.0131
- Bibcode:
- 1994RSPSA.447..111D
- Keywords:
-
- Continuum Mechanics;
- Crack Propagation;
- Elastic Properties;
- Fracture Mechanics;
- Microstructure;
- Short Cracks;
- Crack Tips;
- Failure;
- Grain Size;
- Mathematical Models;
- Precipitation Hardening;
- Strain Hardening;
- Structural Mechanics