Abstract
A correlation between the low energy dislocation substructures formed around the crack tip and the stress field variation is obtained. It has been shown that for small yielding, the dislocation substructure follows the surfaces along which the stress levels remain constant. On the other hand, when the region ahead of the crack tip undergoes large scale yielding, the modification of the spatial variation of the crack tip stress field through the work hardening by plastic deformation becomes important. The low energy configuration of cell structure observed in the plastic zone is predicted to follow the surfaces where the shear stress or the rotational stress component remains constant. These results follow from the variation of cell size, i.e., its inverse relationship to the component of stress.
Résumé
On établit une corrélation entre les sous-configurations de dislocations à basse énergie qui se forment autour de l'extrémité d'une fissure et la variation du champ de contraintes. On a pu montrer que, pour de faibles écoulements plastiques, la structure des dislocations se déploie sur les surfaces le long desquelles le niveau des contraintes demeure constant.
D'autre part, lorsque la région en avant de l'extrémité de la fissure subit un écoulement plastique à grande échelle, la modification qui frappe la variation spaciale du champ de contraintes à l'extrémité de la fissure du fait de l'écrouissage associé à la déformation plastique, devient importante.
On prédit que la configuration cellulaire à basse énergie observée pour la structure dans la zone plastique suit les surfaces correspondant à une composante constante de la contrainte de cisaillement ou de la contrainte rotationnelle.
Ces résultats sont déduits de la variation de la dimension de cellule, à savoir la relation inverse qui la lie à la composante de la contrainte.
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Jagannadham, K., Wilsdorf, H. Spatially varying crack tip stress fields and low energy dislocation substructures. Int J Fract 34, 297–307 (1987). https://doi.org/10.1007/BF00013084
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DOI: https://doi.org/10.1007/BF00013084