Abstract
Fracture from a straight crack under mixed mode loading conditions and small scale of yielding is studied. It is assumed that crack growth occurs in either mode I or mode II. Comparison of theoretically obtained values of the mode I stress intensity factor at incipient kinking with experimental results indicates that mode I is preferred to mode II when the loading is such that the crack surfaces are traction-free, i.e. in the absence of a confining pressure. Mode II would be preferred only if the ratio K II c/K I c between the stress intensity factors is very low, between 0.38–0.81, depending on the load situation. Since there are reasons to believe that most materials are characterized by higher values of K II c/K I c, the conclusion is that mode II hardly occurs in the absence of a high confining pressure.
Résumé
On etudie la rupture entraînée par une fissure droite sujette à des sollicitations selon un mode mixte et comportant une plastification sur une petite échelle. On suppose que la croissance de la fissure se produit sous un mode I ou un mode II.
En comparant les valeurs théoriques du facteur d'intensité de contraintes selon le mode I correspondant à l'évasement initial et les résultats expérimentaux, il s'indique que le mode I est privilégié par rapport au mode II lorsque la sollicitation est telle que les surfaces de la fissure sont libres de toutes contraintes, c'est-à-dire en l'absence de toute pression de confinement.
Le mode II ne serait privilégié que si le rapport K II c/K I c des facteurs d'intensité de contraintes est très faible, à savoir entre 0,38 et 0,81, selon les conditions de sollicitation.
Comme il y a de bonnes raisons de croire que la plupart des matériaux sont caractérisés par des rapports K II c/K I c plus élevés, on en conclut que, en l'absence de hautes pressions de confinement, le mode II a peu de chances de se manifester.
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Melin, S. Fracture from a straight crack subjected to mixed mode loading. Int J Fract 32, 257–263 (1986). https://doi.org/10.1007/BF00018544
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DOI: https://doi.org/10.1007/BF00018544