PHENOMENOLOGICAL MODELING OF A BRITTLE-TO-DUCTILE TRANSITION FOR BODIES WITH CRACKS

This paper considers the problems of construction of statically possib le stress fields in the vicinity of the crack tip. The authors suggest a mechanism for the generation of stresses parallel to the crack fron t and sufficient (according to the Tresca theory) for quasi-brittle st ress distribution in the planes perpendicular to the crack front. The requirement has been obtained for the body thickness, which would ensu re stress state triaxiality, that correlates with the empirical plane strain condition. The authors also propose the development of the mode l to take into account the effect of the material hardening and nomina l stresses. Critical stresses at a characteristic distance from the cr ack tip have been chosen as a brittle fracture criterion. On the basis of the Ludwik-Yoffe scheme and considering the models proposed, the a uthors constructed temperature dependences of the maximum stress inten sity factors.