In this work, crack initiation from a notch tip in elements subjected to a mixed mode
loading was studied. Two phenomenological criteria, based on a concept
of Leguillon, were proposed and applied to predict crack initiation from a
-notch
tip in a brittle or quasibrittle material. The first criterion, called in this paper the
-
criterion, makes use of the critical strain energy release rate and the ultimate tensile
stress as the main parameters of fracture. It requires calculations of strain energy
release rate after an infinitesimal crack kinking. By means of some numerical effort,
we established the indispensable relationships between the strain energy release rate
after crack kinking and the remote mixed mode loads. These relationships enabled us
to apply directly the proposed criterion to mixed-mode loaded notches. We also modified
the strain energy density criterion proposed by Sih on the basis of Leguillon’s
concept to form a criterion capable of predicting the crack initiation from a
-notch
tip. This criterion, which we call the
-
criterion, benefits from its simplicity in applications. Confrontation with experimental data
shows that both the criteria enable reasonably accurate prediction of fracture in elements
with
-notches
subjected to mixed mode loading. Consequently, they can be effectively applied in
practical engineering applications.
