B. Shen et O. Stephansson, MODIFICATION OF THE G-CRITERION FOR CRACK-PROPAGATION SUBJECTED TO COMPRESSION, Engineering fracture mechanics, 47(2), 1994, pp. 177-189
Brittle materials subjected to compression can fail and the resulting
cracks can propagate in mode I and mode II in two dimensions. The maxi
mum strain energy release rate criterion (G-criterion) is examined for
its capacity of predicting the mixed mode crack propagation. When thi
s criterion is applied to an inclined crack subjected to compression,
it predicts the shear failure but not the tensile failure. The reason
for this phenomenon is discussed and a new form of this criterion, nam
ely the F-criterion, is proposed. The F-criterion uses the sum of norm
alized G(I) and G(II) (F = G(I)/G(Ic) + G(II)/G(IIc)) as the factor wh
ich represents the crack propagation and its direction. Implemented in
to the numerical displacement discontinuity method (DDM), the F-criter
ion can predict both mode I and mode II propagation of a crack system.
The capacity of the F-criterion in predicting both mode I and mode II
propagation is demonstrated for two models subjected to uniaxial comp
ression for a single crack and a set of two cracks. The numerical simu
lations show good agreement with the results of laboratory experiments
conducted on rocks and gypsum.