By means of counter-evidence. it is proved that the original J integral doe
s not satisfy the conservation law for general heterogeneous media. In the
present paper, a modified version J* is re-proposed, which is a path-indepe
ndent integral. The modifier term is related to stress and strain discontin
uities occurring in material interfaces, and possibly occurring in interfac
es between elastic and plastic zones. The integral J* can be interpreted as
an expression of energy release rate. therefore, there exists an integral
fracture criterion correspondingly. With regard to computational aspects re
lated to finite element analysis, interface elements have been proposed to
deal with stress and strain discontinuities in the material interfaces. For
a generic case, adaptive analysis is recommended to take into account the
discontinuities in the material interfaces, and possible discontinuities in
the interfaces between elastic and plastic zones around a crack tip, in an
optimal manner. (C) 2000 Elsevier Science B.V. All rights reserved.