抄録
This paper presents theoretical considerations on the expressions for the dynamic energy release rate in elastic crack propagation.
The validity of the expressions, which have been proposed by Erdogan, by Achenbach and by Freund, is discussed on the basis of the fundamental expression defined by an overall energy rate balance.
The energy release rate is divided into the usual quasi-static energy release rate plus a non-positive dynamic contribution; they are discussed as the strain energy release rate for the former and as the kinetic energy generating rate for the latter. They will be useful as new parameters related to the dynamical behavior of crack propagation.
The mathematical derivations given here are not in detail, but rather the background of the assumptions and physical considerations of the results are emphasized.
