Asymptotic fields at the transition zone of a propagating interface crack

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The presence of conjugate square-root singularities in the stresses and particle velocities at the leading and trailing edges of the transition zone implies energy fluxes at these propagating edges. Since the principal failure of the interface bond is at the leading edge, one might ignore the energy flux at the trailing edge. At the leading edge energy is lost. This loss is necessary for propagation of the edge. Conceptually the loss of energy can be employed in a balance of rates of energies to construct a criterion for propagation of an interface flaw with a transition zone. The fluxes of energies into the leading edges, which are denoted by F and ~, associated with each case can be easily computed using Eq.(2.26) of \[5\]. The dependence of the energy release rate on the velocity c cannot be determined since the coefficients D2 and B 2 depend on c. However, it can be shown that ~ vanishes at the characteristic speed of the waves discussed by Achenbach-Epstein \[67, while F vanishes at a dual speed. Acknowledgement: The work reported here was carried out in the course of research sponsored by the U.S. Army Office Durham under Grant DAH CO4 75-G-0200.