Extension resistance of a semi-infinite crack in a viscoelastic strip

Crack tip stress field in a viscoelastic strip is complicated dependent not only on crack tip configuration, length and loading condition but also on the histories of crack extension and loading. Extension resistance of a semi-infinite crack traveling in a viscoelastic strip is investigated standing on precise evidences observed in experiments, in which crack extends with some constant velocities under several constant temperatures. Time variation of J'-integral in the process of crack propagation was evaluated. The results obtained are summarized that during crack propagation with a constant velocity J'-integral keeps a constant value, which is considered as one of the material characteristics dependent on temperature and crack velocity.