Dynamic glass transition dramatically accelerates crack propagation in rubberlike solids

A crack propagating in a strained rubberlike solid exhibits an abrupt change of the propagation velocity by typically more than 10² times at a specific threshold strain energy, which is a phenomenon called the ``velocity jump.'' Despite its scientific and industrial significance, the mechanism of the velocity jump had been unsolved for more than 30 years. This paper gives a clear answer to the mechanism, showing dynamic glass transition at the crack tip is the true origin of the crack velocity jump. We present concerted investigations involving theoretical analysis, numerical calculation, and experiment to establish an integrated understanding of the mechanism. Our findings indicate that the velocity jump can be found in general viscoelastic materials.