Dynamic crack propagation drives catastrophic solid failures. In many amorphous brittle
materials, sufficiently fast crack growth involves small-scale, high-frequency microcracking
damage localized near the crack tip. The ultrafast dynamics of microcrack nucleation,
growth, and coalescence is inaccessible experimentally and fast crack propagation was
therefore studied only as a macroscale average. Here, we overcome this limitation in
polymethylmethacrylate, the archetype of brittle amorphous materials: We reconstruct the …

Dynamic crack propagation drives catastrophic solid failures. In many amorphous brittle
materials, sufficiently fast crack growth involves small-scale, high-frequency microcracking
damage localized near the crack tip [1]. The ultra-fast dynamics of microcrack nucleation,
growth and coalescence is inaccessible experimentally and fast crack propagation was
therefore studied only as a macroscale average. We will see how to overcome this limitation
in polymethylmethacrylate, the archetype of brittle amorphous materials: We reconstructed …