Critical scales govern the mechanical fragmentation mechanisms of biomolecular assemblies

Fragmentation mechanisms of peptide assemblies under shock deformation are studied using molecular dynamics simulations and are found to depend strongly on the relative magnitude of the shock front radius to the fibril length and the ratio of the impact energy to the fibril cohesive energy. The competition between size scaling of curvature and impact energy leads to a mechanism change at a critical impact velocity, developing a stark contrast in the size scaling of fragmentation at low and high strain rates. We show that the fragmentation mechanisms can be classified on the basis of the length and time scales of deformation and relaxation to provide new insight into experimental observations.