Recent advances in microprojectile impact tests have opened a new route to explore the behaviors of nanomaterials under extreme dynamic conditions. For example, impact tests have revealed that the specific penetration energies of ultrathin polymer films are remarkably high compared to the energies of conventional protective materials. The current experimental techniques are, however, unable to elucidate some of the complex atomistic mechanisms associated with the penetration process, which can only be realized through atomistic simulations.