Molecular dynamics simulation of plastic deformation of pure titanium under shock loading

Laser shock peening utilizes the mechanical effect of shockwave to improve the mechanical properties of metal materials, however, it is very difficult to measure the dynamic physical parameters after shockwave, the local dynamic mechanical parameters, and the development of microstructure with current means of experiment. The molecular dynamics method is employed to conduct the shock simulation in pure titanium at a starting temperature of 300 K, the dynamic dual-wave structure feature of the shockwave in pure titanium under the shock loading is observed, and the change of the mechanical parameters as well as the dynamic growing process of twin phase under shock loading are obtained. During the plastic deformation, the stoppage and release of dislocation make the normal stress rise while the shear stress and von Mises stress continue to drop, and the parallel twin gratings are formed. A layer of amorphous structure is observed on the surface subject to shock loading, and its formation is related to ultrahigh strain rate plastic deformation and dynamic recrystallization behavior. Both the twin structure and the amorphous structure coincide with the results obtained by transmission electron microscopy.