Molecular dynamics simulation of ultrashort laser induced back-surface spallationin metallic fil m*

Using molecular dynamics methods combined withtwo-step radiation heating model,a completemicroscopic description of the dynamic progresses involved in laser induced back-surface spallation in metallicfil min stress confinement regi me is provided.Different fromthe front-surface ejection with strongly affectedmechanical stability of the front-surface by laser heating,the back-surface spallation is a disintegration of coldmaterial.The mechanismof spallationis analyzed as a result of theinteraction of the unloading wave and reflec-ted stress wave.The propagation of laser-induced stress wave is also further investigated,and the influences offil mthickness on spall thickness as well as the ti me when spallation begins are predicted.