High pressure shear band formation is a critical phenomenon in energetic materials due to its influence on both mechanical strength and mechanochemical activation.While shear banding is known to occur in a variety of ...High pressure shear band formation is a critical phenomenon in energetic materials due to its influence on both mechanical strength and mechanochemical activation.While shear banding is known to occur in a variety of these materials,the governing dynamics of the mechanisms are not well defined for molecular crystals.We conduct molecular dynamics simulations of shock wave induced shear band formation in the energetic material 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)to assess shear band nucleation processes.We find,that at high pressures,the initial formation sites for shear bands,“embryos”,form in excess and rapidly lower deviatoric stresses prior to shear band formation and growth.This results in the suppression of plastic deformation.A local cluster analysis is used to quantify and contrast this mechanism with a more typical shear banding seen at lower pressures.These results demonstrate a mechanism that is reversible in nature and that supersedes shear band formation at increased pressures.We anticipate that these results will have a broad impact on the modeling and development of high-strain rate application materials such as those for high explosives and hypersonic systems.展开更多
基金Funding for this project was provided by the Director’s Postdoctoral Fellowship program at Los Alamos National Laboratory,project LDRD 20220705PRD1Partial funding was provided by the Advanced Simulation and Computing Physics and Engineering Models project(ASC-PEM)+1 种基金supported by the U.S.Department of Energy(DOE)through LANL,which is operated by Triad National Security,LLC,for the National Nuclear Security Administration of the U.S.Department of Energy(Contract No.89233218CNA000001)Approved for Unlimited Release LA-UR-21177.
文摘High pressure shear band formation is a critical phenomenon in energetic materials due to its influence on both mechanical strength and mechanochemical activation.While shear banding is known to occur in a variety of these materials,the governing dynamics of the mechanisms are not well defined for molecular crystals.We conduct molecular dynamics simulations of shock wave induced shear band formation in the energetic material 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)to assess shear band nucleation processes.We find,that at high pressures,the initial formation sites for shear bands,“embryos”,form in excess and rapidly lower deviatoric stresses prior to shear band formation and growth.This results in the suppression of plastic deformation.A local cluster analysis is used to quantify and contrast this mechanism with a more typical shear banding seen at lower pressures.These results demonstrate a mechanism that is reversible in nature and that supersedes shear band formation at increased pressures.We anticipate that these results will have a broad impact on the modeling and development of high-strain rate application materials such as those for high explosives and hypersonic systems.
