Plastic Deformation from Shock or Impact

Initiation Due to Plastic Deformation From Shock or Impact 

Indian Head Division, Naval Surface Warfare Center, Indian Head, MD 20640 

The intent of this chapter is to identify and understand the mechanisms responsible for initiation of chemical reactions in crystalline explosives as they undergo shock or impact. Guidance for this effort has been obtained from the observations of shocked or impacted explosive crystals using the Atomic Force Microscope (AFM). The AFM has a spatial resolution of about 10 m which allows changes in the lattice or molecular structures of shocked or impacted crystals to be detected at the 

Section (1) of the Chapter briefly reviews the large data base that has been obtained from Atomic Force Microscopy of shocked or impacted crystalline solids. 

Much of this data has been or will be published elsewhere [5-10]. The data shows that the lattice and molecules of plastically deformed crystals experience significant and semi-permanent deformation. From this, insights are obtained that permit the development of an approximate deformed lattice potential for shocked or impacted crystals. Shear bands have been observed in shocked or impacted crystals. Some of shear bands show that molten material had been extruded from deep within the bands. These are possibly the source of the hot spots thought to be responsible for initiation during shock or impact. On the basis of these and other experimental observations it is concluded that energy dissipation and localization during plastic deformation is likely to be responsible for initiation of chemical reaction. 

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