Strain field formation in plastic bonded explosives under compressional punch loading

An inert simulant for one type of explosive formulation was subjected to low rate compressional punch deformation to determine the presence of potential strain initiation mechanisms. The presence of certain types of strain initiation mechanisms may lead to unintentional ignition in some explosive formulations. Laser induced fluorescence speckle photography was used to determine the magnitude and direction of the developing strain field during testing. Post-test SEM analyses was used to determine damage mechanisms occurring within the material. The magnitude and direction of the plastic flow lines show that a dead zone forms in the strain field immediately under the punch in agreement with Prandtl's slip-line solution of the punch problem. However, material flow patterns diverge from Prandtl's solution for other regions. Large shear strains also occur in the specimen, leading to the formation of slip bands in the hard phase constituent. (C) 2001 Kluwer Academic Publishers.