Strain field formation in plastic bonded explosives under compressional punch loading

An inert simulant for one type of explosive formulation was subjected to lo w rate compressional punch deformation to determine the presence of potenti al strain initiation mechanisms. The presence of certain types of strain in itiation mechanisms may lead to unintentional ignition in some explosive fo rmulations. Laser induced fluorescence speckle photography was used to dete rmine the magnitude and direction of the developing strain field during tes ting. Post-test SEM analyses was used to determine damage mechanisms occurr ing within the material. The magnitude and direction of the plastic flow li nes show that a dead zone forms in the strain field immediately under the p unch in agreement with Prandtl's slip-line solution of the punch problem. H owever, material flow patterns diverge from Prandtl's solution for other re gions. Large shear strains also occur in the specimen, leading to the forma tion of slip bands in the hard phase constituent. (C) 2001 Kluwer Academic Publishers.