Explosive Forming of Tungsten Alloy Fragments

摘要

The efficacy of a number of internal notching systems and aluminium liners incontrolling the breakup of tungsten, 3.5%Ni, 1.5%Fe alloy cylinders filled with Composition B explosive has been investigated. Notching systems assessed include orthogonal, transverse and diamond patterns having notch depths ranging from 5 to 20% of cylinder wall thickness. Both slots and vee notches are examined. The aluminium liners were inserted inside the tungsten cylinders and had full wall thickness transverse slots machined at various intervals which were designed to induce shock wave interactions resulting in fractures beneath the slots. In all tests, the intent was to increase the yield of fragments with masses greater than lg for the attack of materiel targets. The internal notching grids with depths up to 20 % of cylinder wall thickness were unsuccessful in achieving high yields of fragments with masses greater than lg. The low dynamic toughness of the alloy resulted in the initiation and propagation of many tensile fractures between both slots and vee notches. Considerable through-wall breakup also resulted from the intersection of either tensile or shear fractures. Aluminium liner systems were much more successful in controlling cylinder breakup, with in in the number of fragments with masses greater than lg of up to 300%. The presence of slots between the aluminium liners resulted in shallow indentations in the inner cylindrical surfaces which were successful in controlling fracture paths probably due to a combination of the higher bending stresses induced and the interaction of shock waves propagating into the cylinder walls from the aluminium segments on both sides of the slots.