Untitled - Sciencemadness Dot Org

DETONATION PROPERTIES
3.4 Plate Dent Test. The plate dent test was developed during World War II at
the Explosives Research Laboratory at Bruceton, Pennsylvania.2 It was designed to
provide a relative estimate of explosive power. The test involves detonating an un-
confined cylindrical charge of high explosive in contact with a heavy steel plate and
measuring the depth of the dent produced in the plate. The explosive charges are of
a diameter and length that ensure establishment of a steady-state detonation wave
of almost infinite-diameter velocity in most explosives. The steel witness plates are
massive and strong enough to limit the damage to the area of interest.
The explosive to be tested is prepared in the form of 1 5/8-in.-diam cylinders of
varying lengths (see Table 3.46). The test plates are 6-in.-square by 2-in.-thick
pieces of 1018 cold-rolled steel, cut from 2- by 6-in. bar stock having a Rockwell
hardness of B-74 to B-76.
To eliminate spalling from the rear surface, several test plates are stacked ver-
tically, and the upper surface of the top plate is greased lightly to ensure good
coupling with the charge. The test charge is centered on the plate, a booster of ade-
quate size is placed on the charge, and the detonator is put in place. If necessary, a
piece of tape may be used to hold the assembly together and maintain good contact
among its various components. The assembly ready for firing is shown in Fig. 3.02.
280
Fig. 3.02. Plate dent test assembly.