Spherical Wave Measurement

SPHERICAL WAVE MEASUREMENTS IN LIMESTONE BLOCKS

Experiments were performed at Area 2 of the remote test site with 100-gram spherical explosive charges embedded in 1.2-m-diameter blocks of fine-grained limestone. The blocks were assembled in two halves stacked one atop the other, each with a mating ground flat surface and hemispherical cavity for the charge. Radial material velocity was measured with 17 circular wire loop particle velocity gages glued into machined circular concentric grooves at 17-mm spacing. The velocity gages were powered by a solenoid surrounding the entire specimen; each gage generated a voltage proportional to its radial velocity, its circumference, and the strength of the solenoid's magnetic field. Excellent consistency among measurements and excellent repeatability among three experiments provided confidence for using the data for strain-rate-dependent material model development.