The PELE effect was used to design a projectile to disperse fragments against concrete targets. The shell was tungsten, and drivers were an energetic polymer, polycarbonate, and a thermite. In order to initiate the effect before impact, alumina anvil blocks were included in the projectile. The effect was activated by penetration through a concrete block. In order to easily visualize the radial dispersion of fragments, the target was only slightly wider than the projectile diameter. Radial dispersion of fragments after impact was measured by flash x-rays and by a witness plate. Impact velocities were 2.2 km/s. Observed radial fragment velocities were up to 900 m/s. The anvil blocks favorably affected the projectile fragmentation. Most tests produced a focused ring of fragments at about 10 degrees. The experiments were modeled with AUTODYN 2-D with a scheme to convert the results to 3-D fragment distributions. Three distinct mechanisms were found to launch the fragments. The calculations were in qualitative agreement with the witness block data. Moreover, the calculations indicated that most fragments were not captured by the witness block.

A comparison of techniques for obtaining projectile velocity history on a two-stage launcher and discuss gun code accuracy vis-a-vis pressure gauges and the new photonic Doppler velocimetry (PDV) technique is presented. The PDV technique itself is described in a companion paper. The PDV records were differentiated to compute acceleration and, hence, base pressure. Two acceleration episodes are revealed in the data. Base pressure values were compared with measurements from stationary pressure gauges and with predictions of a standard two-stage gun code. The agreement with the pressure gages was satisfactory. Code predictions did not account for the two acceleration stages. However, for the main acceleration episode, the predicted base pressure is in good agreement with the smoothed pressure computed from the PDV record. Both the gauge records and PDV contain short-time pressure spikes which are apparently real. Therefore, use of computed base pressure for projectile design may lead to failures if the projectile is vulnerable to pressure spikes.

Tungsten projectiles were shot into sand at velocities between 600 and 2200 m/s. Penetration was maximum at about 775 m/s. Below that velocity, projectiles were apparently stabilized by a fin set. Above that velocity, projectiles were broken by transverse loads. High‐speed penetration resulted in comminution of sand particles, reducing their size by about 1000 times.

Experiments have been conducted with 6.25 mm diameter tungsten rods striking concrete at 2.2 km/s. Three concretes were used-one was 2.35 g/cm(3) and the other two were 2.27 g/cm(3). The erosion rates were measured to be T/Delta L=2.4-3.1 depending on the density of the concrete. This is greater than the hydrodynamic value, which shows that the strength of the penetrator is affecting the penetration. The cratering efficiency was computed (which included surface spall) and was found to be commensurate with the strength of the concrete, 28-34 MPa. CTH calculations were conducted using the brittle fracture kinetics (BFK) and Holmquist-Johnson-Cook (HJC) material models for concrete. Density in the calculations was 2.25 g/cm(3). It was not possible to match erosion rates at 2.2 km/s, which were too high in the calculations. Also, computed crater volumes were much too small, mainly due to spall in the experiments that was not shown in the computations. Another significant inaccuracy of the calculations was the damage extent, which became unrealistically widespread as time increased in the BFK model. (C) 2008 Elsevier Ltd. All rights reserved.