Temporary cavity created by free-flying projectiles propelled from a powder-actuated nail gun

Abstract

Nails and driving pins discharged from powder-actuated fastening tools bear some special ballistic characteristics. Compared to the usual pistol or revolver projectiles, the sectional density (S) of fastening pins is extremely high. The general prevailing opinion is that the kinetic energy delivered by fastening tools is not high enough to cause a temporary cavity. Therefore, it was the aim of this study to investigate the wound morphology due to fastening bolts discharged from a powder-actuated direct-acting nail gun (where, in contrast to modern piston-type tools, the expanding gases act directly on the fastener) using ballistic soap blocks as simulants. For test shots, a direct-acting powder-actuated nail gun which features three interchangeable barrels (caliber (cal.) 6, 8, and 10 mm) was used. The average kinetic energy was 537, 532, and 694 J for the 6-, 8-, and 10-mm cal. bolts, respectively. Test shots on the ballistic soap blocks demonstrated that free-flying projectiles discharged from direct-acting fastening tools are able to create a temporary cavity.

Modeling of temporary cavity in ballistic gelatin based on spherical cavity expansion model

“…1,2 The expansion of the temporary cavity involves large deformation and failure of the targets, which is a major factor in assessing the ballistic trauma. Some previous research works have studied the factors influencing the size of the temporary cavity, [3][4][5] and it is generally accepted that the expansion of penetration cavity is caused by energy transfer of the penetrator to the target medium. The medium surrounding the penetrator tract are driven outwards from the penetration path in a radial direction, see Figure 1, in which the penetrator is a high-speed bullet.…”