A note on the geometric scaling of long-rod penetration

On the role of material properties in the terminal ballistics of long rods

“…related to the size of rod diameter compared with the size of the plastic zone at the crack tip of the rod material. This observation can explain the difference in the scaling behavior of copper and tungsten alloy rods (as explained in [19]). …”

“…The larger rod was more sharpened, resulting in a better penetration efficiency. Moreover, we found that for copper rods penetrating thick steel targets the geometric scaling is maintained [19]. Thus, changing the scale by a factor of 2, for these rods, resulted in a change of factor 2 in their respective penetration depths.…”

“…In [19], we found that indeed the nose shape of WA rods does not scale when two rods (a factor of 2 in size) are compared. The larger rod was more sharpened, resulting in a better penetration efficiency.…”

A Review of Similitude Methods for Structural Engineering

“…An application of scaled models to terminal ballistics is discussed in Rosenberg et al [104]. This investigation is motivated by the previous works focused on geometric scaling issues and nonscaling effects in this field.…”

“…Rosenberg et al [104] share the goals of Magness and Farrand [107] but their assumption is that size effects depend on the properties of the penetrator, not on those of the target. More precisely, the lack of geometric scalability is due to the failure mode: geometric scaling should hold for ductile penetrators, like copper, while semibrittle penetrators, made of WA or depleted uranium, may perform better at full scale because of their different mode of failure.…”