Response to: Comment on “Rigid and eroding projectile penetration into concrete targets based on an extended cavity expansion model” by Kong et al. Int. J. Impact Eng. 2017 by Z. Rosenberg et al

Kong et al comment on Rosenberg et al 's study, "Rigid and eroding projectile penetration into concrete targets based on an extended cavity expansion model." They present two viewpoints and show that Rosenberg et al's arguments are suspicious. First, resisting stress on a rigid projectile and deceleration of the projectile are velocity dependent, and second, resisting stress is actually dependent on shear failure surface and the equation rate rather than the single static unconfined strength of concrete, since the concrete material surrounding the projectile is subjected to triaxial stress state where volume change also occurs. Concrete is a nonhomogeneous composite material that is made up of coarse aggregate, mortar and interfacial transition zone. The dynamic behavior of concrete is dependent on the mix ratio, the size, strength and shape of coarse aggregate, porosity and so on. The dynamic behavior of concrete that is crucial for the penetration resistance may be far different even though the static compressive strength is identical.