why can’t kevlar stop rifle bullets even though it’s strong than steel on an equal weight basis?

Question

Ar500 steel plate can stop rifle bullets. In my brain I’m thinking like “well if kevlar is stronger than steel, then slab of kevlar of the same size of an ar500 plate should stop rifle bullets too”. Clearly it doesn’t and I don’t understand why

In: Engineering

Answer 1

Even steel struggles with rifle rounds sometimes. Rifle rounds generally travel much faster than pistol rounds and are smaller in diameter. The combination of speed and small area create a tremendous amount of energy concentrated in a very small area. Pistol bullets get caught by the layers of Kevlar like a tightly woven net, rifle bullets tend to divide some fibers of Kevlar and tear the ones that they can’t divide.

Pica of what a rifle round can do to AR500. This was a 22-250 that was firing at around 4350fps. Target was 60ish yards out.

22-250 vs AR500 3/8 Gong