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
“On equal weight basis” is the easiest answer to this. The Ar500 steel plate is ~8 pounds for less than a square foot. That’s heavier than most kevlar vests, which themselves cover more than a square foot.
The other part of this answer is that “five times stronger than steel” isn’t actually a meaningful statement. Kevlar has a very high *tensile* strength. That doesn’t mean it’s more resilient than steel for all applications.
Kevlar is woven, and ultimately there are much larger gaps in the material than the gaps between molecules in a steel plate. That’s why we use it, in fact. When Kevlar stops a bullet, it deforms and uses tensile strength to resist the bullet.
Steel doesn’t use tensile strength to stop bullets. It uses *Impact* strength.
TLDR The mechanics of how these materials stop bullets are very different and you’re not comparing apples to apples.
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