The Armor Piercing simulation we’re using punches real holes into the object at the exact location where the projectile hits.
Therefore we take the velocity of the projectile and it’s mass to compute it’s impact energy. Then we take the armor thickness and the projectiles impact angle and determine if it could breakthrough, get stuck, or would just graze off/ricochet.
That way it’s also possible to simulate multiple breakthroughs in a row, i.e. 2 or more plates of armor, or multiple decks.