I actually know very little offhand, but I've had the privilege of being on a website that was frequented by those who have done the primary work. Nathan Okun is acknowledged as the leading expert in the world on shell ballistics and the effects of explosions, as well as how armor works. Here is his explanation:
http://www.navweaps.com/index_tech/tech-026.htm
Follow the "Back To" link at the bottom of the page to find a gold mine of naval information, mostly written by the people who know.