Armor is simply based off of material. If it's about as tough as human flesh, 1d6 armor. If it's about as tough as a tank, 3d10 armor. Thickness has nothing to do with it: just simply look at something and compare it to a tank, a nuclear bunker, or godforged adamantium forged in the fires of hell itself.
If you're going for a double-layer armor thing (example: dinosaur with 1d10 armor skin is wearing a suit of armor), you can add 1d6 to the total armor level. Keep in mind that it will help in general damage, but the armor only protects what it's actually covering (I.E: component damage on an exposed object doesn't get the 1d6 bonus).
And finally, please, please, please stop thinking that more armor is better. Maybe your 5d10 tanks are nigh invincible, but where's the fun if they can't explode into a fireball the size of an office building?
EDIT: TL;DR: NO