So I found the following question, and the top answer here seems to confirm that there is no location specific damage in Skyrim (so no benefit to headshots for instance):
Unfortunately the answers in that question did not address how armour affects the damage calculation. The top answer that did some location-specific damage testing, but did not appear to do any armour-based testing.
My follow-on question is whether armour protection is location specific or cumulative. For example, say I have armour on my chest, feet and hands at 50 points each, but I'm wearing no helmet – does my head benefit from 150 armour, or zero armour?
To put it another way: If I wanted to play a character who doesn't wear a helmet, does that put me at a major disadvantage (because any headshots would effectively be against an unarmoured target) or a minor disadvantage (because my cumulative armour total is slightly less)?
Best Answer
Skyrim's armor rating is simply flat damage reduction. It also has no location damage. There are no such things as "head shots".
On top of the listed armor rating, each armor piece (head, hands, chest, leg, shield) has a hidden armor value of 25.
Damage reduction also has a cap of 80% reduction, at around 500-600 armor rating. Anything over 667 guarantees maximum damage reduction.
More details at the UESP website