Is Damage taken impacted by durability of a piece of armor?

Solution 1:

Armour and Helmets will reduce damage done by the same amount regardless of how much durability it has.

I suspect this may be because when you are hit reduced damage is applied to the player, followed by durability being subtracted from the armour/helmet. Regardless, a armour/helmet of any level will protect you the same amount whether it has 1 point of durability or full durability.

When it comes to deciding whether or not to switch out for lower level but higher durability gear, you need to consider how many times you are likely to be shot. A full durability lvl 2 vest will prevent more damage than a lvl 3 vest with 10 durability if you are shot more than once.

You can find more about the mechanics of armour and helmets in this video:

Even though the video is from April, there isn't evidence that they have changed the mechanic in the recent patches.