Not sure how much of this is already known, but I’ve been doing some experiments on attacking armor using the Emerald Nebula scenario and a modded beam laser, and I’ve learned a few things. First, direct damage has only a minimal effect on whether a shot does damage to armor - if a 1000 damage weapon has an armor penetration of 1, most armors should withstand it.
Secondly, it seems that to reliably damage armor, a weapon must have an armor penetration no more than 90 lower than the value of the armor it’s attacking - any lower than that, and it starts becoming reliant upon increasingly rare critical hits. —Update: Seems I was basing this part on the incorrect understanding that whether a shot penetrates armor is determined by the strength of the armor module it hits - it is actually determined by the “Average Armor” of the ship as a whole, which can be displayed by clicking on an icon in the upper-right hand corner of the ship view. Thus, to penetrate armor without crits, your armor penetration must be higher than the average armor of the ship.
I started researching this mainly due to the ready effectiveness of fighters in large numbers vs cruisers - from this data, it is clear that you need enough fighters to rapidly drop armor into the 100-range - once this occurs, the remaining armor should fall rapidly.
Anyway, hope this helped!