I got all my info from the
tests I did in the SE4 simulator.
Basically, SE4 picks a component to hurt. If the weapon type skips armor, internals will be hit before armor. Otherwise, if there are undamaged armor components on the ship, the internals cannot be picked. If the component has fewer hitpoints (kT of structure) than the damage inflicted, the component is destroyed. Any excess damage not required to destroy the component gets carried over to the next randomly chosen component.
If the component has sufficient hitpoints to survive the damage, then it is unaffected. The damage taken by the component is saved as "extra damage" which will be
added to the next hit taken
For internals, there is a pointer to the component that was hit Last, so every subsequent hit will damage that component until it is destroyed.
For armor, the next component to be hit is chosen randomly each time.
If shields regenerate between hits, they can possibly absorb not only the weapon damage but the extra damage as well, effectively healing "partially damaged" internals at the expense of shield strength.
When shields absorb a hit they will likely reset the internal damage pointer to a randomly chosen component.
SE4 has an odd method for choosing which armor component to hit. It is apparently inversely proportional to the hitpoints of the armor component. SE4 will choose weaker armor components more often, but not exclusively. Sometimes a tough armor will be chosen over a weaker armor.
This effect is amplified by the fact that strong armor pieces can usually survive the first damage, and SE4 chooses a new armor for the second hit. The new damage plus the "extra damage" can then destroy one or two weak armor components, leaving the tough armor untouched.
Any questions?