Sim Chips or Sim tickets are used (along with the Stamina that would normally be used) to quickly gain the rewards from a battle that has been completed before. To simulate a Campaign or Challenge battle, it is additionally required that you have once completed that battle before with 3 stars (i.e., won without suffering a single knockout), but resource missions do not have that requirement.
Experience is not awarded in any simulated battle, though Resource missions and Challenges don't directly give XP to the combatants or the account anyway, therefore its recommended to use Sim Chips for those.
If using a Sim Chip on a Heroic-difficulty battle or a Resource mission that has a daily victory limit of 3, one daily victory will still be consumed. Completing a battle with Sim Chips will count towards the three relevant daily objectives.
Challenges can be simulated after an update. 3-star completion (winning without a knockout) is counted even if you did it before the update.