I performed a static stress on an entire assembly with a load in the simulation.  I then added a motion analysis and added an equivalent load to the same areas with motion, but the Von Mises stresses I got were much lower than the static simulation, which didn't make sense to me.  So I removed the motor in the motion analysis and ran it again, but I did not come up with the same Von Mises stresses as the static stress simulation.  I have a feeling that I'm missing something, but can someone explain the difference and what kind of assumptions the two make?  I've been looking all over the place for a solution, but can't find it.