FE simulations require the use of a consistent system of units. In structural mechanics, the SI system and the system mm-t-s (millimeter-tonne-second) have proved their worth.
The table below (in German) provides a compilation of some consistent unit systems.
Checklist Simulation Tasks
The definition of a simulation task requires clarification of various points. The checklist, which you can download here (in German), gives you an initial overview.