Inertia relief

[mikechy]

If in my model I have mass elements and want to use an inertia relief option, do I need to create gravity or centrifugal forces to analyse effect of mass forces, or 'inertia relief' will do it for me? If last one is correct, then what will be a direction of mass forces (in other words, what will be a direction of accelerations)?

Thanks in advance,
Fred