I am a new user in this forum. In free- free modal analysing, there is 6 rigid body motion (3 displacements and 3 rotations) with frequencie's of 0, but in my analysis there is 3 rigid body motions with frequencie's of 0 (linear displaements) and the frequencie's of others (rotational rigid body motons) are not zero. I do not know this reason. Please help me. I am analysing the model using Ansys 13.