The montage with both bearings was considered in the same manner as the montage between the shaft and bearings. In the case of the attach on the frame there were two possibilities: the first one was to be considered the screws as 3D components and the second one was to consider nodes pairs placed in the same place as the screws. In both cases it is necessary to be written constrain equations on all three-space directions.
Considering a 3D screw model involve both a supplementary work and a finite element model growing without essential differences from the modal analysis point of view. Thus this approach was eliminated and the second one was considered. For a better model on frame and fore and back cases were considered circles with the radius equal with the screws radius.
On these circles there were defined pairs of nodes (frame fore case and frame back case) and there were defined