The following are the only two solutions I know.
A)The first which is currently in practise:
Prerequisite: I-DEAS 9 minimum (I think)
Purchase Parasolid Translator Add-on for ANSYS
How:
In I-DEAS 9, under the file tab, there is an "Interoperate" function. This functions will translate Assemblies or Parts in the Library into ".xpk" files, or only Parts into parasolid ".x_t" files.
ANSYS only imports ".x_t" files, but with the parasolid translator add-on.
Feedback:
Generally, models which do not have complex surfaces will work fine. At least in my opinion has better curves and surfaces than IGES.
Imported models are in meters. So scaling is needed for those using millimeters as units.
B)I think this is possible:
Prerequisite: UG or NX upgrade (I think)
Purchase UG Translator Add-on for ANSYS
How:
Well, move into the NX platform or the UG NX and UG model files will be the key models which I think is ".prt".
Feedback:
Never used, just a suggestion for evaluation or trial from the software sales support.