Thanks for the suggestions: we found that we were missing the parasolid importing license. We now have a trial license and by saving the model as a parasolid, (Both Nastran and solidworks have parasolid kernels) and using the new function "midplane", our solids were easily meshed.
The only...
Importing a solidworks .prt generated iges file into nastran2001 seems to work for us but when we import .sldasm files, via iges, the geometry goes astray. I would be interested to hear from anyone who had the same problem and what , if any solution is available.