Hello Tom,
The free Student license limits exporting the SpaceClaim document in a neutral format. The intention of providing free software is so students can learn to use the software. Obviously, if Ansys provided full functionality in the free software, few people would pay for a license.
Many universities have purchased a Research or Teaching license which has no such limitation. If you ask at your university, you may find a computer in a lab on campus that has that license installed. It is true that if you take your .scdoc file from the Student version, you can open it on that computer and export the neutral file.
If you are not a student, but running a business, then you could purchase a license for SpaceClaim from Ansys.
You are navigating away from the AIS Discovery experience