The optimization loop is working, but the results show that:

1. ✅ Parameter updates are happening in Bracket.prt
2. ✅ NX solver is running successfully  
3. ✅ Results are being extracted from .op2 files
4. ✅ Optimization loop completes
5. ❌ BUT: All trials return the SAME stress/displacement values

This indicates that the bracket geometry is NOT actually changing when we update
the tip_thickness and support_angle parameters. 

The issue is that these expressions exist in Bracket.prt, but they may not be
linked to any geometric features (sketches, extrudes, etc.) that define the 
actual bracket shape.

To fix this, the Bracket.prt file needs to be set up so that:
- The 'tip_thickness' expression controls an actual dimension
- The 'support_angle' expression controls an actual angle
- These dimensions are used in sketches/features to define the geometry

Without this, changing the expressions has no effect on the mesh or the analysis results.