Ansys 11 - Firtree Optimization

[dans11]

I am using Ansys 11 to optimize the design of a firtree attachment for a turbine blade similar to one seen here:

http://www2.tech.purdue.edu/at/courses/aeml/powerplantimages/2blademounts.jpg

I need to design the attachment to limit the equivalent stresses while minimizing the cross-sectional area.

I am relatively new to Ansys. So far, I have modeled the geometry using Workbench, since the complex geometry would be difficult to do in Classic. However, I am unable to import this geometry and parameters into Classic in order to use the optimization tool. Any tips on how to approach this differently?

Thanks for you help!