John Doyle
Ansys Employee

I think this can be done.  Please refer to Workbench User's Guide=> Working with Parameters=> Expressions, Functions, Quantities, and Units...

Why do you have to set b=zero?  Won't that just cause problems during geometry creation (i.e. how do you build a gusset with zero thickness)?  Wouldn't it be better to just skip building gussets whenever a= zero?