One of the best open programs for Fea analysis is CalculiX. (calculix.de, calculixforwin.com ). Now it works thru the netgen mesher and step format. The problem that the step has units inside and the mesh should be translated with using units other than mm. The same problem appears with Elmer-FEM. It came from opencascade kernel but generally it is bot a big deal it you know about that.
Here are some exapmles of meshing STEP geometry in Netgen: http://youtu.be/ZYF2IBd3Fr0 My questions is what the next step in the integration with open-source FEA?