Hi Bas - the mesh dialog will only show up when you're exporting to a mesh-based output format.

STEP and IGES are primarily NURBS based formats, and when MoI exports to either of these formats it writes out its NURBS surface data and does not create a mesh.

You will see the mesh options dialog if you export to OBJ, LWO, 3DS, FBX, or SKP formats - for those formats MoI will convert from NURBS surfaces into polygon mesh faceted data.

Finite Element Analysis may require some particular properties to how the mesh is constructed though, so you may need to export NURBS data to your FEA program and have the mesh created inside of that other program rather than doing a mesh export from MoI, for that particular purpose of using the mesh for FEA work.

- Michael