I confirm that I can generate Graphics3D objects with the first option. 
sim = SystemModelSimulate[
  "Modelica.Mechanics.MultiBody.Examples.Elementary.DoublePendulum"]
g3d = Table[sim["Graphics3D", t], {t, 0, 3, 1}]
However, I am stuck because I cannot export the Graphics3D objects. I have tried
dName = NotebookDirectory[];
Export[StringJoin[dName, "t1.lwo"], g3d[[1]]]
and got an error.
Graphics3D contains no data that can be exported to the LWO format.
I also tried 3ds, dxf, and dae and got the same error for the respective format.
After reading posts on various forums I have concluded that the Export[] does not support the Graphics3D object that comes out from the simulation. It seems that the problem is with the Translate part of the Graphics3D object. Here are some details of the StackTrace of the error.
Export["C:\\t1.lwo", 
 Graphics3D[{Translate[
    GeometricTransformation[{RGBColor[0., 0.494949494949495, 1.],
      Specularity[6., 40], ...
So is there a way to convert the Graphics3D object to something exportable? I have tried the solution here but it did not work.
Thank you,
B