2 Replies Latest reply on Feb 18, 2012 8:27 AM by Alessandro Tornincasa

    Analysis with Shrink fit and very small interference

    Alessandro Tornincasa

      Hi,

      I would like to determine stiffness of a bearing by performing FEM analysis.

       

      Here is the model:

       

      1 - model.jpg

       

      I'm studying the model on only a slice.

      Boundary condtions are:

      - one fixed face

      - one axial force

      - no penetration contact conditions everywhere

      - shrink fit contact condition on the faces that are highlighted on the next image

      2 - Boundary conditions A.jpg

      Bolt connections on two holes:

      3 - Boundary conditions B.jpg

       

      The interference on the faces where shrink fit contact condition has been put is really low. Here is an esitimate of the diameters:

      4 - Interference A.jpg

      5 - Interference B.jpg

      One radius is 54.9515 mm and the other is 54.950.

      The interference is therefore 0.0015 mm .

       

      SolidWorks help file states that the shrink fit contact condition is ok to use only if interference is 0,1 % of the bigger diameter.

       

      In this case we have:

      0.0015/(54.9515*2) = 1.364e-5 = 0.0013 %

       

      Infact, if you look at the deformed shape (in attach is the video) it looks like the interferering component is applying a too high force to prevent interference.

       

      What should be done in this case:

      - Should you just remove interference and use a no penetration contact condition ?

      - Is this "high interference force" due to the fact that the mesh is too coarse ?

      - Should I use a very fine mesh (maybe as big as the intereference (0,0015 mm) ?

       

      I'm unsure about what I should do because there are very smal displacements and maybe even the preload due to the shrink fit contact could play some role.

       

      Thanks,

       

      Alex