3 Replies Latest reply on Oct 8, 2017 1:37 PM by Jim Wilkinson

    Polar moment of inertia of an area

    Jan Van Leeuwen

      When doing section properties one of the calculcated properties is the Polar moment of inertia of the section area, at the centroid.

      Polar moment of inertia is a measure of a beam's ability to resist torsion.

       

      Today I discovered that the calculation which SW uses, requires the beam's cross section to be circular.

      So a shaft or a pipe is OK, but any other shape will show incorrect values.

      (the other properties in the section property report screen may be OK though.

       

      In the Help files I can't find anything about this. Therefore I suggest that either a remark should be made in the section screen that the cross sectional shape should be circular or the calculation method for non-circular shapes and channel shapes (which are weak against twist) should be altered.

       

      If needed I can send examples.

       

      Regards,

      Jan