7 Replies Latest reply on Jan 22, 2018 2:47 PM by Mike Pogue

    Modeling thermal path through screw

    Addison Mauldin

      Hi guys

       

      I am trying to figure out how to model the heat path through a screw head and into the bodies that the screw is joining together, mainly being a conduction heat transfer problem.  My problem is that when I use the toolbox 100 deg screw, simulation obviously says there is interference between the screw and the body it goes into.  I tried modeling the screw with it turned down to the minor diameter to fit the hole diameter but I don't know if that is the best way to go about it.  Any suggestions?

       

      Thanks

        • Re: Modeling thermal path through screw
          Mike Pogue

          The heat transfer is a function of a lot of things, especially the torque. Bolt heat transfer values are usually empirical--modeling dos not necessarily give accurate results.

           

          The way I do it is with this spreadsheet. It is based on a document developed in the sixties by Norden aircraft company. If you enter the information in green, you get the information in blue. This includes the apparent diameter and the  K*m^2/W.  I model the apparent diameter with split lines and apply the k*m^2/W as a contact resistance. This is very computationally efficient, because you can just suppress all of the screws. In my experience this method is accurate.

           

          This spreadsheet also gives you a back of the envelope estimate of how many screws you might need to get the heat out.