General Mechanical

General Mechanical

Simulating slip in bolted joint

    • jonsoln
      Subscriber

      Hi!

      I want to calculate the maximum torque my bolted joint can hold before slipping, but I struggle to get good results from Ansys. I've done hand calculations, so I know what torque to expect, but I'm interested in checking the torque based on planar tolerances in Ansys. The geometry consists of a hub bolted to an impeller using pretensioned beam elements. The contact between the parts is frictional with a coefficient of 0,1. The contact face of the impeller is not level so the surfaces only touch near the center of the face. Large deflection is on.


    • Rev0
      Subscriber
      Hallo I would recommend you to go with method 2 (displacement/rotation controlled loading), because it will lead to converged results and you can just check the moment reactions. Contact sliding of the contact tool is not practical as you noticed.
      Probably the main problem ist the modelling technique of the bolts with beams. These introduce a stiffness as well, because they're connected to both parts.
      First you could replace them by a simple normal force in the area of the bolt heads. This is only a first guess but can be verified analytical.
      Second, replace the normal force by solid bolts. The heads should have frictional contact as well. In the first step pretension the bolts and lock them in the second step. This will lead to a higher moment reaction bacause of the additional friction surfaces.
      Regards JB
    • jonsoln
      Subscriber
      Thanks for the answer! I agree that replacing the beams with a force is better since the rotational stiffness is removed. I also had to increase the angular deformation quite a lot to reach the maximum torque.




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