Ball bearing sim using combi214 not constrained enough

joestabilejoestabile WorcesterMember

When I use a bearing to ground connection in workbench, the shaft I am supporting with the bearing appears to be not constrained. Not sure what I am missing in the scoping.

Comments

  • peteroznewmanpeteroznewman Member
    edited September 2018

    Hi Joe,

    Here are the constraints you have in Static Structural currently:

    What is missing is a rotational constraint on the shaft.  You also have a frictionless support on two flat faces at the bearings. Those create a zero Y and Z rotation constraint on the shaft at those faces. I recommend removing that so that the force on the flat of the shaft can create a bend along the length of the shaft where the two bearings support the shaft.

    Delete one of the moments, and If you want a total of 200 N.mm of torque on the shaft, change that at the far end.  Replace the Frictionless support with a Remote Displacement that fixes Rotation about X and Displacement along X, while all others are free.

    Now the model will solve, but you will find the bearing stiffness is much too low as these forces cause large deflections.

    Add a zero to both Bearing Stiffness K11 and K22 values and solve to get a more reasonable deflection.

    Regards,

    Peter

    ANSYS 19.1 archive attached.

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