5 Replies Latest reply: Dec 7, 2012 11:13 AM by Phil Perlich

    How to constrain cylinder laterally in only one direction

    Phil Perlich

      I have a cylinderical face with the axis in the z direction. I want to allow the face move in the x direction, but not in the y or z directions. I know how to constrain the z direction, but I am stumped on how to do it in the y direction.

        • Re: How to constrain cylinder laterally in only one direction
          JOHN GEORGE

          Phil,

          Can you please post a picture

          It's very hard to understand what exactly you are looking for..

          • Re: How to constrain cylinder laterally in only one direction
            Anthony Botting

            You can use the "advanced fixtures" option, first (don't select the cylindrical face, first, because it will default to setting-up an R, theta, z restraint system). Select a plane perpendicular to Y. then set the displacement =0 in the 'Normal' direction to that plane. Now select the cylindrical face. You could set the same displacement =0 in one of the other two directions in the dialog, but you cannot tell which is which unless you attempt each one and observe the arrows on-screen.

              • Re: How to constrain cylinder laterally in only one direction
                Phil Perlich

                Anthony,

                 

                I tried what you suggested, which created a 'fixed hinge' fixture. This did not allow the axis of the cylinder to deflect in the x-direction as desired. I have attached a picture for reference. I want to restrain the axis in the y-direction, but leave it free in the x-direction.

                 

                As a work around, I placed a virtual wall at the top of the eye. This was acceptable since I am not focused on the stress in the eye.

                The deflection at the center of the spring is .127" with the fixed hinge.

                The deflection at the center of the spring is .588" with the virtual wall. (same load of course)

                 

                Capture.JPG

                  • Re: How to constrain cylinder laterally in only one direction
                    Anthony Botting

                    Hi Phil; yes, it does set up a fixed hinge if there is a cylindrical surface or axis selected for the reference. You have to "force" the software to allow you to specify x, y and z, separately. You will need to choose the "Advanced Fixture" option, at which point you can set-up a Cartesian reference if you specify a plane perpendicular to your z-axis, in the 'reference' input box (the box should be pink, I believe), then there should be options for "dir-1", "dir-2" and "normal", which corresponds to x, y and z. The last thing to select is the surface for applying the fixture to.  If the software won't allow that, you might have to call your VAR to get them to fix it. I hope that helps!