Analyze the Results

Analyze the results of the simulation to determine the efficacy of the O-ring.

When parts come into contact during a simulation, you should review the stress, deformation, and contact pressure results. You should also confirm that the contact pressures developed during the simulation do not cause the parts to exceed their yield limits.

In this example, you examine the von Mises stress, displacement, and contact pressure results at the end of the simulation.

  1. When the simulation completes, Physics Results Explorer displays the von Mises stress contour plot for the last solution step.



    The global max of the von Mises stress value is 7.57e+7 N/m2, which is less than the material yield value of 2.068e+8 N/m2.
  2. To display the maximum value in a contour plot, do the following:
    1. From the Display section of the action bar, click Show Min/Max values .
    2. In the context toolbar, select Show only Max value , and click OK .
  3. To display the displacement plot, do the following:
    1. In the Plots panel, from the Plot options, select Displacement.1.
    2. Select the last row to display the results of the last time increment in the static step.



      The top plate has a maximum displacement of 1.47 mm, as expected. The deformed shape of the O-ring indicates that it stretches laterally as the top plates pushes it into the groove. The O-ring's maximum compression ratio is 1.47 / 5.64 = 26%, which is an acceptable ratio (5.64 mm is the largest diameter of the undeformed O-ring's cross-section). For most elastomer O-rings used as static seals, the maximum recommended compression ratio is 30%.
  4. Display the contact pressure contour plot, and configure it to show only the results of the O-ring.
    1. In the Plots panel, from the Plot options, select Contact Pressure.1.
    2. From the Display section of the action bar, click Display Group .
    3. Clear the Top plate and Groove options.
    4. Click Replace selected to display only the O-ring's results, and click Close.



    The contact pressure results are visible for the O-ring only. The contact pressure is highest at the top and bottom surfaces of the O-ring, and considerable pressure developed between the side surfaces of the O-ring and the groove walls. The O-ring seals the vacuum chamber efficiently.

    The percentage of volume that an O-ring's cross-section displaces in its confining space (or gland) is called “gland fill.” Most O-ring seal applications require a gland fill between 60% to 85% of the available volume, with an optimum fill being 75% (or 25% void). It is essential to allow at least a 10% void in any elastomer sealing gland to compensate for thermal expansion and O-ring swell.

  5. Save your work.

Congratulations, you have successfully completed this example!