Plotting X–Y graphs from field data for selected steps

Use the field data stored in the output database files, Pipe.odb and PipeRestart.odb, to plot the history of the axial stress in the pipe for the whole simulation.

This task shows you how to:

Generate a history plot of the axial stress in the pipe for the restart analysis

  1. In the Results Tree, double-click XYData.

    The Create XY Data dialog box appears.

  2. Select ODB field output from this dialog box, and click Continue to proceed.

    The XY Data from ODB Field Output dialog box appears.

  3. In the Variables tabbed page of this dialog box, accept the default selection of Integration Point for the variable position and select S11 from the list of available stress components.
  4. At the bottom of the dialog box, toggle Select for the section point and click Settings to choose a section point.
  5. In the Field Report Section Point Settings dialog box that appears, select the category beam and choose any of the available section points for the pipe cross-section. Click OK to exit this dialog box.
  6. In the Elements/Nodes tabbed page of the XY Data from ODB Field Output dialog box, select Element labels as the selection Method. There are 30 elements in the model, and they are numbered consecutively from 1 to 30. Enter any element number (for example, 25) in the Element labels text field that appears on the right side of the dialog box.
  7. Click Active Steps/Frames, and select Pull II as the only step from which to extract data.
  8. At the bottom of the XY Data from ODB Field Output dialog box, click Plot to see the history of axial stress in the element.

    The plot traces the axial stress history at each integration point of the element in the restart analysis. Since the restart is a continuation of an earlier job, it is often useful to view the results from the entire (original and restarted) analysis.

Generate a history plot of the axial stress in the pipe for the entire analysis

  1. Save the current plot by clicking Save at the bottom of the XY Data from ODB Field Output dialog box. Two curves are saved (one for each integration point), and default names are given to the curves.
  2. Rename either curve RESTART, and delete the other curve.
  3. From the main menu bar, select FileOpen; or use the tool in the File toolbar to open the file Pipe.odb.
  4. Following the procedure outlined above, save the plot of the axial stress history for the same element and integration/section point used above. Name this plot ORIGINAL.
  5. In the Results Tree, expand the XYData container.

    The ORIGINAL and RESTART curves are listed underneath.

  6. Select both plots with CtrlClick. Click mouse button 3, and select Plot from the menu that appears to create a plot of axial stress history in the pipe for the entire simulation.
  7. To change the style of the line, open the Curve Options dialog box.
  8. For the RESTART curve, select a dotted line style.
  9. Click Dismiss to close the dialog box.
  10. To change the axis titles, open the Axis Options dialog box.

    In this dialog box, switch to the Title tabbed page.

  11. Change the X-axis title to TOTAL TIME, and change the Y-axis title to STRESS S11.
  12. Click Dismiss to close the dialog box.

    The plot created by these commands is shown in Figure 1. The axial stress history of the same element during Step 3 can be plotted by itself by selecting only the RESTART curve (see Figure 2).

    Figure 1. History of axial stress in the pipe.

    Figure 2. History of axial stress in the pipe during Step 3.