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Problem Specification
1. Start-up and preliminary set-up
2. Specify element type and constants
3. Specify material properties
4. Specify geometry
5. Mesh geometry
6. Specify boundary conditions
7. Solve!
8. Postprocess the results
9. Validate the results

Step 8: Postprocess the results

Plot Deformed Shape

The Results Viewer provides a convenient way to review results.

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Hold down the Ctrl key and use the mouse to manipulate the model view;check that the BC's and loads have been imposed correctly. The snapshot below shows one view that is useful in checking the BC's. Are the symmetry and clamped conditions satisfied at the corresponding edges for the facesheet as well as the stiffeners? Is the model deformation as you'd expect for a uniform pressure on the facesheet in the +z direction?

The maximum displacement DMX=3.88 mm. Where do you think this occurs? We'll check this in a minute.

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Select Forward Only in the Animation Controller.

Plot w Displacement

In the Results Viewer, in place of Displaced structure, choose Nodal Solution > DOF Solution > Z-Component of displacement. Click on the Plot Results icon.

The location of maximum deflection w_max is labeled MX. This occurs not at the facesheet center but on the edge x=0, at approximately y=L1/3. As expected, the deflection is zero along the clamped edges.

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For filename, enter w_contours. This creates the file _w_contours.png_ in your working directory. Check that you can open this file using your pet image viewer.

Deflection at Facesheet Center

To query the value of the deflection at the center of the facesheet, select the Query Results icon in the Results Viewer.

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Cancel the Query Subgrid Results menu.

σ_xx for Facesheet

For clarity, let's first plot σ_xx for just the facesheet. Select the elements for the facesheet in two steps:

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Utility Menu > Plot > Elements

Utility Menu > Select > Entities

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Hold down the Ctrl key and flip the model over so that you are looking at the bottom of the facesheet as in the snapshot below. Now the contours values correspond to σ_xx values for the facesheet bottom. Use Query Results to determine σ_xx at the center-bottom of the facesheet. I get -56 MPa. What do you get? The negative sign indicates compression.

(For an enlarged view, click and maximize the browser window)

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Cancel the Query Subgrid Results menu.

σ_yy for Facesheet

Results Viewer > Nodal Solution > Stress > Y-Component of stress

Click Plot Results icon. The snapshot below shows the σ_yy contours.

Using Query Results, I get the following values for the bottom of the facesheet (see snapshot above):

1. At the center, σ_yy= -28 MPa.
2. At the clamped edge location (x=0, y=L1), σ_yy= 77 MPa. What are your corresponding values?

σ_xx for Stiffeners

Currently, the facesheet is selected and the stiffeners are unselected. To plot stress contours for the stiffeners, we'll unselect the facesheet and select the stiffeners i.e. reverse the selection. This can be done using the Invert operation:

Select Entities menu> Invert

Select Entities menu> Replot

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The σ_xx values for the stiffeners in the y-direction is virtually zero; confirm this using Query Results. This means that, as expected, the load in the x-direction is carried by the stiffeners in that direction.

Let's determine σ_xx values at the top of the x-stiffener closest to the center; we'll compare these values to plate theory in Step 9. Using Query Results, I get the following values at the top of this stiffener (see snapshot above):

1. At (x=0, y=L₁/6), σ_xx= 312 MPa.
2. At the clamped edge location (x=W₁, y=L₁/6), σ_xx= -653 MPa. What are your corresponding values?

σ_yy for Stiffeners

Results Viewer > Nodal Solution > Stress > Y-Component of stress

Click Plot Results icon.

The σ_yy values for the stiffeners in the x-direction is virtually zero; confirm this using Query Results. This means that, as expected, the load in the y-direction is carried by the stiffeners in that direction.

Let's determine σ_yy values at the top of the y-stiffener closest to the center which we'll compare to plate theory in Step 9. Using Query Results, I get the following values at the top of the stiffener (see snapshot above):

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Go to Step 9:Validate the Results

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