Step 6: Numerical Results

Total Deformation

First, examine the total deformation by clicking on the Total Deformation object in the tree. Turn on the Undeformed Wireframe as shown below.


With 10 line elements, you should see the following output for the total deformation.

https://confluence.cornell.edu/download/attachments/125812731/10ElemTotDefCornellian_full.png

If you turn off View > Thick Shells and Beams, you will see the deformation of the line elements. The 3D beam view is constructed from this. The maximum deformation is 0.0051 m which matches the hand-calculation value from the Pre-Analysis.

When ANSYS displays the beam deformation, it just connects the displacements at nodes by straight lines. The display ignores the fact that we also have the slope at the nodes. So you'll see an unphysical-looking kinked line in the deformation display. This is a shortcoming of the display, not of the underlying beam element formulation. You'll see the displayed deformed shape getting smoother as you refine the mesh.

The beam deformation can be animated by clicking on the play button, , which is located underneath the beam deformation results. This will interpolate between the initial undeformed and final deformed configurations.

Maximum Bending Stress

In order to examine the maximum bending stress first expand the Beam Tool folder, , which is located under "Solution(A6)". Next, click on the Maximum Bending Stress button, .

Note that in this display, ANSYS shows the same value across the cross-section. This visualization is misleading. The maximum bending stress occurs only at the top fiber. The value that ANSYS reports is 4.635 MPa which matches the value from the Pre-Analysis exactly.

Bending Moment

To view the bending moment along the beam, click Total Bending Moment in the Outline window. You should see the following in the graphics window.

https://confluence.cornell.edu/download/attachments/125812731/BendingMoment.png?version=1&modificationDate=1316567309000
Also notice that the values were plotted in a graph in the Graph window and also displayed in a table. The values can be exported into a Excel or text file by right-clicking on the table.

https://confluence.cornell.edu/download/attachments/125812731/Graph.png?version=1&modificationDate=1316567430000
In the above, pay close attention to maximum and minimum values of the bending moment. At the left end, the bending moment is 32000 Nm; the calculation for moment is

$
M = F \times d = (8000 N) \times (4 m) = 32000 \mbox{ Nm}
$

So this checks out. We also notice that the minimum moment 1.1278E-10 Nm. Because this value is over 1E-14 smaller that the largest value, it can be assumed to be zero to machine precision.

Directional Bending Moment

To view the directional bending moment along the beam, click Directional Bending Moment in the Outline window. You should see the following in the graphics window. The Directional Bending Moment gives us the sign along with the magnitude.


click here for full view


click here for full view


Go to Step 7: Verification & Validation

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