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4. Analysis in I-DEAS

In this section you will prepare the model in a way that it can then be solved by the software.

Switch to the task Boundary Conditions. In this task, you will set up the wind forces acting on the motorcycle's cross-section.

Figure 1.45
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You will now set up the type of problem as Potential Flow. Select the arrow next to the first icon, as shown in Figure 1.46.

Figure 1.46
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In the expanded list of icons, select Potential Flow
Figure 1.47
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In the upcoming dialog you will need to select the wind-tunnel template as the object for which Potential Flow will be computed. Because the cross-sectional curve was the last item added to the model, it is by default selected. Click on the button Get next to the label Part or Assembly.

Figure 1.48
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In the upcoming list of parts, you will find both the wind-tunnel and the name of the cross-sectional curve. Select wind-tunnel, and click OK.

Figure 1.49
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Once you have left the previous dialog, you will notice that the wind-tunnel box is now outlined in the modeling window. Click OK in the FE Model Create dialog to return to the modeling window.

Figure 1.50
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You will now apply a force, which in terms of a Potential Flow problem is the velocity of the fluid acting on the model (in our case the fluid is wind). Click on the Force icon, as shown in Figure 1.51.

Figure 1.51
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You will first select the edge where the wind is "applied". Move your mouse over the left edge of the front face as shown in Figure 1.52, and select it with your left mouse button, then click the middle mouse button to signal that you're done with selecting.

Figure 1.52
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Because the edge is part of two separate faces, you will now need to select the face along which the fluid (wind) flows. Move your mouse over the front face, as shown in Figure 1.53, and select the face with your left mouse button.

Figure 1.53
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In the upcoming dialog, change the type of force from Intensity to Total Force. In the field labeled In Plane Force, enter a value of 400 and click OK. 400 Newtons for this wind-tunnel corresponds to roughly 50 meters/second (= 180 km/h = 112 mi/h).

The math behind the conversion is rather simple: The wind-tunnel has a height of 8 meters. A total force of 400 N is thus applied over the distance of 8 meters, which in turn means that 400/8 = 50 N are applied to each unit of 1 meter. 50 N in the case of Potential Flow are synonymous with 50 meters/sec.

Figure 1.54
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Once you have applied the force to the edge, you will see a series of arrows pointing from the edge along the face towards to front of the motorcycle cross-section.

Figure 1.55
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Next, you will apply a Displacement Restraint to keep the wind-tunnel from blowing off the screen. Click on the second icon on the fourth row as shown in Figure 1.56.

Figure 1.56
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Select the edge on the right-most side of the front face with the left mouse button, and hit the middle mouse button to signal that you're done with selecting.

Figure 1.57
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Accept all the default values in the upcoming dialog by hitting OK.

Figure 1.58
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You will notice that a Displacement Restraint has been applied by a series of arrows pointing on different directions on the right-most edge.

Figure 1.59
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Next, you will finalize setting up the Boundary Conditions. Click on the first icon on the 6th row, as shown in Figure 1.60.

Figure 1.60
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In the upcoming dialog, place a check mark next to Restraint Set and hit OK. This activates the conditions you have just set-up.

Figure 1.61
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You will now switch to the Meshing task, in which the model is broken down into much smaller entities, which are then used to calculate the potential flow.

Figure 1.62
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First, you will define the size of the mesh. Click on the first icon as shown in Figure 1.63.

Figure 1.63
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Next, select the front face, which is the surface you are defining the mesh for. Move your mouse cursor over the front face and select it with the left mouse button, then hit the middle mouse button to signal that you're done with selecting.

Figure 1.64
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In the upcoming dialog, specify the numeric value 0.06 in the field labeled Element Length and hit OK. You may try out differently sized meshes, but a size of 0.06 works just fine for this wind-tunnel.

Figure 1.65
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Now that you've defined the mesh, you will proceed with creating the mesh. Click on the third icon in the first row, as shown in Figure 1.66.

Figure 1.66
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Move your mouse cursor over the front face and select it with your left mouse button, then hit the middle mouse button to signal that you're done with selecting.

Figure 1.67
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At this point, I-DEAS will create a mesh on the front face of the wind-tunnel. This may take a few seconds, so be patient. After I-DEAS has completed meshing the surface, you will be prompted with a dialog asking you whether or not to keep the mesh. Select Yes.

Figure 1.68
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You have now meshed the front-face of the wind-tunnel.

Figure 1.69
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You will now switch to the Model Solution task, so as to set up solutions of interest.

Figure 1.70
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You will now create a solution set. Click on the second icon, as shown in Figure 1.71.

Figure 1.71
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In the upcoming dialog, click on the button Create.

Figure 1.72
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In the next upcoming dialog, click on the blue-colored icon, as shown in Figure 1.73.

Figure 1.73
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In the following dialog, make sure that LOAD SET 1 is selected in the list of Load Sets, and click OK on all three dialogs.

Figure 1.74
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You will now initiate the solution process. Click on the arrow next to the icon featuring a green arrow pointing to the right, as shown in Figure 1.75.

Figure 1.75
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In the expanded list of icons, select Solve to start the solution computation.

Figure 1.76
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I-DEAS will now switch applications. In the upcoming dialog hit Dismiss.

Figure 1.77
If there are no errors in the model, I-DEAS will now start computing. A graph like the one in Figure 1.78 show the progress.

Figure 1.78
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Once the solution has been generated, I-DEAS will switch back to the previous application. In the upcoming dialog hit Dismiss.

Figure 1.79