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2. Preparations in StudioTools

While the curve profile of the motorcycle can be modeled in I-DEAS, we will model it in StudioTools, since we are more familiar with it already. In order for the curve to be seamlessly accepted by I-DEAS, it must be prepared in a certain way in StudioTools. The curve of the motorcycle profile must obey the following points:
  • Watertight: The curve may not have any gaps or holes, e.g. if the curve is made from several pieces, all end points must be magnet snapped and joint to the next start point. It is highly recommended to use no more than one curve for the entire profile.
  • Correct dimensions: The curve must remain within the boundaries of the provided template.
  • Motorcycle placement on a pseudo-street: While it is theoretically possible to place the motorcycle in the center of the wind tunnel, and having it float above ground, this scenario is not terribly realistic. We must instead place the motorcycle on a ground level. Because there exist a few issues with placing the motorcycle on the bottom face of the wind tunnel, we will instead draw the motorcycle on an elevated street level, i.e. a slight hill (see below). Make sure that the hill does not contain any sudden bumps, as it is not the hill we would like to analyze for aerodynamic properties, but instead the motorcycle. More will be explained below.

Open the template PotentialFlowTemplate in StudioTools. You will only be using the Side View for this exercise, so you should maximize the Side View frame.

Figure 1.6
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For this tutorial, we will use an image of a motorcycle with a rider to model the cross-section. You could just as well use an exisiting model and trace the outline of it, but it is generally easier to trace from an image.

To import the image, click on File -> Import -> Image plane.

Figure 1.7
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Find the image, whose outline you would like to use for the cross-section.

Figure 1.8
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When importing the image, its size is reflected by the size of the Side View.

Figure 1.9
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Scale the image plane to fit the motorcycle outline in the template. You may wish to zoom in, in order to scale the bike correctly.

Figure 1.10
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The image in the image plane is rather bright, and tends to make it difficult to distinguish the CV curve you are about to build. You may thus elect to dim the image by going to DisplayTgls -> Object toggles and click on the box next to Image planes
Figure 1.11
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In the following dialog box, click on Dim/Undim, as shown in Figure 1.12. Finally hit Go to dim the image plane.

Figure 1.12
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You will now begin to construct the CV curve. In addition to drawing the cross-section of the motorcycle, you will be constructing the elevated street in the same step.

Start the CV curve at the left lower corner of the templated street by placing the first CV, as shown in Figure 1.13.

Figure 1.13
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Place 3 or 4 more CVs along the elevated street, as shown in Figure 1.14.

Figure 1.14
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Continue placing CVs along the front tire of the motorcycle. You do not need to place CVs sparingly - use as many as needed to approximate the cross-section best. Whenever you come across sharp corners, place 3 CVs close to each other.

Figure 1.15
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Regardless of number or shapes of indentations in the cross-section, approximate them by placing CVs. In Figure 1.16, you will notice a strange open area between the rider's back and the seat. Even this gap is included in the curve cross-section.

Figure 1.16
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Towards the rear tire of the bike, we continue placing CVs up to the point where the curve hits the intersection of tire and street.

Figure 1.17
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At this point, we place the next CVs on the templated street level.

Figure 1.18
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Finally, we finish the entire cross-section by Magnet Snapping the last point to the first point of the curve. In order to obtain a sharp angle such as the one in Figure 1.19 at the right-most side of the hill, you first place a CV at that point, then you Magnet Snap 3 more CVs to that very same point.

Figure 1.19
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We now remove the image plane from the scene.

Figure 1.20
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We also remove the template from the scene. In the Pick palette, click on Template, then click on any of the gray edges of the template. Finally, click on Delete.

Figure 1.21
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The only remaining object in the scene should be the cross-sectional CV curve.

Figure 1.22
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To save the model as a file type that is recognized in I-DEAS, go to the File menu, and select the box next to Save as.

Figure 1.23
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Under File Formats choose the file format STEP. STEP is the international STandard for the Exchange of Product Model Data, which has been developed by the International Standards Organization (ISO) in conjunction with American, European, and Asian businesses and government agencies to implement a standard for transferring electronic data. You will find that STEP is commonly available among CAD/CAM/CAE software packages, while the StudioTools WIRE format is proprietary to Alias|Wavefront software packages.

Figure 1.24
Leave all available options set to their defaults, and click Save.

Figure 1.25
Give your model a name, and save it. The file extension stp will be added automatically, so you merely have to type in the name of your model file.

Figure 1.26
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