HF-3130: Blank Shape Predictor

The Blank development process for crash formed parts requires an initial guess based on die design results. After you supply an initial guess, you run multiple iterations of forming simulations and visually inspect the deviation of the simulated part boundary from the design CAD boundary.

To solve the blank-development problem, the blank shape predictor tool tracks the boundaries of the CAD design boundary from the simulated part onto the initial blank. A resulting traced line on the initial blank can be used to run a second simulation, the part boundary of which will be closer to the design CAD boundary. Generally the Blank Predictor tool reaches the required blank shape after three to four simulation iterations. Applying a rectangular blank for the first of these simulation events can minimize the number of iterations required to reach the desired blank shape. Note that you can also use the Line Tracing feature to trace the design CAD boundary in multiple stages.

1.	Create a working directory.

2.	Copy the required files into your working directory:

•

Form.sta

•	Design_CAD_Boundary.iges

•	Line_Trace_Result_file.h3d

•	Form_Dev_Blank.hf

Note: The model files for this tutorial are located in the file mfs-1.zip in the subdirectory \hf\Incremental\. See Accessing Model Files.

1.	Launch HyperForm with the Incremental_Radioss user profile.

2.	Select Tools > Blank Shape Predictor.

3.	In the Blank STA/dynain file field, navigate to the file, Form.sta, and then click Import. The .sta file is generated after the first forming simulation with the rectangular blank.

4.	In the Target line field, navigate to the file, Design_CAD_Boundary.iges, and then click Import.

5.	Click the Predict tab, and move your cursor to the field for Stage1. The cursor changes to a plus symbol, as you see in the figure in step 7.

6.	In the Result file column for Stage1, click, and then navigate to the file, Line_Trace_Result_file.h3d, which is generated from the first iteration of the forming simulation.

7.	Next to Select part, click the yellow Components button twice, and then click an element on the model in the graphics area.

predict_tab

8.	Click proceed.

9.	Next to Select Target lines(s), click the Lines button twice, and then click lines >> displayed.

10.	Click proceed >> Predict. HyperView opens in batch mode, and displays the predicted blank shape.

The following image shows you an overlay of the .sta file elements in transparent mode, the design CAD boundary, and the predicted blank shape:

Part_Overlay

1.	From the File menu, select Import > Model.

2.	From the Import tab, navigate to Form_Dev_Blank.hf and click Import. This file loads on top of the existing .sta file and predicted blank outline.

3.	In the Model browser, clear the display of the surface and elements for all the components except for Blank 1 and Predicted_line.

HF_3120_08

4.	From the Geometry menu, select Edit > Surfaces > Trim with Lines. On the panel that appears, set the options as you see outlined in red in the following image:

trim_lines

5.	Under the with lines header, click surfs, and then pick the blank surface from the screen.

6.	Under the with lines header, click lines, and then select the predicted blank outline from the screen.

7.	Click trim. After the trim operation, you can cut the required shape from the rectangular blank from the Delete panel.

8.	To open the Delete panel, press F2. Click the extended entity selector and change the selection to elems.

10.	Click Elems >> By Geom >> Surfs, and then pick the rectangular surface from the screen.

11.	Click add to selection and then click delete entity. The following figure shows you the new blank shape cut from the rectangular blank:

trim_shape

12.	Use the new shape and follow HF-3010. Set up a new a forming simulation and compare the simulated shape with the design CAD boundary. Repeat Exercise 1. to predict the new shape until the simulated part shape matches with the design CAD boundary.

1.	Launch HyperView.

Note: In any HyperForm user profile you can access HyperView from the toolbar by selecting Applications > HyperView.

2.	In HyperView, select File > Load > Preference File. The Preference file window opens.

3.	Select HyperForm Utilities, and then click Load. From this point on, HyperForm appears on the HyperView toolbar.

4.	Select File > Open > Model. The Load model and results panel appears below the graphics screen:

load_model

5.	For Load model, navigate to your working directory, and then select the file, Line_Trace_Result_file.h3d. Notice that the Load results field gets populated with the same path as Load model.

6.	Click Apply. The results file loads and the forming simulation of the b-pillar is displayed.

7.	From the Model browser, turn off the tools, and from the animation controls, proceed to the last time step. The part shape, the output from the rectangular shaped blank, is displayed as you see in the following image:

rectangular_blank

1.	From the toolbar, select HyperForm > Import and Trace Line. The Import Line window opens.

2.	Navigate to the file, Design_CAD_boundary.iges. The Line Trace panel opens at the bottom of the screen.

3.	With the Components button highlighted, click the part shape from the screen. Notice that the name of the blank as seen on the Model browser appears at the center of the part shape confirming your selection.

Click Create. Notice the trace of the line from the final shape to the initial blank shape is automatically displayed on the screen. The trace is shown for every time step by default. If you don’t see the trace for every time step, then animate once by clicking play from the animation controls toolbar.

5.	On the animation controls toolbar, click to see the shape of the trace on the initial blank (time zero).

trace_boundary

By default, the design CAD boundary appears in pink, and the trace of the design CAD boundary at every time step appears in gray.

6.	To export the traced shape, from the Display Options on the bottom-right corner of the screen, click Export.

HF_3120_06

The pink line is the design CAD boundary and the gray line is the trace of the design CAD boundary at time zero.

7.	Rerun the forming simulation using the traced shape and compare the results with the design CAD boundary. If the two boundaries do not match, then repeat the trace and rerun the forming simulation with the new blank shape.