MV-3040: Durability and Fatigue Tools

In this step, you will use the Fatigue Prep Wizard to convert an H3D file into an FES file.

1. Start a new MotionView session.
2. Select the MBD Model window.
3. From the menu bar, click Flex Tools > Fatigue Prep.

   
   
   Figure 3. Fatigue Prep Wizard

   The form shows the set of file translations that are possible using the Fatigue Prep Wizard.
4. From the drop-down menu, choose H3D to FES. Then click Next.
5. Specify the H3D file sla_flex.h3d, located in the mbd_modeling\durability_fatigue folder.
6. Specify the FES file as <working directory>\sla_flex_left.fes.

   
   
   Figure 4. Fatigue Prep Wizard

7. Click Finish.
   The Altair flexible body pre-processor is launched and the FES file is created in your <working directory>.

   Using the Fatigue Prep wizard, you can convert your results files to .fes, .asc or .dac files. You can use these files for fatigue and durability analysis in Ncode’s FE-Fatigue software.

In this step, you will convert the results of an ADAMS run to DAC files using the Fatigue Prep translator.

1. Start a new MotionView session.
2. Select the MBD Model window.
3. From the menu bar, click Flex Tools > Fatigue Prep.
4. From the drop-down menu, choose REQ to DAC. Then click Next.
5. For Select req file, click the file browser button and specify the req as indy.req, located in the durability_fatigue folder.
   Note: The DAC file format does not support unequal time steps since only frequency is specified, not each time step. Therefore your REQ file needs to have equal output time steps.
6. For Select DAC file, click the file browser button and specify indy.dac as the output file name in <working directory>.
7. For Y Type, choose Displacement.
   The Y request and Y components will automatically populate the next fields.
8. Select the first five Y requests and the first three Y components.

   
   
   Figure 5. REQ to DAC translation

   Note: You can select any number of Y requests and Y components for REQ2DAC conversion.
9. Click Finish.
   The message 'Translation complete' is displayed on the screen. MotionView generates 15 DAC files for each combination selected.
10. Click Cancel and close the window.
11. Change the application to HyperGraph 2D.
12. From the Build Plots panel, load the file indy_D_997000_X.dac from your <working directory>.
    Note: In this filename, D represents Displacement, 9970000 represents the request number, and X represents the component. This is how you get the information about the DAC file you are plotting.
13. To see the plot, click Apply.
    Note: You can plot the results from the original REQ file for comparison.

Now you will learn to use the Flex File tool.

1. Start a new MotionView session.
2. From the menu bar, click Flex Tools > Flex File Gen.
   This displays the Flex File Generator dialog. The dialog lists the files you will need for the conversion.
3. Use Save the *flx file as and specify the destination of the file as <working-dir>\sla_flex.
4. In the Number of Flexbodies field, enter 2 (the model includes two lower control arms as flexible bodies).
5. Use the Select model source (*.gra) file browser to select the sla_flex.gra file from the durability_fatigue folder.
6. Use the Select result source (ASCII *.res) file browser to select sla_flex.res file from the durability_fatigue folder.
7. Use the first Select flexible body source (*.h3d) file browser to select sla_flex.h3d file from the durability_fatigue folder.
8. Use the second Select flexible body source (*.h3d) file browser to select sla_flex_m.h3d file from the durability_fatigue folder.
9. Under ID, enter 10404 and 20404 for the two H3Ds respectively.
   These values should correspond to the actual IDs of the flexible bodies in the ADM input deck of the ADAMS solver.

   The deformation of these flexible bodies during animation can be scaled using the Def. Scale field. In this case, accept the default value of 1.000.

   
   
   Figure 6.

10. Click OK.
    This will launch the translator and create the FLX file in the destination directory.
11. In the Select application list, choose TextView.
12. On the Standard toolbar, click (Open Document).
13. Open the file sla_flex.flx.
    You should see the following contents of the file:

    
    
    Figure 7.

    Note:

    To load transients results for selected time intervals check the Optional flx statements check-box to enter the Start Time, End Time and Increment.

    To load selected mode shapes from modal animation files for models with one or more flexible bodies, check the Optional flx statements for linear analysis check-box to enter the Start Mode and End Mode.

    Additional statements are inserted in the FLX file reflecting the above mentioned parameters.

In this step you will view the Fatigue results in the animation window.

1. Use the Select application drop-down menu, choose HyperView .
2. On the Standard toolbar, click (Open Model).
3. Use the Load model file browser to select the file sla_flex.flx.
   The Load result field will automatically populate with the same file name.
4. Click Apply.
   You can use the (Start/Pause Animation) button to animate the model. Observe the model, which is a combination of rigid multi-bodies and two flexible lower control arms.
5. On the Results toolbar, click (Contour).
   You can choose different options from the Result Type drop-down menu to view the various results available in the analysis result files.

   Tip: For a detailed description of writing a fatigue analysis file from here, refer to the Fatigue Manager topic in the HyperView User’s Guide.