SimDesigner Fatigue for CATIA V5: Fatigue Analysis for the Design-Engineer, Part 1
Adarsh Pun, Mark Bacchetti and Antoine Reymond, MSC.Software Corporation

MSC Software offers a fully embedded fatigue analysis solution for CATIA V5. SimDesigner Fatigue (SFA) is an integrated solution for design-engineers and analysts who need strong collaboration in the CATIA V5 environment.

This is the first article in a two-part series on SimDesigner Fatigue. The first piece will discuss how a design-engineer can utilize SFA during the design process. The second article will talk about the powerful analysis features integrated into SFA.

With SimDesigner Fatigue, the design-engineer can use fatigue predictions to develop robust designs early in the product development stages. The simple and intuitive interface allows design-engineers to quickly and efficiently perform fatigue analysis.

This example will illustrate a design-engineer's analysis on an ATV lower control arm. A SimDesigner Fatigue analysis is linked to a CATIA CATPart through an existing SimDesigner linear static analysis (Figure 1). As a result, the design is fully generative and allows the design-engineer to make quick iterations based on the analysis results.

Figure 1: SimDesigner Fatigue process flow.

The design-engineer can quickly assess fatigue life by using three simple steps:

1. Create a Fatigue Material
2. Insert a Fatigue Case
3. Compute and review computed life

After completing this process, the design-engineer can use SimDesigner's generative capabilities to fix selected areas.

1. Create a Fatigue Material
Right click on the Isotropic Material.1 and choose Fatigue Material. A panel displaying the properties being used to automatically create Fatigue Materials data is displayed. The UTS field is highlighted to allow the User to check and re-enter this property, as it is sometimes not specified with the parent part property or not correct for the temper/alloy being used. The User should also select the Material type to ensure generation of the correct fatigue materials data.

Figure 2: Creating a Fatigue Material

2. Insert Fatigue Case
Insert a SD Fatigue Case and choose a SimDesigner Linear Static Case Solution. The fatigue analysis will use the stress results associated with the Linear Static Case for performing a Fatigue analysis at the default element centroid location. The User has the option of changing the results location to nodal or element nodal. In the image below, the nodal results location has been chosen.

Figure 3: Referencing a linear static analysis to a fatigue case

3. Compute and Review
We are now ready to assess fatigue life (Figure 4). Keep in mind that SimDesigner Fatigue will automatically cycle the stress at every node or element using a fully reversed load time history to make a quick assessment of Fatigue damage on the part.

Figure 4: SimDesigner Fatigue Computation Process

SimDesigner Fatigue displays fatigue results in an easy to understand format for the design engineer by contouring areas of the model by confidence levels on the specified service life - red where design life has not been met, green to indicate where design life has been achieved and blue indicating over design. This plot can be generated by choosing the confidence level image from the Generate Image panel (Figure 5).

Figure 5: Image Generation

In addition, the design-engineer can take advantage of SimDesigner's generative capabilities. After running the first analysis, we can see that the shock mount has some areas vulnerable to fatigue damage. The User can make the tab thicker in CATIA V5's Part Design workbench. Immediately after changing the part, we can be re-computed for a new solution. The design-engineer can also use the generative capabilities in CATIA V5 to remove material in over-designed areas and test how different materials affect fatigue life.

Figure 6: Design Iteration with SimDesigner Fatigue

In the second article, we will describe how the engineer or analyst can perform advanced fatigue simulation with SimDesigner Fatigue. We will improve the ATV lower control arm design by understanding how the component responds to realistic multi-channel loading operating environments.

For more information on SimDesigner Fatigue and SimDesigner for CATIA V5, please visit the following websites:
SimDesigner Homepage
SimDesigner Fatigue