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Solid Edge ST6 First Looks: Mesh Refinement and Storage

By John Evans, September 25, 2013

In this First Look of Solid Edge ST6, I will describe how the software refines model meshes, and then discuss features and issues that I noticed along the way. I conclude this article with a list of my favorite features, along with improvements I recommend.

Solid Edge ST6 First Looks: Simulation and Linear Static Stress

Solid Edge ST6 First Looks: Optimization and Validation

Mesh Refinement

For this three-part series on simulation with Solid Edge ST6, I have been working on the design of a rifle. In part 2, I meshed the bolt-chamber assembly, and Solid Edge produced a nicely balanced mesh. Despite this, I decided that the mesh could benefit from refinement:

My intention is to get more accurate results with the same or faster processing time. For this, Solid Edge ST6's mesh sizing and remesh functions come in handy (see figure 1).

Figure 1: Mesh refinement tools on the ribbon

Surface refinement involves guiding the meshing engine to repopulate the mesh with different densities. To do this, Solid Edge allows us to specify the element size. Note that we can apply the mesh sizing tool to part features, no matter whether we are in a part file or in an assembly study.

I started the Surface Refinement command, and then picked the roller button and helical contact faces. I forced the element size (for the entire surface) down to approximately 0.05". Being able to size the meshes of parts and features independently is an essential tool in FEA (finite element analysis), and I was happy once I got it working properly.

After the individual mesh adjustments were applied, there are two paths for me to follow:

Remesh Command

The new Remesh command allowed me to rebuild the mesh for components independently by picking the mesh object through the Simulation panel, and then selecting Remesh from the context menu (see figure 2). This permitted me both of the following advantages:

Figure 2: Using refinements and remeshing tools to fine-tune the mesh density

Used in conjunction, mesh sizing and remeshing can create almost any mesh arrangement necessary.

Showing Poor Quality Meshes

Another useful Solid Edge ST6 feature I should mention is the new Show Poor Quality Mesh function. After it flags a mesh as problematic, Solid Edge allows us to visualize where the mesh errors are located. It does this by converting the view to wireframe, and then shading only the damaged element faces (see figure 3). This wonderful tool eliminates the method I used to use in other applications, searching by element number to understand where the problem was. Thank you, Siemens PLM!

Figure 3: Show Poor Mesh command highlighting a mesh error in purple

(In this instance, the mesh error was caused by a mishap with multi-body modeling which then needed to be recut.)

Once Solid Edge completed the remeshing and resolving, I moved on to adjusting feature geometry, and then ultimately found a combination suitable with which to continue the required studies (see figure 4).

Figure 4: Results after design modifications

A Meshing Failure

Along the way, I tried studying the receiver and barrel assembly. The receiver is somewhat complex and I was disappointed that Solid Edge could not mesh it effectively. Eventually, I removed it from the design after I experienced terribly inconsistent meshing with gaping holes; I employed different settings in strategies and mesh refinement for an hour of simplification, but to no avail (see figure 5).

Figure 5: Receiver and barrel assembly mesh refined numerous times in an attempt to plug gaps in the mesh. In this view, there are at least three holes after remeshing; blue glyphs next to the meshes still indicate that all is well, however

Storing the Results

All simulation setup information, including optimization, is stored in the model .par file. Simulation results, however, are stored in a separate file that uses the same name but has an .ssd extension. When this results file is not present during opening of the model file, then the studies will still be present (along with their respective configurations), but the results will be missing - highlighted with a red exclamation mark in the Simulation panel.

This is actually a brilliant approach. We can archive the results separate from the model, and then continue to version the design as needed, with no problems. The results file can later be added back to the project, if desired. Alternatively, the results can be resolved. This is great for packaging our studies for sending others as a much smaller file, and they can resolve it.

Saving the FEMAP Model File

I used that mesh-gap problem I mentioned earlier to test the Export FEMAP Model function (see figure 6). I wanted to see how FEMAP would handle the difficult part. FEMAP is Siemens PLM's stand-alone FEA software that also reads files from CATIA, Pro/Engineer, NX, SolidWorks, AutoCAD, and so on.

Figure 6: Save FEMAP Model File function on the study's context menu

The meshes, settings, and results were transferred with complete accuracy. All connections and constraints were intact, and so ready to be deployed. Custom materials transferred accurately, as well - the best FEM exchange I have ever witnessed! (see figure 7).

Figure 7: The bolt-chamber assembly in FEMAP after activating the saved result

Everything was set up properly, but I needed a new, simple mesh that didn't contain errors. I deleted the original mesh, and then asked FEMAP to recalculate it. I was presented with an error-free mesh on the first run, receiving reasonable results (see figure 8).

Figure 8: FEMAP successfully remeshing and solving the receiver and barrel response on its first attempt

From this experience, I initially concluded that the meshing engine in Solid Edge is different from Femap, and so not as capable as dealing with large aspect differences in face sizes. But Siemens PLM told me that Solid Edge uses Femap's meshing APIs, but not all of them are implemented yet.

Conclusion

The Good

The Bad

There were a few things, however, that I did not like and so could be improved:

Solid Edge ST's linear static stress environment is straight forward and was easy for me to learn. I believe it would be a snap to adopt by companies who have a couple of experienced engineering technicians on staff.

I think that Solid Edge's simulation environment is valuable and with a few enhancements it will be tough to beat.

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About the Author

John Evans has 30 years experience in the aerospace design, engineering and fabrication, as well as 18 years with MEP and civil engineering. He is certified with AutoCAD Civil 3D and Inventor. More...

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