Tips On Calculating Accurate Stresses With Altair SimSolid

SimSolid is a very easy to use code for calculating accurate stresses. This shows an exceptional range if you think about it: it is most famous for being a code that lets you quickly analyze large assemblies. But stress analysis can be the other end of the spectrum, zooming in to get a localized result at a stress concentration. Simsolid does very well at that also.

Normally when you run SimSolid, you can just accept the default settings. This will run very quickly and do a good job of calculatiing more global quantities such as displacements or modal frequencies and mode shapes. It will also identify where local stress “hot spots” are. You can stay in this mode while comparing design alternatives. But this solution, the “first stage”, may not get accurate stresses.

For that, the next step is to run and additional solution with some easy tweaks to the settings, the “second stage”. For smaller models this can be just using an “adapt to features” checkbox. For larger models you select on or more parts where the first solution has shown higher stresses, and turn on adapt to features for those parts only. This second stage solution may be slower than the first but will typically still be a lot faster than trying to do adaptive analysis with FEA codes.

I have described this procedure in detail in the document “Accurate Stress Analysis With Simsolid” available here. This explains some subtleties from a user’s perspective, including issues like dealing with singularities, as well as giving an overview of the theoretical background.

The initial solution in SimSolid identifies the max stress to be at the root of the notch:

Now we move on to stage II to make sure the stress is accurate. Under solution settings, select the specimen part, check adapt to features, and rerun:

The stress is now very accurate. This is one of the models from the “real world” validation cases I did for SimSolid, available here.

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