Siemens PLM Software Blog

In my last post, I discussed how the technology landscape is changing. Of course, I’d probably be remiss for not pointing out that Siemens PLM customers are already benefiting from these new technologies. Synchronous Technology is not some concept discussed in PowerPoint or only existing in prototype software. It’s not in beta or in some separate application, and it doesn’t force you to pick a design methodology when you buy the software.

With Solid Edge ST3, you can even mix the methodologies within the same part. Compared to other history free (direct, explicit, pick your buzz word) products, this has some advantages in places where having a certain order can help.

In this post, I’m going to focus on geometric modeling you do for finite element analysis but I’m sure most of you can extrapolate out to other examples that have nothing to do with FEA.

The example here is a industrial light shield used to place over an empty bulb to protect it. There are likely 100 ways to design this trying to keep the rain off the bulb, making sure it doesn’t bend too much, protecting better from the sides, birds, whatever.  Since history free seems to be the new “fad”, the CAD user uses synchronous technology (ok, its not a fad. Using synchronous is easier to do and handles unpredicted changes much better.)

Now we want to test this initial design by doing an FEA analysis. Because it is a thin part it requires some different handling. For sheet metal it is usually best to use a 2D mesh based off a surface – usually a mid surface through the middle of the part (BTW, 2D meshes are common in higher end FEA tools but aren’t always found in integrated FEA tools – does your CAD system support 2D meshes?)

This is not the best way to mesh thin parts

A 2D mesh is usually the better way to go

Since our FEA study now uses a surface, we can do things like remove holes, resize it, or make cuts in the surface to better control where loads and constraints are added.  For example, anything that hits our light protector in the real world is not likely to hit the entire front face. More likely, it will hit an edge or just a piece of the face. In this example we will model it hitting just the left corner by adding a cut to the surface and applying the force only to that outer corner. We will constrain the four holes in the back as if they are bolted down.

The Mid Surface

Mid Surface with corner for force

We run the analysis and get our results showing higher stress around the corner and gussets.

Now that was a pretty common scenario but what is far more interesting is how quickly you can make iterations to refine your design. For the geometry changes, you want the ease of modification of history free modeling.  For the analysis, you want the ordered update you get with a history based system. You don’t want to re-mid-surface, recreate the cuts and maybe even have to reapply loads and constraints. Ideally, you don’t want to have to transfer all the data to another application, swap apps, or change user interfaces.

The video below shows how easy it is to change your design and then reanalyze the model.

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