Finite Element Analysis (FEA) workflow

When I first started working with Finite Element Analysis I had a huge problem in understanding what to do. I had a basic engineering knowledge but I simply did not understood what was the order of the steps. Suddenly the software had many "modules" and each was screaming at me that some data is missing. Not to mention that apparently I was using 2 software solutions at the same time and I was even unaware of it!

It took me some time to realize how things work, as I had to learn that by myself. If you are in similar spot right now, below I will give you the FEA workflow with short descriptions what to do in each step.

Step 1: Geometry

This is the part that is the most obvious. Whatever you will do, it is best to implement geometry "somehow" into the system. Imagine we want to design a cantilever that looks like this:

The first thing to do would be to implement geometry of this example into our software. You can do this in 2 ways:

• Geometry import from CAD: A very popular solution where you don't do geometry in your FEA pre processor. This assumes that you actually have a 3D model of the part made my someone doing CAD in your company. Software like Inventor or Solid Edge have much more "possibilities" when it comes to creating geometry. In many pre processors there are only basic functions when it comes to this aspect, so creating a geometry in an "external" program and importing it makes sense.
• Creating geometry in pre processor: This is a second approach. Instead of using other programs to do it you can simply create the geometry in the "FEA software" from scratch.

You should know that both approaches have good and bad sides. Depending on what you do, and what type of 3D model you can get it is better to switch approach. Without a doubt importing geometry is more popular approach. But be aware that sometimes when you get a 3D model it is simply less work to do it once more than to "clean it up". But this is a topic for completely different post all together!

At this stage you should also decide whether you will model your case as a solids shells or beams (or a mix of those). This is a very broad topic, for now let's assume that we are making a solid model.

A small twist: you don't need the geometry! Literally when solver will do the calculations it won't even "see" it. This means that you can only create mesh without geometry and it will still work (equally well). This has sense in some situations but most likely you will do geometry at the beginning anyway! This is because geometry makes it easier to make mesh most of the time :) There are also other advantages we will discuss later on.

Also sometimes creating geometry requires some additional steps. Sometimes you need to make "an assembly" out of the parts you have created (so the software knows where are things in relation to each other in space). This is however software dependent (and usually pretty easy to do as well).

Step 2: Material / Boundary conditions / Loads

I didn't break this up into smaller steps as I tend to think about it as a "one" thing. When you have the geometry the most difficult part (at least for me!) is done! Now you need to do the more demanding tasks.

• Material properties: At the very minimum you need to explain to the software which part is made of what material. This is however not everything! Even when you decided what materials shall be used you should also decide what material models will you consider (i.e. will material be linear elastic or will have plastic behavior or something else). I have described some material models here.
• Boundary conditions: I'm tempted to say that this is the most important part of FEA. Without a doubt you need to support your model in order to calculate it. Just be aware that this is actually more complex than it may seem! I have made a case study about BC based on one project we have designed at Enterfea.
• Loads: Without the loads there is nothing to analyze right? Again a lot can be said about applying loads. Just remember that there are different types of loads.

Note on geometry applied loads / BC: We haven't meshed our model yet. This means that BC and loads are applied to geometry rather than mesh. Usually this is a good idea, but it may not be possible in some cases. As a rule I prefer to load and support the geometry rather than mesh (both are doable). Thanks to such approach, when I re-mesh my model (i.e. to make mesh refinement) I won't have to check / correct the loads and supports.

Somewhere here you also define contacts and contact properties. This is however a bit more advanced thing.

Step 3 and 4 and...

Read the full text on my blog!

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