How to check if the FEA report is good?
Learn how to briefly check an FEA report, even if you don't have a deep technical training.5 December 2022
Recently I asked a lot of my subscribers what they think is the most difficult thing in FEA.
While “interpreting results” or “too much theory in materials” appeared quite often, I also got several answers like:
My biggest obstacle is actually understanding the mathematical concept behind it. Although I am really interested in the application but I believe understanding the maths behind it will be extremely useful.
As I wrote few emails about it, I figured it will be more efficient to collect the thoughts into a post – so I can simply link to it in future : )
This is a very important question I think. Whatever you think about it at least a LOT of your time is at stake!
It doesn’t really matter if you are just starting with FEA or you want to go into nonlinear or explicit analysis. If there is something new you want to learn there is a choice you need to make:
Do I want to learn math and theory or not?
Whatever is your answer, learning that theory, understanding math etc. is a very time-consuming task. Which most likely mean it makes sense to consider if it is even needed : )
Below I want to show you how I think about it, and put some arguments forward. Bear in mind that this is not an “ultimate” answer but rather my approach to things. Most likely it comes from my past experiences, philosophy and who I am.
I write this with a bit of courage though, as a few months ago I asked several of very good FEA experts about this. I asked them without showing my position on it (not to suggest anything) and it seems most of them agreed with my opinion.
However, I don’t want to convince you about this – much rather I would love to know your opinion! It would be great if you could share your thoughts on the matter in the comments below!
To start with the topic I think it is best to say that FEA is a tool. A very complex one, but still it serves a purpose and you use it.
What you want from FEA is to model something correctly, and obtain results that interest you. This can be anything from stresses to vibration frequencies. I don’t want to go into specifics here. What is important is the “process”:
FEA works like this:
To this end, it is exactly like using a calculator!
You define the problem by punching it in, calculator solves the problem and then gives you an outcome. It’s up to you what you will do with the outcome.
Ach, this is one of my favorite questions… I don’t know!
I’m using one each day, but I would not be able to build it, fix it or even explain to my kids how it operates! I understand that this has something to do with a lot of “zeros” and “ones” but that is about it. I’m a civil engineer and I wouldn’t be able to build a single logic gate if my life depended on it!
The same goes for my car, or the computer I’m using right now… things just work (i hope!).
So the important question arises – is the knowledge of how things work important?
The answer is obvious: of course, it is!
But there should be a second question here which is: to whom?
And this is a bit more difficult : )
I think that how things work is a very important knowledge… to people who want to make those things.
To drag the example a bit more, if you like to manufacture calculators it is critical to understand how they work! But is it that important in using them? I dare to disagree… after all, I do use mine and so far nothing bad happened 😛
The same goes for cars (nope, I’m not this kind of guy who can build their own car from few screws and board), computers and the rest of what surrounds us.
I’ve read somewhere, that there is not a single person on the planet who knows how to make a computer mouse. Ranging from plastic injections to optics and electronics the scope of knowledge to gain is simply too big!
And yet… we all use one, don’t we?
The understanding math behind FEA, all those algorithms and equations is critical… if you want to write your own solver. This is an incredibly difficult field (for complex nonlinear problems at least), but definitely a path to consider. Is there a business there to be made? I have no idea – this is not my path!
If like me you want to use FEA as a tool in design things are a bit different. I think in such case it makes no sense to learn how FEA works with great details. Just as with calculator it is far more important to know what questions to ask and how to interpret outcomes!
Sure I will make few benchmark tests to see if the FEA soft I’m using “actually works” – but this is a completely different thing that checking equations manually…
Just be aware that “not learning how math works” does not mean you can simply ignore the method completely. There are things like “stress averaging” or “convergence” that you need to be aware of to correctly interpret results. You don’t have to solve the math, but being aware of the potential traps is very important!
I think this “quest” to learn theory comes from universities. After all, the theory is something that is easiest to teach. And since no one likes to look bad it is better to say that this is the most important thing there is! (let me just once more say that it really is the most important thing… if you want to create your own solver!). You know organizing laboratories for all students taught by experience designers sounds nice! But since each design takes weeks to do (not to mention teaching in the process!) it is more or less impossible to organize. Even if there would be a will to do so…
I think that “understanding math” and “designing with FEA” are two completely different paths. While creating your own solver must be fun (och, I would love to know that all!) there is also a lot you need to know about design.
The design is neither easier or more difficult than “math” in FEA… it’s just a different skill set!
You don’t solve equations but instead, you will have other problems. The things like “how to support my model so it makes sense” or “how to interpret outcomes”. Those things don’t get any easier with understanding math I’m afraid. Not to mention all the additional things you need to know to design something with FEA from “what failure modes should I check” to “what are the code requirements”.
Sure that there is an overlap here, but if you want to practically use FEA I would focus far more on practical aspects of it! Sadly there are not a lot of materials and courses teaching that… which is an additional problem (and hopefully a chance for me and my blog!).
I hope this gave you something to think about! As I wrote at the beginning I don’t aim to convince you, but simply to provoke some considerations. I would love to know what you think about it. Share your ideas in the comments below, so we can further discuss this!
This is awesome! I’ve prepared a special free FEA course for my subscribers. You can get it below.esson there!
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