Easiest way to learn FEA?

[Anonymous]

Anyone have advice on the easiest way to pick up the ability to validate a design using Inventor 2015's in-built FEA capabilities?

I don't mind paying money for well-designed tutorials.  I'm afraid my days of hunting around gathering disparate bits of information here and there (e.g. youtube videos, answers to specific questions on internet forums, etc) to try to put together an overall sense of how to do things is probably behind me -- I feel like I have done that way too much in the past and that it was usually an inefficient way of doing things.

Inventor's in-built tutorials were really well organized and got me up to speed fast.  Any advise on how to learn about its FEA capabilities in a similar way would be greatly appreciated!

[JDMather]

I don't think there is an "easy" way, but maybe the "easiest" way is to sign up for a class.

This might get you started

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2014/inventor/md6583

There is sound with the videos.

[Anonymous]

I only see that one 1 minute video, and no other classes that discuss FEA. Is there something I am missing?

[lesmfunk]

The first thing: You cannot validate a design using FEA! I do not know an engineer who would stamp a design based on FEA.

I worked at a mechanical testing facility for 7 years and also used FEA for reducing iterations in the design process. We were once told by Algor Technical Support that you shouldn't expect more than 70 percent accuracy using FEA compared to physical results. Now, I was able to get about 95 percent on one successful test after the third try, but I had the luxury of multiple attempts (which, by the way, cost the client and my employer tens of thousands of dollars). I have seen many an engineer scratch their head when the physical test did not reveal the same thing as the FEA analysis.

Don't get me wrong, FEA is a very valuable tool in decreasing design iterations, say from 20 down to 3. It is also very good for relative comparisons between designs. But there are too many variables when trying to compare FEA to real-world.

Just keep that in mind.

[Anonymous]

You can watch some of these videos:

http://engineeringexploration.autodesk.com/

They're actually for Autodesk Simulation Mechanical, but most of the basics are the same as for Inventor Stress Analysis, as ASM is a more advanced version of Inventor Stress Analysis.

[JDMather]

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@Anonymous wrote:
I only see that one 1 minute video, and no other classes that discuss FEA. Is there something I am missing?

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II see hyperlinks to 10 videos and a 3 downloads.

I don't think this substitutes for classroom instruction though.

[Anonymous]

Yes, I recognize that the goal shouldn't be to learn FEA "as quickly as possible".  I have seen some statistics before about what the rate of actually accurate FEA results is.

Fortunately, what I need to do right now (in the next week or so) should be relatively simple and straightforward.  Basically, my boss needs me to do an initial sanity check and then FEA experts will do a real analysis if everything checks out from that.

Any suggestions on what I could do to learn about a week's worth of stuff, for immediate term needs, as efficiently as possible would be greatly appreciated.  In the long term, I will be taking a proper course on FEA about 3 months from now.

[JDMather]

Wasim Younis book.

[Anonymous]

I recently purchased the book you just linked to, Dr. Mather, in order to more completely understand the Inventor Stress Analysis user interface (the 2015 version doesn't seem to be available yet). 

Although I do see great value in the book, I'm shocked at how poorly written / edited it is.  For example, duplicate pages, duplicate paragraphs, poor grammar, misspelled words, etc... I try not to act as the grammar police, but it can make it difficult at times to understand the intent of what's being discussed.

[lesmfunk]

valbotany wrote: "I will be taking a proper course on FEA about 3 months from now"

In the meantime, it doesn't hurt to play around with the software. A few things to think about:

1. Inventor Stress Analysis is limited to predictions in the elastic range of the stress vs strain curve. You'll need ASM for simulations beyond yield.
2. Obey Inventor's suggestion to use shell elements for thin walled components. Not sure what Inventor's criteria is, but an old rule of thumb is minimum 3 elements thick when using brick elements to achieve the same accuracy as shell elements. Therefore shell elements greatly reduce processing time.
3. Consider symmetry and only perform simulation on half (or even a quarter) of the model to reduce processing time.
4. Rated material properties are not the same as actual. They are usually a minimum. Stiffness of a material is often greater. If possible, ask vendor for a mill certification/test report for the material you are using and compare it to the rated properties. This is important if you want the component to yield or absorb energy. But, always determine safety factor from rated material properties.

That's just a few general ideas off the top of my head. All of this depends on the application. Once you delve into the world of FEA, you will see that it is a very broad field. You will likely specialize in only one area.

[Anonymous]

I previously somehow overlooked this post. Will go back and look at this again.

[Anonymous]

Hi JDMather, I looked through the materials you linked and they were interesting and useful, but did not seem to contain step-by-step type information on how to actually carry out an FEA analysis.  As such, I feel they were not quite what I was looking for.

Any further advice on learning how to carry out an FEA on Inventor would be greatly appreciated.

[JDMather]

That information was just a basic introduction - just enough to get you into trouble.

That was only a 1.5hr presentation.

Get the Wasim Younis book 1.  (search Amazon.com)

[lesmfunk]

The Inventor Stress Analysis ribbon is structured in order left to right, as is the browser top to bottom. Or you can use the guide:

Go for it!

Just make sure you start with something basic that you (or someone else) can verify with hand calculations. This will give you a little more confidence in your methods when you get to more complex designs.