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Active Member
Jake_Clark/Alderon
Posts: 6
Registered: ‎07-17-2012
Message 1 of 14 (945 Views)
Accepted Solution

Stress Analysis

945 Views, 13 Replies
07-17-2012 02:06 PM

Hello, I am student using Inventor 2010 Stress Analysis and I'm having some problems interpreting the results.

 

My main concern is making sure that that part doesn't break. And I read somewhere that you look at the safety factor for that?

 

Also, the displacement is throwing me off. The program is saying 0.004 for a displacement when it looks something like 0.160 (measurement aren't exact).

 

Any answers or links to other sites would be greatly appreciated!!


conklinjm wrote:

... this value usually ranges from as low as 1.2 up to as high as 10. The higher the value -- the more uncertainty in the model...


Wrong.  Need to go back to school.

What book are you using to learn FEA?

 

Jake, your professor should be covering these topics in class - this is an advanced topic.

Search Amazon.com for Wasim Younis book.

Search http://au.autodesk.com for classes by Younis and others on FEA.

Go through the built in Help>Learning Tools>Tutorials

 

Be careful to validate any information you are given as well as validating the software FEA results.

Attach you part here.

Valued Contributor
conklinjm
Posts: 63
Registered: ‎02-23-2009
Message 2 of 14 (934 Views)

Re: Stress Analysis

07-17-2012 04:34 PM in reply to: Jake_Clark/Alderon

Usually the graphical displacement model shown after the FEA analysis is extremely exaggerated; this is done so that you as the user can easily see what portion of your part or assembly is deflecting -- the values shown give the computed displacements based on your loading conditions.

As for the safety factor, the value indicates approximately how much more the part or assembly could be loaded before failure would occur. Depending on your industry and what might happen should your assembly fail, this value usually ranges from as low as 1.2 up to as high as 10. The higher the value -- the more uncertainty in the model, the material, and the loading or the more disastrous or costly (either in life-or-limb or in actual cost) should it fail.

HTH

*Expert Elite*
JDMather
Posts: 28,007
Registered: ‎04-20-2006
Message 3 of 14 (928 Views)

Re: Stress Analysis

07-17-2012 05:26 PM in reply to: conklinjm

conklinjm wrote:

... this value usually ranges from as low as 1.2 up to as high as 10. The higher the value -- the more uncertainty in the model...


Wrong.  Need to go back to school.

What book are you using to learn FEA?

 

Jake, your professor should be covering these topics in class - this is an advanced topic.

Search Amazon.com for Wasim Younis book.

Search http://au.autodesk.com for classes by Younis and others on FEA.

Go through the built in Help>Learning Tools>Tutorials

 

Be careful to validate any information you are given as well as validating the software FEA results.

Attach you part here.

Please mark this response as "Accept as Solution" if it answers your question.
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Active Member
Jake_Clark/Alderon
Posts: 6
Registered: ‎07-17-2012
Message 4 of 14 (903 Views)

Re: Stress Analysis

07-18-2012 06:07 AM in reply to: JDMather

We aren't going to learn stress testing for my degree. Mechanical Drafting and Design, a 2 year heavy CAD based program (I wish we were and i've told the professor we should). But I would like to know how to understand the stress test simulation cause I find if very helpful in finding out the abilities of my part.

 

I searched that mans name on Amazon and It came up with a few books, the first one being a stress simulation one. Is that all i need to help me understand a portion of it?

*Expert Elite*
JDMather
Posts: 28,007
Registered: ‎04-20-2006
Message 5 of 14 (889 Views)

Re: Stress Analysis

07-18-2012 09:03 AM in reply to: Jake_Clark/Alderon

Jake_Clark/Alderon wrote:

 Mechanical Drafting and Design, a 2 year heavy CAD based program (I wish we were and i've told the professor we should).


At my school FEA is not taught until the 3rd year - it would not be possible to do in a 2-yr program in a meaningful way in my opinion.

 

In the earlier Younis books he had both Dynamic Simulation and FEA in the same book.  In later editions (I think starting with Inventor 2012 he split this up into 2 books, one of FEA and one on Dynamic Simulation).

I recommend you get both, although for this problem you only need the FEA.

But go through the built in tutorials for FEA and Dynamic Simulation to see what is involved.

 

I teach basic FEA in Inventor, Algor (Autodesk Analysis), SolidWorks and Creo (Pro/E Mechanica) in one FEA class.

I teach Dynamic Simulation across two semesters in the Senior year and also use it in two other classes (Senior Projects and Senior Colloquium).

 


 

Please mark this response as "Accept as Solution" if it answers your question.
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Active Member
Jake_Clark/Alderon
Posts: 6
Registered: ‎07-17-2012
Message 6 of 14 (876 Views)

Re: Stress Analysis

07-18-2012 09:36 AM in reply to: Jake_Clark/Alderon

What institute do you teach at? (you can PM me if you'd like to answer that)

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JDMather
Posts: 28,007
Registered: ‎04-20-2006
Message 7 of 14 (860 Views)

Re: Stress Analysis

07-18-2012 12:02 PM in reply to: Jake_Clark/Alderon

2yr program   http://www.pct.edu/catalog/majors/CD.shtml#catalog_Curriculum  (will see extensive changes Fall 2013)

4yr program   http://www.pct.edu/catalog/majors/BCD.shtml#catalog_Curriculum

 

 

http://www.pct.edu/catalog/TransferringCredits.htm

Please mark this response as "Accept as Solution" if it answers your question.
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Distinguished Contributor
JimSteinmeyer
Posts: 326
Registered: ‎05-16-2011
Message 8 of 14 (840 Views)

Re: Stress Analysis

07-18-2012 02:54 PM in reply to: JDMather

Jake,

JD is absolutely correct in that ACCURATELY getting results requires more training than is available in a 2 year degree. Especially a drafting and CAD degree. ( I want to come back to this later) Stress evaluation requires more than plugging in some numbers and adding some forces. You need to understand where to place the forces and constraints, you need to have a good grasp on how to make the correct assumptions to generalize the loads to be able to enter them into the system, There are many "if this - then that" relations that you need to be able to predict to ensure you have all the forces. This is the conundrum with the plethora of FEA packages becoming easier to use in the CAD systems. It is now eiser than ever to enter some numbers and get "Pretty Pictures" that everyone can see. And if the pretty pictures look like you want (blue =good, red= bad) everyone will trust them and run with it. After all "The computer said it was good". However people are forgeting the old computer wisdom GI GO...garbage in garbage out.

     You seem inclined to want to go the extra step to ensure your work is right. If so I would suggest you follow JD's advice and pick up the suggested books. I suspect you will be wanting to use the simulation packages in the future and these texts will more than pay for themselves in making your work reliable if used.

     Now about the 2 year degree. I have a lot of respect for people who have them, in fact I have worked with many who after several years in the field deserve to be called engineers however I would strongly reccomend you get a 4 year degree. As one of my professors told one of my classmates who was going to change from the 4 to the 2 year degree, "You will make $15-$20,000 a year less and 95% of the time you will be doing the same work as the degreed engineer. The other 5% of the time he will know what book to find the information in."

Knowing where JD teaches and seeing the help he is able to provide would give me an idea which pprogram to attempt to get into as well. I wish I had had a professor who used something beyond hand calks and a DOS program to teach FEA. of course, doing those calcs on a stone tablet was a llittle difficult.

 

A little advice worth about as much as it cost you.

Thank you

Jim

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Active Member
Jake_Clark/Alderon
Posts: 6
Registered: ‎07-17-2012
Message 9 of 14 (812 Views)

Re: Stress Analysis

07-19-2012 05:57 AM in reply to: Jake_Clark/Alderon

Thanks Jim! I'm receiving one of the books today in the mail so I'll be looking into that book for sure. Is there any other books that are good? And I would go for a 4 year degree, and I was at ERAU, but it looks like JD's program would take most of my credits from my 2 year degree and I'm not sure I am able to do the 4 year degree at this time. It would be nice to.

 

Do you know of any online classes that could be available for me for this kind of thing?

Distinguished Contributor
JimSteinmeyer
Posts: 326
Registered: ‎05-16-2011
Message 10 of 14 (797 Views)

Re: Stress Analysis

07-19-2012 09:55 AM in reply to: Jake_Clark/Alderon

Jake,

Right now I have no idea what else is available out there. JD is far more involved with this type of thing than I am. After seeing the assistance he gives here I would give his program the priority.

As far as not being able to do 4 years now, you never know what you can do until pushed. I had a wife, 4 young kids, had just gone bankrupt on my farm, and hadn't done math beyond arithmatic in 12 years when I started Engineering school.

 

 

Jim

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