FEA 64 bit problem

[ing]

We have recently switch from XP to win7. Basically 32 to 64 bit. The simulation results in the 32bit vertion of inventor has always been second to none. But the new (new to us) 64 bit vertion has yeiled some false results. more worriingly the results indicate that the model is in fact good enough to do the job. I have attached a document outlining my findings.

 

I have contacted my software supplier and they reported it to autodesk. Autodesk has in turn said that the problem is noted but the case has been closed.  I have no problem accepting a minor deviation, even 5% but the results can have an error of 0% to 80%.

 

If anyone knows a cure or has had this type of trouble, please let me know.

[cwhetten]

Thank you for posting your analysis.  The results are very disturbing.  We will have to exercise extreme caution when using the simulation module.

Cameron Whetten
Inventor 2014

[ing]

I have conducted more comparison simulations on inventor 2014 64 bit and inventor 2012 32 bit. here are some screenshots of my simulations. 

Inventor 2012 von mis:

Inventor 2014 von mis:

The expected stress at this location is 37 Ksi. This stress value was calculated via the traditional method. This means that the new inventor is wrong by 36%!!! The simulations are identical. it is the same model, same material and the same forces and constrains. It is bizzare that I am the first to report this problem. if you are have a simmilar issure please post it on this thread. I will be adding some more examples later on.

[blair]

Unbelievable!

[ing]

I have done some more analysis comparisons. Below is an analysis performed in Inventor 2012:

And here is the exact same analysis on Inventor 2014:

[ing]

Even small analysis are yeilding false results!!! This one is 3x3 square tubing with some plates on it.

Inventor 2012:

and now Inventor 2014:

From 30.44 Ksi to 17.43 for the exact same analysis, almost half. anyone else has this problem!?

[ing]

If there were any doubts this one will clear them up! This is the worst one to date.

Inventor 2012:

Inventor 2014:

The 2012 vertion gave us a max of 88.77ksi. The 2014 vertion gave us 0.12ksi...... with the EXACT same model. I simply ran the simulation in 2012 and then re-ran it in 2014. Thats an error of 99.8%. Please autosesk... make a patch for the analysis enviroment. The worst part is that Inventor used to school Solid Works in the analysis department.

[blair]

I thought we could elevate this to Support for them to look at it.

[GSE_Dan_A]

This scares the bejeezus out of me (and I am sure many others). I suppose it is a good thing to NEVER take the results at face value. It is good practice to always make a prediction of where the stresses should occur and how the members will deform (compression, tension, bending, etc...)

[JDMather]

It would be useful to have the actual part files that these results are taken from.

[bob_holland]

We have confirmed this as an issue and are working to resolve it ASAP.

At this time there is no known workaround.

If someone has one please post it.

Thank you.

[Al_RItchie]

'An issue' ? I'd say so! Here's hoping you guys can get to the bottom of it pretty sharpish.

[ing]

Thank you Bob for confiming that Autodesk is working to resolve the issue. If you need any models or more information, I would be happy to help.

P.S. I installed Inventor 2014 32 bit on an XP computer and the results are still not correct. I originally thought that the 64 bit was the problem but it seems that it is not.

[Ray_Feiler]

This data set was created in Inventor Pro 2014. Because I do not have access to Inventor Pro 2012, can someone STEP out the assembly and run a simulation to compare the results?

My attachments are missing, what is the size limit?

I can't add the attachments, the zipped file sizes are now all under 1 meg. What's up with that?

[Ray_Feiler]

Lets try this link out. http://a360.co/1fSePeQ

This is my first time using Autodesk 360 so let me know if this works. All IPT files are in a rolled up state and just ignore the missing content center folder message if you get it. All needed files should be there.

[Ray_Feiler]

Here is a Autodesk 360 link to the full report.

http://a360.co/1dTt6XC

[ing]

Hello Ray,

Can you performe a pack and go on your assembly and upload it again. This will give me all of your simulation data.

[ing]

I see that your strurcure is frame generated. If you use the Frame analysis tool, you can acheave accurate results. you will not see stress concentrations but it will give you a good enough picture to see if the stresses add up compared to the other analysis. I have verified that the frame analysis is correct.

[Ray_Feiler]

Thank you for taking a look and the tip.