Linear calculation results interpretation

Infos zur Ergebnisinterpretation, Darstellung und Auswertung /
Info about results, visualisation and evaluation

Moderatoren: ccad, mz15, auroraIco, Lehrstuhl

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Racime
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Beiträge: 16
Registriert: Fr 9. Mai 2014, 16:38

Linear calculation results interpretation

Beitrag von Racime »

Now i got some results form my analysis however i have some difficulties to interpret these. I made the same analysi in Algor to verifiy if the results are rougly the same. It is not possible for me to see any correlation between the results of ALgor and Z88 aurora. I have created a rod fixed in a plate (plate 100x100x20mm) the rod is Ø30mm With a length of 500mm. The force on the rod end is 500N the plate i fully fixed on the end.

This results in a Nice calculation, but since the results are not in Mpa or N/mm2 i don't know what i am realy looking at. Algor gives a Von mises of 99Mpa With a displacement of 2,7mm this is a Clear answer. how do interpret the results.

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SHautsch
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Beiträge: 380
Registriert: Mo 15. Apr 2013, 11:03

Re: Linear calculation results interpretation

Beitrag von SHautsch »

Dear Racime,

unfortunately it's nearly impossible to help you if you don't attach your project files or at least a screenshot of the postprocessor. I don't know much about Algor, but if you use the same type of elements, number of elements and same boundary conditions, for a linear static analysis there shouldn't be great differences.

The results are calculated in the unit which you used during preprocessing, because FEA usually does not use units (for example: you put in mm, N and N/mm^2, you will get displacements in mm, forces in N and stresses in N/mm^2).

Please send us your project files or a screenshot of your problem and we will help!

Kind regards,
S. Hautsch

Racime
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Registriert: Fr 9. Mai 2014, 16:38

Re: Linear calculation results interpretation

Beitrag von Racime »

I will take a look at the input data. Did send a zip file to you to check.

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SHautsch
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Registriert: Mo 15. Apr 2013, 11:03

Re: Linear calculation results interpretation

Beitrag von SHautsch »

Dear Racime,

unfortunately I can't open your project because the structure is too big (8819067 elements / 1444758 nodes).
I have taken a look at your STEP file and it seems that it's not really necessary to use so much elements.
A quick test showed that around 13000 elements worked fine, but to compare your results with ALGOR I would need the exact same boundary conditions which you applied on your structure.
Your project files didn't include any information about the material, boundary conditions and there were no results, this project has never been calculated with Z88Aurora.

Kind regards,
SHautsch

Racime
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Registriert: Fr 9. Mai 2014, 16:38

Re: Linear calculation results interpretation

Beitrag von Racime »

Hmmm, that is strange. The model was calculated by Z88 i'm sure i sent the correct model. Will check again.

Racime
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Registriert: Fr 9. Mai 2014, 16:38

Re: Linear calculation results interpretation

Beitrag von Racime »

Tried to send the model once more including the results. I expected a stress on the elements of about 130Mpa, but the results lie somewhere around 2,6E+3 (2600). This is a bit high and i'm sure it has to do With the fact that i'm not quite sure on the way the program Works. :roll: . The stresses on the model look ok to me only a bit high.

i did not include the amount of element willingly :oops: . The boundry conditions are not complicated. the Object is fixed on a square plate and a force is placed on the end of the rod that is Connected to the plate. I can expect som difference, but this is a bit too much i think so i suspect my lack of exerience With Z88 is the problem here.

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SHautsch
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Registriert: Mo 15. Apr 2013, 11:03

Re: Linear calculation results interpretation

Beitrag von SHautsch »

Dear Racime,

your project arrived here. Unfortunately the material is missing, because you added a new material to your material database, which is stored locally.
I calculated your model with construction steel (young's modulus 210000 N/mm^2) and I get max. displacement of 72.4 mm and max. stress of 2510 N/mm^2.

Is it correct that the force is applied in x direction, at right angle to your rod?
You chose force (uniformly distributed), which applies the same force to every node, in your case 500 N per node! Maybe this is not what you wanted and what is causing the problems.

If you choose surface load, the 500 N will be distributed to the nodes in your set. I did a quick analysis with surface load and I get max. displacement of 2.19 mm and max. stress of 76 N/mm^2 (at the nodes) or 84.5 N/mm^2 (at Gauss points). This seems much better and quite similar to ALGORs results.

Kind regards,
SHautsch

Racime
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Registriert: Fr 9. Mai 2014, 16:38

Re: Linear calculation results interpretation

Beitrag von Racime »

You helped me out here. :-).

I thought i distributed the load on the surface (as i'm used to in Algor). but now i understand that will put in several 500N loads on the end of the rod. The results are then quite correct using your standard material. The Von mises stress from Algor is 90,01Mpa. This is very close to the result from Z88, so now i know how i can work with the case. Thank you for you patience. :)

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SHautsch
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Beiträge: 380
Registriert: Mo 15. Apr 2013, 11:03

Re: Linear calculation results interpretation

Beitrag von SHautsch »

No problem at all, I'm glad I could help you with your problem.

Feel free to ask again if something doesn't work as expected.

Kind regards,
SHautsch

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