Linear elasticity is not used at all here. You can remove it from the material definition since nonlinear elasticity is already defined with keywords.
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I removed it in the keyword editor, but unfortunately the result is not better.
What am I doing wrong, I am really desperate. Have you ever tried to calculate that?
Can you show me your model tree, BSās etc. maybe some pictures? I hope you are calculated with PrePoMax, right?
Many thanks
Hi, wlh70
That wouldnāt be fair to some friends of mine that work designing this kind of pieces and that have invested a lot of money, effort, and hours by their own to master the software and understand the theory.
In case you want to keep trying I can confirm you Iām using Calculix as solver and PrePomax could solve it.
My model is axisymmetric to reduce the computation time. I have been able to translate and follow your referenced webpage from German and according to it the result is āokā to start (2.7% deviation) but as I comment Iām new with hyperelasticity and would probably need some adjustment.
The triky part is to translate the Shore to some consistent and usable C10, C01 and D1 constants. Itās all in the webpage.
None of the theory or model set up is easy so I recommend you search for some professional , at least to start. There are some in the forum really expertise with this kind of materials.
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It wonāt change the results because linear elasticity is just ignored here. Thereās just no need to use it and especially change any of its values as they will be ignored too.
First of all, thank you for helping with me here. I understand that you donāt want to reveal certain things here.
Creating Mooney coefficients is not that difficult. With sufficient accuracy, however, plausible results can also be obtained with literature values. The problem here is actually that a material law is not suitable for all calculation cases. In my example, Mooney works quite well up to 150% strain (according to my experience), then the stresses/forces become too small.
My problem is still that my force is not even close to the region of 2,500N, but is smaller by a factor of 100. I may have a problem with the input and definition in PrePoMax.
My intention is to produce usable and comprehensible results using simple examples. I can prove the whole thing at the end with a pressure test, because I can access it professionally and would also prepare the overall result and post it here.
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Thanks for pointing this out, I appreciate your support.
Ideally, you should enter test data and perform single-element tests using different hyperelastic material models to see which one best fits the whole range of the test. This procedure is automated in some software. Itās advised to use the Mooney-Rivlin model for moderate strains since it canāt catch the āupturnā occurring at larger loads. For limited data you should use the simplest models (having the lowe
Hi wlh70,
I have open your pmx file but you donāt have a history output for the overall reaction force. ĀæFrom where do you read the resultant force?
Your model alreaddy gives an acceptable value of 2668N compared to the reference provided in the German Webpage.?Āæ?
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Dear all,
many thanks for your support. I got it. The mistake was to forget the switch at totals to āYesā
Now I can fine tune and measure my real part and compare it to the FEA. That was now the hurdle I wanted to jump.
I will report more here soon about a pragmatic approach of initially simple rubber geometries. I know from my work as a product developer how complicated the design of e.g. rubber-metal components is, which have to be matched in all three spatial directions.
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