Experimental Curve fitting tool . Hyperelastic models

disla

Hi, have recently being searching for some free curve fitting tool for different Hyper elastic models.
The more interesting ones I have found are :

https://welsim.com/products/#curvefitter (seems to work fine as far as I have tested)



https://fileexchange.scilab.org/toolboxes/350000 (Not tested yet. Only three material models. Needs Scilab installation)

I have also ear about OptiMax but seems too complicated for me.
¿I would appreciate if someone knows some free tool for the experimental data adjustment?

Regards

Sergio

I have used sucesfully Prepomax for the determination of Mooney Rivling coefficients from a rubber part, based on compression test of the part, not from standard samples.

disla

Thank you, Sergio,

I sent to you a private message.
These two graphs compare how a well-known commercial software and the free curve Fit tool adjust a given set of experimental data. Not bad at all... In fact, it looks slightly better to me. The only problem is that it is closed and I don't really know what is he doing. There is not too much information about the algorithms involved neither.

JohnM

We use Optimax, and it works well. We use a load cell machine (Lloyd) to obtain a load deflection curve. This test setup gets modeled in Mecway, and the C01 C10 coefficients are made variables (I think we go straight to the CCX deck at this point). I will admit that this is usually "intern work", so we sort of re-learn the method at the beginning of every summer . Optimax is pretty useful, worth pushing past the initial learning curve.

disla

Thanks, JohnM and Sergio. Developers comment to me they are using the nonlinear Levenberg-Marquardt algorithm. Not much more information about it.

-K. Levenberg, "A method for the solution of certain non-linear problems in least squares", Quart. Appl. Math. 2 (1944), 164-168.
-D. W. Marquardt, "An algorithm for least squares estimation of non-linear parameters", SI A MJ. Appl. Math. 11 (1963), 431-441.

3rav

Hi,

Have you tried GNUPLOT?

like:
fit f(x) 'data.txt' via C10, C01, C20, C02 ,C11

disla

No, I haven't try it. I will take a look.
Thanks 3Rav.

reynotrent

A good example of AI is https://labdeck.com/ai-models/ and Curve Fitting tool https://labdeck.com/curve-fitting/:
Additionally, you can create AI Curve Fitting apps with a drug and drop Python GUI designer at
https://labdeck.com/python-designer/python-gui-designer/ which will automatically make the code for a Python GUI instead.

standardsapplied

Hi Disla,

Take a look at our free online nonlinear curve fitting calculator at: https://standardsapplied.com/nonlinear-curve-fitting-calculator.html

Our nonlinear curve fitting tool uses the Levenberg-Marquardt that you mentioned and has 72 functions built in.

Overwrite / Paste your data into the data field and press run. The calculator will try fitting all 72 built-in functions, sorting by the least error and the plotting the result. You can quickly click through to see how the other fictions did.

If there is a missing function that you'd like us to add, please let us know!!

There is also a list of great software to try on our website too, if we missed any excellent packages, let us know and we'll add it! -looks like we missed Gnuplot, I'll add that right now, I know that comes highly recommended.

disla

Thank you Raynotrent and standardsapplied. Nice!! . We have now a lot of options.