Dear all,
I would like to know if anyone can help me on how to Calculate Phan-Thien-Tanner (PTT) constitutive model parameters from rheology experimental data. I need those parameter for an ANSYS polyflow simulation of die swell. I have experimental viscosity curve for PLA at 200C.
Thanks
The first thing you have to define is what variant of the Phan-Thien-Tanner model you want/should use. The choice will be dictated by the response of the flow-curve and material functions available from rheometers experimentally (either shear-thinning, strain softnening and/or hardening, the response of the first normal-stress difference in shear, etc.). You should best match the response provided by the model-variant to your experimental data. When that's defined, calculation to fit the parameters of the model can be done.
See our paper below where there are two PTT model-variants (LPTT and EPTT; there are other variants) and their response:
López-Aguilar, J. E., Webster, M. F., Tamaddon-Jahromi, H. R., & Manero, O. (2015). Journal of Non-Newtonian Fluid Mechanics, 222(C), 190–208. http://doi.org/10.1016/j.jnnfm.2014.11.008
If you have ANSYS POLYMAT, it is not difficult to perform the data adjustment and get the parameters for the PTT model.
Check the following link.
https://dl.tufts.edu/downloads/0c483w59v?filename=wh2475173.pdf
And there is a tutorial about uploading experimental data and performing the data fitting in POLYMAT; unfortunately, it is in Spanish, but I'm sure you can follow it.
https://www.youtube.com/watch?v=_S3gDDulbGg
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