Experimental Data Files for Various Polymers

thank you for this site and this Experimental Data

Dear All,

I would like to study the drop behaviour of Polypropylene at -30oC from a height of 1.2 m. I have two questions in my mind:

Q 1: Is the Johnson/Cook model is the right choice for my kind of application? I have seen many people using this model in their publications. But my concern is that is it good model for Polypropylene as it is thermoplastics? I have checked the material models from Abacus and in their matreial data base they say it is good for metals only. I can see in this model that it takes into consideration effects of strain rate, temperature and hardening.

Q2: What kind of tests I have to perfrom to get material data for my model: tensile, compression etc and at what temperature these tests have to be conducted? Is it possible that I perform my test at room temperature and at a particular strain rate and then enter this data and my model will take into consideration the variation of temperature and strain rates based upon my boundary conditions etc. I reallly donot understand how it works?

I would be thankful if anyone could write me about my matter.

Thanks very much

Best Regards

Shahid
Project officer at Swansea University UK

The Johnson-Cook model is sometimes used for impact simulations of PP, but there are other models that are more accurate (for example the Three Network Model link1, link2).

I recommend that you characterize your material at -30 deg C in uniaxial compression at different strain rates, and also perform a few tension tests at the same temperature.
It is not sufficient to test the material only at room temperature.

We have a great test lab and can help with the testing and material model calibration if you like.
Note that the MCalibration software can be used to quickly and easily calibrate the Johnson-Cook model (and other more advanced models).

-Jorgen

Thanks Jorgen for your informative reply.
Well, I am impresses with capability of the Mcalibration software. Its amazing.

Actually we here at Swansea University have equipped with standard testing machines for tensile and compression. I would not be able to persuade my line manager for doing that at your premises. Well, I would like to ask you in future about test specifications of standards specifications if you do not mind.

We here at Swansea University are working with Altair 11.0 based softwares. I am not sure how we can export parameters from Mcalibration to Hypercrash or Radioss etc which are the available softwares packages at Swansea University. Would you please comment on that before I talk to my manager about that?

I will be much interested to work with Mcalibration Software to extract the suitable parameters for Johnson-Cook Model for impact testing of PP at -30oC. Or alternatively I can also try using Three Network Model (TNM) for running my impact simulations. But keeping in mind our software packages what would you recommend?

Also would you please write me how you treat academia liscenses etc when you are quoting to some university etc?

I will be looking forward to hear from you. Please write or call me +44 7550 275355 if further information is needed. I will be happy to answer your queries.

Many thanks

I guess three net work model is not available in Abacus

I will respond with a private message.

-Jorgen

First of all, thanks for this data.
I want to use them to fit a model, but I have a problem regarding the strain measure:
For example: does -0.1 true strain in one axial compression mean a 10% compression of the specimen's initial length? And -0.7 a 70% compression respectively, which seems much to me.
I hope you can and will help me there. The main question is how to compute this true strain from geometrical data, for I have to define the deformation gradient for the fitting process.
Best regards, Lutz

A true strain of -0.1 means that:

ln(lambda) = -0.1,

where lambda = Lf / L0 = 1 + strain_eng.

Hence, strain_eng = exp(-0.1) - 1.0

-Jorgen

Hi Jorgen,

I am having a little trouble interpreting this data. Just now I am looking at PTFE tension_cyclic in word (won't open in excel). Firstly, should I be opening in a different program? If not, I have 3 columns:

The first column I have numbers going up in increments of 0.1
The second column all values are between 0 and -0.2 (ish)
The third all values less than -1

Could you explain what each of the columns represent?

Thanks in advance.

Column 1: time (s)
Column 2: true strain
Column 3: true stress (MPa)

-Jorgen

Thanks Jorgen.

One more comment: the data for the nitrile rubber was obtained in uniaxial compression at room temperature.