Experimental Techniques

[pa.selvadurai]

Hi:

I am testing some natural rubber. I am getting what seems to be good results but noticed that in the data for natural rubber on this website (http://polymerfem.com/index.php?pageid=mat_mod&material=8) the test were done at: ISOTHERMAL and QUASI-STATIC conditions. I am positive I am doing Isothermal (I have a thrmocouple set up beside the experiment) but how can I ensure that the experiment is Quasi-static (i.e. what is the correct strain rate?)?

Also, my results look quite perculiar. Although the inflections points and general graph features look like the natural rubber tested but Dr. Jorgen Bergstrom. I am getting approx 1MPa of ENGstress for 1.0 ENGstrain (almost linear). Anyone know if this is common in natural gum rubber?

Thanks

[Jorgen]

First note that the term "quasi-static" simply means that inertial effects can be ignored.

The experimental data provided on the web page you mentioned were obtained at "equilibrium", which corresponds to an infinitely slow strain rate. This type of data is useful for calibrating a hyperelastic material model, but not a viscoelastic model.

- Jorgen