Moony-Rivlin Constants

[carlpop]

I need to model a rubber material in Marc;where can I find some general Moony-Rivlin constants for rubber?

 

[cloche]

It depends heavily on the rubber! I have the same problem with a part in NBR-70: for the moment, the only info I got is uniaxial compression test data found at

http://www.polymerfem.com

Based on real data, you can use best-fit interpolation to get M-R (or any other constitutive law) coefficients.

 

[RvL04]

May I suggest getting actual testing data of your material as an option? Generic published lists with data of materials comparable to yours often have you end up with a material model showing unrealistic values. If you just do a google search for 'hyperelastic testing' you should be able to find some labs who do this. In most cases these test labs work together with the software vendor (in this case MSC.Marc) so that the data can be integrated into your model directly.

 

[baris23]

Im looking for nbr and viton material test datas too. I also checked polymerfem but there is only uniaxial compression test datas for the materials and when i apply these on Msc.Marc i got not very good results..
i would be greatful if you help me..

 

[RvL04]

well, that' doesn't surprise me, baris, because like I said, published data lists make my skin itch... they're fine if you want to use them to get some general idea of the material properties, but if you are using data to build a model, it simply isn't good enough. Especially if the data is only in one state of strain (in this case, uniaxial compression), you can't expect a model to run with such a limited amount of information. Really, try to get some material properties of the actual material you are studying by having it tested. Plenty of labs out there can do a very good job in testing in several states of strain, like uniaxial tension, planar shear, equal biaxial tension (avoiding the ugly, rich-in-friction uniaxial compression data), it's well worth spending a little bit of money and time getting this data now, because it'll save you a LOT of time later!

Ron

 

[craigmj]

Santoprene has published some hyperelastic material model constants if you are just looking for something to plug in. Try Grade: 111-45.

http://www.santoprene.com/cgi-bin/resource_library/product_grade.pl

Look under 'FEA data'

Depending on what you are trying to accomplish I would be careful about using any online material properties. Youre better off to test exactly what you are using.

CJ