Viscoelastic fatigue?

[cmc123]

Hi,

I am fairly new to this type of analysis and before I get to the fatigue part have an FEA model to deal with first! I am looking to do this with various grades of PTFE, ETFE etc.

But my query is that I realise there is no widely used/ accepted models for viscoelastic fatigue (please correct me if wrong!). If I only need to concern myself with low temperature (less than glass transition), can I ignore the viscous part and just consider the elastic properties of the material and use an elastic fatigue model?

Thanks in advance.

[Jorgen]

You can certainly try that - it is a reasonable first step.
Note that PTFE can undergo significant creep/stress relaxation so it usually better to use a non-linear viscoplastic material model (such as the DNF model (http://polymerfem.com/content.php?10-PolyUMod)).

-Jorgen