Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Visco-hyperelastic model
Posted Apr 5, 2013, 12:09 p.m. EDT Structural Mechanics Version 4.3a 0 Replies
Please login with a confirmed email address before reporting spam
I need to implement a viscoelastic material model in Comsol for a Stretch Blow Molding simulation.
The model is a modified Christensen-Yang Visco-Hyperelastic constitutive law.
It should be possible to implement it (basing on my limited knowledeges on the software). It should be easy to implement the hyperelastic part, but I have some doubts on the viscous part of the equation.
There is the Viscous part of the 2nd Piola Kirckhoff Stress tensor (Sv) with the equation:
Sv= Integral (from 0 to t)([M4+M5*I2(tau)]exp(-(t-tau)/M6)*Et(tau)dtau)
with M4, M5 and M6 model parameters, I2 second invariant of the Cauchy-Green tensor and Et the Strain rate tensor.
I know I have to use a PDE to evaluate the integral (transforming I=intergral(u*dt) in dI/dt=u) but I don't know how to specify the difference between t and tau. t is the time variable which is incremented after each iteration. But how do I insert the tau (the "material memory") since the inegral is in dtau?
Also, for what concern the strain rate tensor, can I simply create 6 variables and write d(E11,t), d(E22,t) ecc ecc?
Thank you very much
Regards
Hello Giampaolo Pileggi
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.