Viscoelasticity in Finite Deformation

[ryagh]

Dear Admin,

I need a few clarifications in the viscfd.f subroutine for the input and output variables and I will really appreciate if you could comment on them below:

1-tau(6): Is this 2nd Piola-Kirchhoff Stress at t_n?
2-sn(6): Is this Cauchy stress at t_n?
3-xj: Is this the element transformation Jacobian at the corresponding integration point?
4-hn(6,*): I do not know this matrix (the columns should correspond to different relaxation coefficients)

Thanks a lot!
RY

[Prof. R.L. Taylor]

1. tau is the Kirchhoff stress

2. sn is the second PK stress

3. xj is J = det(F)

4. hn(:,*) are internal variables for the integration algorithm. 

I believe this is based on the paper by Simo: CMAME v 60, pp 153ff.

[ryagh]

Thank you very much prof. Taylor, I found my answers for the model in the paper!