How to calculate multiplicative decomposition F=FeFp

[Ren]

Dear  FEAP users,

    I want to make the FEAP user material subroutine , but I have no idea how to achieve the multiplicative decomposition F=FeFp.

   Sain has achieve it in his paper Constitutive modeling of ice in the high strain rate regime. International Journal of Solids & Structures, 2011, 48(5):817-827.

    I thank you in advance!

Best,
RW Liu

[FEAP_Admin]

Here are two good references that explain the algorithmic implementation:

J.C. Simo, Numerical analysis and simulation of plasticity, in Handbook of Numerical Analysis Vol VI, Edited by P.G. Ciarlet and J.L. Lions, 1998.

J.C. Simo, Algorithms for static and dynamic multiplicative plasticity that preserves the classical return mapping schemes of the infinitesimal theory, Comp. Meth. Appl. Mech. Engng., v99, 61-112, (1992).

[Ren]

Dear professor，
   
   Thanks for your apply . I would try to get the solution from book by J.C. Simo .

Best Regards,

RW Liu

[Ren]

Dear professor，
   
  I have read the book named Numerical Analysis and Simulation of Plasticity by J.C. Simo . But the algorithm for elastoplastic model of multiplicative plasticity in finite strain plasticity is incomplete, since the multiplicative factorization is lack of uniqueness or invariance as mentioned in this book.

  Could you please give me more advice and guidance about how to achieve the algorithm for F=FeFp at finite strains?

Best Regards,

RW Liu

[FEAP_Admin]

There is nothing wrong with the model/algorithm in the book.  Dr. Simo just points out the obvious point of the indeterminacy of the intermediate configuration.  If you are in the isotropic case, it does not matter, you never have to worry about it.  In the anisotropic case, you just have to pick one of the many Ansatzs that are available in the literature for the plastic spin -- choose the one that makes the most physical sense for your problem.

[Ren]

Dear professor，
   
   I am grateful for your apply . I would try my best to understand the algorithm in the book by Dr. Simo.

Best Regards,

RW Liu

[Yaakov]

Dear FEAP Administrator,

I want to completely understand the subrotine "plasfd.f", which is based on the book "J.C. Simo, Numerical analysis and simulation of plasticity"

Could you tell me, where are numerical algorithms part for code line "390 - 395 in Sub. plastfd.f"  in this book?

I am grateful for your reply!

Kind regards,
Yaakov

[FEAP_Admin]

Which version of the code are you looking at?  Maybe easier to just copy and past those six lines.

[Prof. R.L. Taylor]

This routine was developed from

author    = {F. Auricchio and R.L. Taylor},
title     = {A return-map algorithm for general associative isotropic
elasto-plastic materials in large deformation regimes},
journal   = {Int. J. Plasticity},
volume    = {15},
year      = {1999},
pages     = {1359--1378} }

[Yaakov]

Dear Prof. Taylor and FEAP Administrator,

Many thanks for your support, I will carefully read this article.

Code: [Select]

          do a = 1, 3
            do b = 1, 3
              tres(a,b) = fss(a,b) + d_el
            end do ! b
            tres(a,a) = tres(a,a) + G2inv
          end do ! a

Kind regards,
Yaakov

[Ren]

Dear Prof. Taylor and FEAP Administrator,

I have studied carefully on the masterpiece book Computational Inelasticity by Simo,  by now I have debugged my subroutine for many times. But it still does not work well. So I am wondering that if there is any subroutine within FEAP using the multiplicative decomposition. I will appreciate it if you can give me some advice.

Thank you in advance.

Renwei

[Prof. S. Govindjee]

Have a look in elements/material/finite/plasfd.f

[Ren]

Dear Prof. Govindjee,

Thank you for your reply and guidance.

I check my download file and open the elements/material file in Visual Studio 2017, but I fail to find ../finite/plasfd.f. I also try to find this subroutine using the 'Find and Replace' function, but I did not find it.

Could you please give me further instruction to find elements/material/finite/plasfd.f?

I am looking forward to your reply.

Renwei

[FEAP_Admin]

Please ask someone in your lab that knows how to navigate the file system on your type of computer.

[Ren]

Thank you for your reply.

I am the first one to try to learn FEAP in our team. I will teach them when I master it.

Thanks.
Renwei