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#1 2020-08-19 14:12:47

Duc Vu
Registered: 2020-04-03
Posts: 20

Contact friction fIber/matrix doesn't work

Hello everyone,

I'm simulating the pull out process of an inclined steel fiber from the matrix cementitious and I would like to evaluate the spalling size of matrix near the exit point.
The mesh is compound of a fiber mesh (HEX27) and matrix mesh (TRIAG4), I used FORMULATION='CONTINUE' and ALGO_CONT = 'PENALISATION' to model the friction on the interface following the instruction in the documentation and in J-P.Aubry's  book, the code ran but the result i got were stranged:
   The stress is too small (about 10^-9 MPa) in the fiber and be zero in the matrix.
   Plotting with Paravis showed that the fiber passed through the matrix and not be bended at all.
   I played with the COEF_PENA_FROT but nothing changed.
Otherwise, I tried with 2 meshes separated and assembled them with ASSE_MAILLAGE -> SUPERPOSE and used LIAISON_MAIL then I got the error

Problème : la matrice est singulière ou presque singulière :
  Lors de la factorisation de la matrice, on a rencontré un problème
  (pivot nul ou presque nul) à la ligne 29654 qui correspond au degré de liberté donné ci-dessus

Anybody can help me to find out what is the matter with my command and I have also some more question:
1. Which is better between the separated mesh and compound mesh in term of evaluating the friction with STAT_NON_LIN?
2. Is there any rule or recommendation for the value of COEF_PENA_FROT? I've read the document u4.44.11 but it is not clear.

Here attached my .mess and .comm files, the mesh files are in the link :
(remove the ())

pullout_messcomm.zip, Size: 12.61 KiB, Downloads: 20