Learning Forum

[pavan_m240846ce]

After compiling the umat code and using it, the mesh deformation is not visible in the post processing. this is the code which I replaced in the subroutine umat 41. It is just not showing the deformation but there is change in the resultant velocity at nodes. What may the reason and how to fix this.

 subroutine umat41 (cm,eps,sig,epsp,hsv,dt1,capa,etype,tt,
     & temper,failel,cma,qmat,elsiz,idele,reject)

      include 'nlqparm'
      include 'bk06.inc'
      include 'iounits.inc'

      dimension cm(*),eps(*),sig(*),hsv(*),cma(*),qmat(3,3)
      logical failel,reject
      character*5 etype
      integer*8 idele

c ===============================
c LOCAL VARIABLES
c ===============================

      real*8 Kmod,Gmod,sig_t,phi,coh,alpha,beta
      real*8 Kmod_d,Gmod_d
      real*8 eps_v,eps_cr,Cd,D
      real*8 e1,e2,e3
      real*8 I1,J2,s1,s2,s3
      real*8 phi_r,dp_a,dp_k,f,scale
      real*8 tiny

      tiny = 1.0d-20

c ===============================
c MATERIAL PARAMETERS FROM CARD
c ===============================

      Kmod  = cm(1)
      Gmod  = cm(2)
      sig_t = cm(3)
      phi   = cm(4)
      coh   = cm(5)
      alpha = cm(6)
      beta  = cm(7)

c ===============================
c ONLY FOR SOLID TYPE ELEMENTS
c ===============================

      if (etype.eq.'solid'.or.etype.eq.'sph  '.or.
     &    etype.eq.'sldax'.or.etype.eq.'sld2d') then

      if (.not.failel) then

c ===============================
c VOLUMETRIC STRAIN
c ===============================

      eps_v = eps(1)+eps(2)+eps(3)

c ===============================
c CRITICAL TENSILE STRAIN
c (using bulk modulus relation)
c ===============================

      eps_cr = sig_t/(3.d0*Kmod + tiny)

c ===============================
c DAMAGE EVOLUTION
c ===============================

      if (eps_v.gt.eps_cr) then
         Cd = alpha*(eps_v-eps_cr)**beta
      else
         Cd = 0.d0
      endif

      D = 1.d0 - dexp(-Cd)

c ===============================
c DEGRADED STIFFNESS
c ===============================

      Kmod_d = (1.d0-D)*Kmod
      Gmod_d = (1.d0-D)*Gmod

c ===============================
c DEVIATORIC STRAIN
c ===============================

      e1 = eps(1)-eps_v/3.d0
      e2 = eps(2)-eps_v/3.d0
      e3 = eps(3)-eps_v/3.d0

c ===============================
c ELASTIC STRESS UPDATE
c ===============================

      sig(1)=sig(1)+Kmod_d*eps_v+2.d0*Gmod_d*e1
      sig(2)=sig(2)+Kmod_d*eps_v+2.d0*Gmod_d*e2
      sig(3)=sig(3)+Kmod_d*eps_v+2.d0*Gmod_d*e3
      sig(4)=sig(4)+Gmod_d*eps(4)
      sig(5)=sig(5)+Gmod_d*eps(5)
      sig(6)=sig(6)+Gmod_d*eps(6)

c ===============================
c DRUCKER-PRAGER YIELD CHECK
c ===============================

      I1 = sig(1)+sig(2)+sig(3)

      s1 = sig(1)-I1/3.d0
      s2 = sig(2)-I1/3.d0
      s3 = sig(3)-I1/3.d0

      J2 = 0.5d0*(s1*s1+s2*s2+s3*s3)
     &     +sig(4)*sig(4)+sig(5)*sig(5)+sig(6)*sig(6)

      phi_r = phi*3.14159265358979d0/180.d0

      dp_a = 2.d0*dsin(phi_r)/(dsqrt(3.d0)*(3.d0-dsin(phi_r)))
      dp_k = 6.d0*coh*dcos(phi_r)/(dsqrt(3.d0)*(3.d0-dsin(phi_r)))

      f = dsqrt(J2 + tiny)-3.d0*dp_a*I1-dp_k

c ===============================
c RADIAL RETURN (STABLE)
c ===============================

      if (f.gt.0.d0) then

         scale = (3.d0*dp_a*I1+dp_k)/(dsqrt(J2)+tiny)

         sig(1)=sig(1)*scale
         sig(2)=sig(2)*scale
         sig(3)=sig(3)*scale
         sig(4)=sig(4)*scale
         sig(5)=sig(5)*scale
         sig(6)=sig(6)*scale

      endif

      endif
      endif

      return
      end. 

[ErKo]

 

Hi

Debugging of UMAT is outside the scope of the help Ansys employees can provide here.

 

Please wait though for other forum members (D Chen), that have experience with UMATS to chime in perhaps and provide feedback.

 

Thank you for your understanding, and all the best

Erko