changed restriction of dTstar, its now based on the residuum, if it does not improve 0.5*dTstar is used instead
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Franz Roters
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a5f49a0578
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85df3b95ee
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@ -203,6 +203,7 @@
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if (t == CPFEM_dt) exit ! reached final "then"
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else ! solution not found
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i = i+1_pInt ! inc cutback counter
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! write(6,*) 'ncut:', i
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if (i > nCutback) then ! limit exceeded?
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write(6,*) 'cutback limit --> '//msg
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write(6,*) 'Grain: ',grain
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@ -344,8 +345,8 @@
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character(len=*) msg
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integer(pInt) cp_en, CPFEM_in, grain
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integer(pInt) iState,iStress,dummy, i,j,k,l,m
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real(pReal) dt,det, max_E, p_hydro
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real(pReal), dimension(6) :: Tstar_v,dTstar_v,Rstress, E, T_elastic
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real(pReal) dt,det, p_hydro
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real(pReal), dimension(6) :: Tstar_v,dTstar_v,Rstress, E, T_elastic, Rstress_old
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real(pReal), dimension(6,6) :: C_66,Jacobi,invJacobi
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real(pReal), dimension(3,3) :: Fg_new,Fp_old,Fp_new,Fe_new,invFp_old,invFp_new,Lp,A,B,AB
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real(pReal), dimension(3,3,3,3) :: dLp, LTL
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@ -368,15 +369,9 @@
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if (all(state_new == 0.0_pReal)) state_new = state_old
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RstateS = state_new
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iState = 0_pInt
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! elastic guess for small Tstar, however reduced to prec_max_e
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if (all(Tstar_v < 0.1_pReal)) then
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E = math_Mandel33to6(A-math_I3)
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max_E = maxval(E)
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if (max_E > prec_max_e) E = prec_max_e * E / max_E
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Tstar_v = 0.5_pReal*matmul(C_66, E)
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endif
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! QUESTION follow former plastic slope to guess better?
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Rstress = Tstar_v
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Rstress_old=Rstress
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state: do ! outer iteration: state
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iState = iState+1
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@ -395,13 +390,20 @@ stress: do ! inner iteration: stress
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forall(i=1:3) Tstar_v(i)=Tstar_v(i)-p_hydro
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call constitutive_LpAndItsTangent(Lp,dLp, Tstar_v,state_new,grain,CPFEM_in,cp_en)
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B = math_I3-dt*Lp
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! B = B / math_det3x3(B)**(1.0_pReal/3.0_pReal)
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! B = B / math_det3x3(B)**(1.0_pReal/3.0_pReal)
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AB = matmul(A,B)
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T_elastic= 0.5_pReal*matmul(C_66,math_Mandel33to6(matmul(transpose(B),AB)-math_I3))
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p_hydro=(T_elastic(1)+T_elastic(2)+T_elastic(3))/3.0_pReal
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forall(i=1:3) T_elastic(i)=T_elastic(i)-p_hydro
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Rstress = Tstar_v - T_elastic
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if (maxval(abs(Tstar_v)) == 0.0_pReal .or. maxval(abs(Rstress/maxval(abs(Tstar_v)))) < tol_Stress) exit stress
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! step size control: if residuum does not improve redo iteration with reduced step size
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if(maxval(abs(Rstress)) > maxval(abs(Rstress_old)) .and. iStress > 1) then
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! write(6,*) 'Hallo', iStress
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Tstar_v=Tstar_v+0.5*dTstar_v
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dTstar_v=0.5*dTstar_v
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cycle
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endif
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if (iStress > 1 .and. (maxval(abs(Tstar_v)) < 1.0e-3_pReal .or. maxval(abs(Rstress/maxval(abs(Tstar_v)))) < tol_Stress)) exit stress
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! update stress guess using inverse of dRes/dTstar (Newton--Raphson)
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LTL = 0.0_pReal
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@ -410,8 +412,7 @@ stress: do ! inner iteration: stress
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do k=1,3
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do l=1,3
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do m=1,3
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! LTL(i,j,k,l) = LTL(i,j,k,l) + AB(i,m)*dLp(m,j,k,l) + AB(j,m)*dLp(m,i,l,k) ! old
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LTL(i,j,k,l) = LTL(i,j,k,l) + dLp(j,i,m,k)*AB(m,l) + AB(m,i)*dLp(m,j,k,l) ! new (and correct??)
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LTL(i,j,k,l) = LTL(i,j,k,l) + dLp(j,i,m,k)*AB(m,l) + AB(m,i)*dLp(m,j,k,l)
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enddo
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enddo
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enddo
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@ -430,14 +431,12 @@ stress: do ! inner iteration: stress
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return
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endif
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dTstar_v = matmul(invJacobi,Rstress) ! correction to Tstar
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! limit correction of Tstar
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if(maxval(abs(dTstar_v)) > crite*maxval(abs(Tstar_v))) &
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dTstar_v=dTstar_v*crite*maxval(abs(Tstar_v))/maxval(abs(dTstar_v))
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Rstress_old=Rstress
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Tstar_v = Tstar_v-dTstar_v
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! write(999,*) Tstar_v, dTstar_v, Rstress
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enddo stress
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! write(6,*) 'istress', istress
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Tstar_v = 0.5_pReal*matmul(C_66,math_Mandel33to6(matmul(transpose(B),AB)-math_I3))
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dstate = dt*constitutive_dotState(Tstar_v,state_new,grain,CPFEM_in,cp_en) ! evolution of microstructure
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Rstate = state_new - (state_old+dstate)
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RstateS = 0.0_pReal
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@ -448,6 +447,8 @@ stress: do ! inner iteration: stress
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enddo state
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! write(6,*) 'istate', istate
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! write(999,*) 'Tstar_v raus', Tstar_v
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! write(999,*)
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invFp_new = matmul(invFp_old,B)
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call math_invert3x3(invFp_new,Fp_new,det,failed)
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@ -21,12 +21,11 @@
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! *** Convergence criteria for outer (state variables) loop ***
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real(pReal), parameter :: tol_State = 1.0e-6_pReal
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! *** Maximum number of iterations in inner (stress) loop ***
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integer(pInt), parameter :: nStress = 100_pInt
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integer(pInt), parameter :: nStress = 500_pInt
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! *** Convergence criteria for inner (stress) loop ***
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real(pReal), parameter :: tol_Stress = 1.0e-6_pReal
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! *** Factor for maximum stress correction in inner (stress) loop ***
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real(pReal), parameter :: crite = 0.1_pReal
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! *** Maximum strain used in elastic guess in inner (stress) loop ***
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real(pReal), parameter :: prec_max_e = 1.0e-3_pReal
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! real(pReal), parameter :: crite = 0.1_pReal
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END MODULE prec
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