umat_user.f File Reference

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Functions/Subroutines
subroutine	umat_user (amat, iel, iint, kode, elconloc, emec, emec0, beta, xokl, voj, xkl, vj, ithermal, t1l, dtime, time, ttime, icmd, ielas, mi, nstate_, xstateini, xstate, stre, stiff, iorien, pgauss, orab, pnewdt, ipkon)

Function/Subroutine Documentation

umat_user()

subroutine umat_user	(	character*80	amat,
		integer	iel,
		integer	iint,
		integer	kode,
		real*8, dimension(*)	elconloc,
		real*8, dimension(6)	emec,
		real*8, dimension(6)	emec0,
		real*8, dimension(6)	beta,
		real*8, dimension(3,3)	xokl,
		real*8	voj,
		real*8, dimension(3,3)	xkl,
		real*8	vj,
		integer	ithermal,
		real*8	t1l,
		real*8	dtime,
		real*8	time,
		real*8	ttime,
		integer	icmd,
		integer	ielas,
		integer, dimension(*)	mi,
		integer	nstate_,
		real*8, dimension(nstate_,mi(1),*)	xstateini,
		real*8, dimension(nstate_,mi(1),*)	xstate,
		real*8, dimension(6)	stre,
		real*8, dimension(21)	stiff,
		integer	iorien,
		real*8, dimension(3)	pgauss,
		real*8, dimension(7,*)	orab,
		real*8	pnewdt,
		integer, dimension(*)	ipkon
	)

!
!     calculates stiffness and stresses for a user defined material
!     law
!
!     icmd=3: calcutates stress at mechanical strain
!     else: calculates stress at mechanical strain and the stiffness
!           matrix
!
!     INPUT:
!
!     amat               material name
!     iel                element number
!     iint               integration point number
!
!     kode               material type (-100-#of constants entered
!                        under *USER MATERIAL): can be used for materials
!                        with varying number of constants
!
!     elconloc(*)        user defined constants defined by the keyword
!                        card *USER MATERIAL (actual # =
!                        -kode-100), interpolated for the
!                        actual temperature t1l
!
!     emec(6)            Lagrange mechanical strain tensor (component order:
!                        11,22,33,12,13,23) at the end of the increment
!                        (thermal strains are subtracted)
!     emec0(6)           Lagrange mechanical strain tensor at the start of the
!                        increment (thermal strains are subtracted)
!     beta(6)            residual stress tensor (the stress entered under
!                        the keyword *INITIAL CONDITIONS,TYPE=STRESS)
!
!     xokl(3,3)          deformation gradient at the start of the increment
!     voj                Jacobian at the start of the increment
!     xkl(3,3)           deformation gradient at the end of the increment
!     vj                 Jacobian at the end of the increment
!
!     ithermal           0: no thermal effects are taken into account
!                        >0: thermal effects are taken into account (triggered
!                        by the keyword *INITIAL CONDITIONS,TYPE=TEMPERATURE)
!     t1l                temperature at the end of the increment
!     dtime              time length of the increment
!     time               step time at the end of the current increment
!     ttime              total time at the start of the current step
!
!     icmd               not equal to 3: calculate stress and stiffness
!                        3: calculate only stress
!     ielas              0: no elastic iteration: irreversible effects
!                        are allowed
!                        1: elastic iteration, i.e. no irreversible
!                           deformation allowed
!
!     mi(1)              max. # of integration points per element in the
!                        model
!     nstate_            max. # of state variables in the model
!
!     xstateini(nstate_,mi(1),# of elements)
!                        state variables at the start of the increment
!     xstate(nstate_,mi(1),# of elements)
!                        state variables at the end of the increment
!
!     stre(6)            Piola-Kirchhoff stress of the second kind
!                        at the start of the increment
!
!     iorien             number of the local coordinate axis system
!                        in the integration point at stake (takes the value
!                        0 if no local system applies)
!     pgauss(3)          global coordinates of the integration point
!     orab(7,*)          description of all local coordinate systems.
!                        If a local coordinate system applies the global 
!                        tensors can be obtained by premultiplying the local
!                        tensors with skl(3,3). skl is  determined by calling
!                        the subroutine transformatrix: 
!                        call transformatrix(orab(1,iorien),pgauss,skl)
!
!
!     OUTPUT:
!
!     xstate(nstate_,mi(1),# of elements)
!                        updated state variables at the end of the increment
!     stre(6)            Piola-Kirchhoff stress of the second kind at the
!                        end of the increment
!     stiff(21):         consistent tangent stiffness matrix in the material
!                        frame of reference at the end of the increment. In
!                        other words: the derivative of the PK2 stress with
!                        respect to the Lagrangian strain tensor. The matrix
!                        is supposed to be symmetric, only the upper half is
!                        to be given in the same order as for a fully
!                        anisotropic elastic material (*ELASTIC,TYPE=ANISO).
!                        Notice that the matrix is an integral part of the 
!                        fourth order material tensor, i.e. the Voigt notation
!                        is not used.
!     pnewdt             to be specified by the user if the material
!                        routine is unable to return the stiffness matrix
!                        and/or the stress due to divergence within the
!                        routine. pnewdt is the factor by which the time
!                        increment is to be multiplied in the next
!                        trial and should exceed zero but be less than 1.
!                        Default is -1 indicating that the user routine
!                        has converged.
!     ipkon(*)           ipkon(iel) points towards the position in field
!                        kon prior to the first node of the element's
!                        topology. If ipkon(iel) is smaller than 0, the 
!                        element is not used.
!
      implicit none
!
      character*80 amat
!
      integer ithermal,icmd,kode,ielas,iel,iint,nstate_,mi(*),iorien,
     &  ipkon(*)
!
      real*8 elconloc(*),stiff(21),emec(6),emec0(6),beta(6),stre(6),
     &  vj,t1l,dtime,xkl(3,3),xokl(3,3),voj,pgauss(3),orab(7,*),
     &  time,ttime,pnewdt
!
      real*8 xstate(nstate_,mi(1),*),xstateini(nstate_,mi(1),*)
!
!     insert here code to calculate the stresses
!
      if(icmd.ne.3) then
!
!        insert here code to calculate the stiffness matrix
!
      endif
!
      return