In subroutine ``uhardening.f'', the user can insert his own isotropic and/or kinematic hardening laws for (visco)plastic behavior governed by the keyword sequence *PLASTIC,HARDENING=USER. The header and variable description is as follows:
subroutine uhardening(amat,iel,iint,t1l,epini,ep,dtime,fiso,dfiso,
& fkin,dfkin)
!
! INPUT:
!
! amat: material name (maximum 80 characters)
! iel: element number
! iint: integration point number
! t1l: temperature at the end of the increment
! epini: equivalent irreversible strain at the start
! of the increment
! ep: present equivalent irreversible strain
! dtime: time increment
!
! OUTPUT:
!
! fiso: present isotropic hardening Von Mises stress
! dfiso: present isotropic hardening tangent (derivative
! of the Von Mises stress with respect to the
! equivalent irreversible strain)
! fkin: present kinematic hardening Von Mises stress
! dfkin: present kinematic hardening tangent (derivative
! of the Von Mises stress with respect to the
! equivalent irreversible strain)
!