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## hardening.

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 20 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)
    !