The user subroutine ``creep.f'' is made available to allow the user to incorporate his own creep law by selecting the keyword sequence *CREEP,LAW=USER in the input deck. The creep routine must return the creep rate and its derivative with respect to the Von Mises stress for a given Von Mises stress. The header and a description of the input and output variables is as follows:
subroutine creep(decra,deswa,statev,serd,ec,esw,p,qtild,
& temp,dtemp,predef,dpred,time,dtime,cmname,leximp,lend,
& coords,nstatv,noel,npt,layer,kspt,kstep,kinc)
!
! user creep routine
!
! INPUT:
!
! decra(1) material name
! statev(1..nstatv) internal variables
! serd not used
! ec(1) equivalent creep at the start of the increment
! ec(2) not used
! esw(1..2) not used
! p not used
! qtild von Mises stress
! temp temperature at the end of the increment
! dtemp not used
! predef not used
! dpred not used
! time(1) value of the step time at the end of the increment
! time(2) value of the total time at the end of the increment
! dtime time increment
! cmname material name
! leximp not used
! lend not used
! coords(1..3) coordinates of the current integration point
! nstatv number of internal variables
! noel element number
! npt integration point number
! layer not used
! kspt not used
! kstep not used
! kinc not used
!
!
! OUTPUT:
!
! decra(1) equivalent deviatoric creep strain increment
! decra(2..4) not used
! decra(5) derivative of the equivalent deviatoric
! creep strain increment w.r.t. the von Mises
! stress
! deswa(1..5) not used