Creep (creep.f)

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 input/output depends on the kind of material: if the elastic properties of the material are isotropic, the Von Mises stress goes in and the equivalent deviatoric creep strain increment and its derivative with respect to the Von Mises stress for a given Von Mises stress come out. If the elastic properties of the material are anisotropic, the equivalent deviatoric creep strain increment goes in and the Von Mises stress and the derivative of the equivalent deviatoric creep strain increment with respect to the Von Mises stress come out. The creep regime is, however, always isotropic. Whether the elastic regime is isotropic or anisotropic is triggered by the value of the variable lend.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 (general): ! ! 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 ! 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 if = 2: isotropic creep ! if = 3: anisotropic creep ! 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 ! ! INPUT only for elastic isotropic materials: ! qtild von Mises stress ! ! INPUT only for elastic anisotropic materials: ! decra(1) equivalent deviatoric creep strain increment ! ! ! OUTPUT (general): ! ! 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 ! ! OUTPUT only for elastic isotropic materials: ! decra(1) equivalent deviatoric creep strain increment ! ! OUTPUT only for elastic anisotropic materials: ! qtild von Mises stress !