VUEXPAN

User subroutine to define thermal strain increments.

User subroutine VUEXPAN:

can be used to define thermal strain increments as a function of temperature, time, element number, predefined field variables, etc.;
will be called at all integration points of the elements for which the material contains user-defined thermal expansion; and
is intended for models in which the thermal strains depend on temperature, time, state variables, and/or predefined fields in complex ways.

This page discusses:

User Subroutine Interface
Variables to Be Defined
Variables Passed in for Information

ProductsAbaqus/Explicit

User Subroutine Interface

      subroutine vuexpan (
C Read only (unmodifiable)variables -
     * nblock, nDir, nShr, nExpanType,
     * nElem, nIntPt, nLayer, nSectPt,
     * stepTime, totalTime, dt, cmname, 
     * nstatev, nfieldv, nprops, props,
     * tempOld, tempNew, fieldOld, fieldNew,
     * stateOld, 
C Write only (modifiable) variable -
     * stateNew, strainThInc, dStrainTherDT )
C
      include 'vaba_param.inc'
C
      dimension strainThInc(nblock,nDir+nShr),
     * dStrainTherDT(nblock,nDir+nShr),
     * nElem(nblock), props(nprops),
     * tempOld(nblock), tempNew(nblock),
     * fieldOld(nblock,nfieldv),
     * fieldNew(nblock,nfieldv),
     * stateOld(nblock,nstatev),
     * stateNew(nblock,nstatev)
C
      character*80 cmname
C
      do 100 km = 1, nblock
        user coding to define strainThInc, dStrainTherDT,
        and, optionally, stateNew
  100 continue

      return
      end

Variables to Be Defined

strainThInc(nblock,nDir+nShr)

Increments of thermal strain. The number of values to be defined and the order in which they are arranged depend on the type of thermal expansion being defined.

For isotropic expansion give the isotropic thermal strain increment as the first and only component of the matrix.
For orthotropic expansion give $Δ ϵ_{11}^{t h}$ , $Δ ϵ_{22}^{t h}$ , and $Δ ϵ_{33}^{t h}$ as the first, second, and third components of the matrix, respectively.
For anisotropic expansion give $Δ ϵ_{11}^{t h}$ , $Δ ϵ_{22}^{t h}$ , $Δ ϵ_{33}^{t h}$ , $Δ ϵ_{12}^{t h}$ , $Δ ϵ_{23}^{t h}$ , and $Δ ϵ_{13}^{t h}$ . Direct components are stored first, followed by shear components in the order presented here. For plane stress only three components of the matrix are needed; give $Δ ϵ_{11}^{t h}$ , $Δ ϵ_{22}^{t h}$ , and $Δ ϵ_{12}^{t h}$ as the first, second, and third components, respectively.

dStrainTherDT(nblock,nDir+nShr)

Variation of thermal strains with respect to temperature, $\partial ϵ^{t h} / \partial θ$ . The number of values and the order in which they are arranged depend on the type of thermal expansion being defined.

For isotropic expansion give the variation of the isotropic thermal strain with respect to temperature as the first and only component of the matrix.
For orthotropic expansion give $\partial ϵ_{11}^{t h} / \partial θ$ , $\partial ϵ_{22}^{t h} / \partial θ$ , and $\partial ϵ_{33}^{t h} / \partial θ$ as the first, second, and third components of the matrix, respectively.
For anisotropic expansion give $\partial ϵ_{11}^{t h} / \partial θ$ , $\partial ϵ_{22}^{t h} / \partial θ$ , $\partial ϵ_{33}^{t h} / \partial θ$ , $\partial ϵ_{12}^{t h} / \partial θ$ , $\partial ϵ_{23}^{t h} / \partial θ$ , and $\partial ϵ_{13}^{t h} / \partial θ$ . Direct components are stored first, followed by shear components in the order presented here. For plane stress only three components of the matrix are needed; give $\partial ϵ_{11}^{t h} / \partial θ$ , $\partial ϵ_{22}^{t h} / \partial θ$ , and $\partial ϵ_{12}^{t h} / \partial θ$ as the first, second, and third components, respectively.

stateNew(nblock,nstatev)

Values of state variables at each material point at the end of the increment.

Variables Passed in for Information

nblock: Number of points to be processed in this call to VUEXPAN.
nDir: Number of direct components in a symmetric tensor.
nShr: Number of indirect components in a symmetric tensor.
nExpansionType: The thermal expansion type: 1 for isotropic expansion, 2 for orthotropic expansion, and 3 for anisotropic expansion.
nElem(nblock): User-defined element number.
nInt: Integration point number.
nLayer: Layer number.
nSectPt: Section point number in the current layer.
stepTime: Value of time since the step began.
totalTime: Value of total time. The time at the beginning of step is given by totalTime - stepTime.
dt: Time increment size.
cmname: User-specified material name, left justified. It is passed in as an uppercase character string. Some internal material models are given names starting with the "ABQ_" character string. To avoid a conflict, you should not use "ABQ_" as the leading string for cmname.
nstatev: Number of user-defined state variables that are associated with this material.
nfieldv: Number of user-defined external field variables.
nprops: User-specified number of user-defined thermal expansion properties.
props(nprops): User-supplied thermal expansion properties.
tempOld(nblock): Temperatures at each material point at the beginning of the increment.
tempNew(nblock): Temperatures at each material point at the end of the increment.
fieldOld(nblock,nfieldv): Values of user-defined field variables at each material point at the beginning of the increment.
fieldNew(nblock,nfieldv): Values of user-defined field variables at each material point at the end of the increment.
stateOld(nblock,nstatev): Values of state variables at each material point at the beginning of the increment.