User-Defined Thermal Material

The MATUSHT Bulk Data Entry, in combination with the LOADLIB I/O Option Entry, allows for the definition of thermal material through user-defined external functions.

The external functions may be written in Fortran, C or C++. The resulting libraries and files should be accessible by OptiStruct regardless of the coding language, provided that consistent function prototyping is respected, and adequate compiling and linking options are used.

Note: User-defined Thermal Material Heat Transfer is currently only supported for Nonlinear Transient Heat Transfer Analysis.

Write External Functions

Subroutine:

subroutine usrmatht(idu, matID, ieuid, 
				Integration_Point, Layer, Simpson_Point,	
Stater, State,
 nState, drot, props, nprops, temp, 
 dtemp, kinc, dt, t_step, t_total, hgen, smat
 userdata, ierr)

      character*32000 userdata

integer*8 i, idu, matID, ieuid, nState, nprops, kinc, ierr
integer Integration_Point, Layer, Simpson_Point
      double precision Stater(nState), State(nState)
      double precision drot(3,3), rmat(nprops)
      double precision etempmat, dtemp, dt, t_step, t_total
      double precision hgen, smat(9)

initusr subroutine:

subroutine initusr(idu,nstate,cstate)
      implicit none
      integer idu,nstate
      character*64 cstate(nstate)

The strings in the initusr subroutine should always be declared as follows:

      character*64 cstate(nstate)

The declaration should always use 64-character size.

After declaration, the cstate variable can be assigned the label to print in the user-defined results with 1 being the index for the first variable in the example below:

	cstate(1) = “Variable Name for State(1)”

Note: Subroutine names should not be changed.

Subroutine Arguments

The following table briefly describes the arguments which are passed among OptiStruct and the external subroutines.


Argument	Type	Input / Output	Description
`idu`	integer	Input	This is defined via the `USUBID` parameter on the MATUSHT Bulk Data Entry. This argument can be used to define and choose between different types of materials within the same user subroutine. optional use
`matID`	Integer	Input	Material ID.
`ieuid`	integer	Input	Element ID.
`Integration_Point`	Integer	Input	Gauss Integration Point.
`Layer`	Integer	Input	Laminate Layer.
`Simpson Point`	Integer	Input	Through-thickness Simpson Integration Point.
`drot(3,3)`	Double (table)	Input	Transformation matrix.
`props`	double (table)	Input	This table contains all the user-defined thermal material property information from the `PROPERTY` continuation line of the MATUSHT entry.
`nprops`	Integer	Input	This is the total number of thermal material properties defined on the `PROPERTY` continuation line of the MATUSHT entry.
`temp`	double	Input	This is the temperature at the end of the current increment.
`dtemp`	double	Input	This is the temperature increment of the current increment.
`kinc`	integer	Input	Current nonlinear increment.
`dt`	double	Input	Current time step increment
`t_step`	double	Input	Current subcase time of the current time step.
`t_total`	double	Input	Total time (if IC is used). This is effective when the IC case control entry of a nonlinear transient thermal subcase points to a previous nonlinear transient thermal subcase.
`Stater`	double (table)	Input	Table of State variables at the last converged time-step. They are constant between iterations of the same time step.
`State`	double (table)	Input/Output	Table of State variables at the current time-step. They are updated and passed between iterations of the same time-step. State variables are variables that can be requested as output in the H3D file. Any variable calculated within the solution process in the subroutine can be output by defining it as a state variable.
`nState`	integer	Input	Number of State Variables that the user requires in the subroutine. See `Stater` for more information.
`cstate`	string	Output	A character-based label from `initusr` subroutine to OptiStruct. In the `usermaterial` or `smatusr` subroutines the state variables can be assigned user-defined labels which can be displayed in the H3D file when imported in HyperView. The `cstate` variable provides the name for the state variable declared in the subroutines to display in the H3D file.
`hgen`	double (table)	Output	Generated heat.
`smat`	Double (table)	Output	Material matrix. These are calculated during the solution and are output to OptiStruct. Format for smat matrix is provided below. `smat(1): KXX Thermal Conductivity smat(2): KXY Thermal Conductivity smat(3): KXZ Thermal Conductivity smat(4): KYY Thermal Conductivity smat(5): KYZ Thermal Conductivity smat(6): KZZ Thermal Conductivity smat(7): CP Heat Capacity per unit mass smat(8): RHO Density smat(9): Free Convection Heat Transfer Coefficient (Unused).`
`userdata`	Character	Output	User-defined message that is output based on the value of `ierr` argument.
`ierr`	Integer	Input/Output	Flag that activates/deactivates Output message for an OptiStruct run from the user subroutine. 0 (Default) No action. 1 The OptiStruct run errors out and an ERROR message is printed based on the message defined in `userdata` argument. -1 The information message defined in `userdata` argument is printed and the OptiStruct run continues.

Output

Regular Built-in OptiStruct output, like Grid Temperatures, Element Fluxes, and so on can be requested for any thermal material user-subroutine based model. Additionally, user-defined output can also be requested via the State(*) variable in the user-subroutine. The number of such State(*) variables should be identified on the NDEPVAR field.

This State variable can be assigned to any output variable that is required to be output from the subroutine, and it can then be visualized in HyperView after loading the H3D file.

Build External Libraries for User-defined Materials

You can build shared libraries on Windows or Linux.

Refer to Build External Libraries for more information.