9.5.5 User-supplied

DIANA offers the user-supplied subroutine mechanism to specify a general nonlinear material behavior for reinforcements. The user-supplied material model USRMAT is available for both embedded reinforcements BAR and GRID.

• The user-supplied material model should be coded with great care. The routine should perform the intended function without influencing other parts of DIANA. See Volume Analysis Procedures for the precautionary measures to be taken when applying user-supplied subroutines.

• The user-supplied material model should be developed and tested on a single element example to verify if the routine models the constitutive behavior accurately before using the subroutine in production analyses.

The following information from table 'MATERI' is passed to the user-supplied subroutine USRMAT [§11.4.2].

    (syntax)

USRMAT

specifies that a general material model is determined via user-supplied subroutine USRMAT. The keyword usrmod may be used as a switch in the subroutine. This gives you the opportunity to code various material models in one single subroutine.

USRVAL

usrval is a series of material parameters. These parameters cannot be modified in the subroutine.

USRSTA

usrsta are the initial values of a series of internal state variables. These variables may be used and modified in the subroutine.

USRIND

usrind are the initial values of a series of integer indicator variables. These variables may be used and modified in the subroutine.

    (file.dat)

'MATERI'
    2  YOUNG   200000.0
       USRMAT  SATURA
       USRVAL  600.0 1.0  0.0 1250.0 0.05
       USRSTA  0.0 0.0 0.0
'END'

In addition to the data for for the user-supplied subroutine, this example also inputs the value for the Young's modulus E . This value is necessary for the preliminary linear analysis. If you need this value in the user-supplied subroutine, then you can take them from the FILOS file via a special access routine GTC [Vol. Analysis Procedures].

For an embedded BAR, the user-supplied material model describes a uniaxial stress-strain model. For an embedded GRID, the user-supplied material model describes two uncoupled uniaxial stress-strain relationships for the two axis directions of the grid.