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Initial conditions, Type=state variables

*Initial conditions, Type=state variables , <option>
<element set>, <ic parameter 1>, ..., <ic parameter n>
Specify the initial values of arbitrary state variables (needed by more advanced constitutive models) at the integration points of an element or element set. Use one of the following options:

  • Default Use this option to specify the initial <value> of an arbitrary state variable <state variable name> of an element set <element set name> previously used to define a solid Section. This is required since the solid Section is used instead of an element set to assign a (mechanical) material to elements. The command line takes the following form:

    *Initial Conditions, Type = state variables, default
    <element set name>, <state variable name>, <value>

  • User

    Use this option to specify the use of a user defined subroutine to define the initial value of arbitrary state variables described further here.

    *Initial Conditions, Type = state variables, user
    <element set name>

  • Fluctuation

    Use this option to specify the a spatially fluctuating but correlated distribution using Markov's algorithm in an isotropic fashion. A range of the state variable has to be defined using <value max> and <value min>. In addition, a <correlation length> has to be given, which defines the zone of which values are correlated. The correlation length should be at least larger than the distances of integration points in order to be active. The correlation length has the unit of length.

    *Initial Conditions, Type = state variables, fluctuation
    <element set name>, <state variable name>, <value max>, <value min>, <correlation length>

    figure 1 Figure 1. Effect of <correlation length> in defining a spatially fluctuating initial field of void_ratio being the void ratio used by the constitutive model variants

    The influence of <correlation length> is demonstrated in Fig. 1. The following definition was used to generate the last field:

    *Initial Conditions, Type = state variables, fluctuation
    soil_box, void_ratio, 0.9, 0.6, 0.005

    Note that the elements have a size of only 0.002 m in this model for why the value of the correlation length is rather low.