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22.214.171.124 The data-fit model
The data-fit model tries to fit predicted FE data to a user-defined data curve of time-value pairs. The data curve usually represents some experimentally obtained result, e.g. reaction force, as a function of time. The data-fit model needs a data source, i.e. a function for extracting the model data, and the data curve.
<Objective type="data-fit"> <fnc type="[enter type]"> ... </fnc> <data> <pt>0, 0</pt> ... <pt>1, 1</pt> </data> </Objective>
The data source is defined by the type attribute of the fnc tag. There are currently two supported values.
- parameter: The function will track the time evolution of a model parameter.
- filter_positive_only: Another data source is needed to extract model data (e.g. parameter), but only positive values are returned. If the model parameter's value was negative, zero will be returned by the function.
In the case of parameter, a child element defines the parameter that will act as the data source for the objective function.
<fnc type="parameter"> <param name="fem.rigidbody('rigid').Fz"/> </fnc>
This defines the data function as a function of time. You can also change the ordinate of the function to create other functional dependencies. For example, the following creates a load-displacement curve for a rigid body.
<fnc type="parameter"> <ordinate name="fem.rigidbody('rigid').position.x"/> <param name="fem.rigidbody('rigid').Fz"/> </fnc>