The INTERP function returns the iord derivative of the interpolated value of SPLINE/id at time=x. The INTERP function supports time-series splines, which are splines that include a FILE argument that specifies a time history file of type DAC or RPC III.
Format
INTERP (Indep_Var, Method, Spline_name, Deriv_order)
Arguments
Independent Variable | Enter a real variable that specifies the value of time, the independent variable along the x-axis of the time series spline that is being interpolated. |
Derivative Order | Select the order of the derivative that Adams Solver takes at the interpolated point, and then returns through INTERP. ■Curve Coordinates (0) - Take no derivative (default) ■1st Derivative (1) ■2nd Derivative (2) |
Interpolation Method | Select the method of interpolation: ■Linear (1) ■Cubic (3) |
Spline Name | Enter the name of the SPLINE statement in the Adams Solver dataset. The SPLINE statement must reference time series data from a DAC or RPC III file. |
Examples
As part of the Adams Durability feature, the INTERP function lets you specify how you want to interpolate spline data from an RPC III or DAC time history file. An example is shown below of how to specify the INTERP function in Adams Solver for durability analysis.
For durability analysis, the INTERP function appears in a motion or force statement, and looks as follows:
INTERP(time, 3, spline id)
where:
■time is the independent variable of the interpolation. For durability analysis, this real variable is always time or an expression that includes time.
■3 is the method of interpolation, which indicates cubic interpolation between data points. 1, which indicates linear interpolation, is also a valid entry.
For more information on the INTERP function, see INTERP for Adams Solver (C++) or INTERP for Adams Solver (FORTRAN).