/FUNCT_PYTHON

Block Format Keyword Defines a function defined with Python script.

Format


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/FUNCT_PYTHON/`fct_ID`
def `function_name`(`argument`)
…Python code…
return `variable`

Blank line after the “return” is mandatory


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Blank line

Definition


Field	Contents	SI Unit Example
`fct_ID`	Function identifier.
`function_name`	Function name. Must be unique in the model. (Text)
`argument`	(Mandatory) Argument of the function. (Text)
`variable`	(Mandatory) Output variable. (Text)

Radioss Variables

The Python script can use global, nodal or elementary data from Radioss.

Table 1. Global Variables
key	Definition
`TIME`	Current simulation time.
`DT`	Current time step.

Table 2. Nodal Variables
key	Definition
`Ci(node_ID)`	Coordinate $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`Di(node_ID)`	Displacement $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`Vi(node_ID)`	Translational velocity $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`Ai(node_ID)`	Translational acceleration $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`VRi(node_ID)`	Rotational velocity $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`ARi(node_ID)`	Rotational acceleration $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.
`DRi(node_ID)`	Rotation $i \in \{X, Y, Z\}$ of `node_ID` in the global coordinate system.

Table 3. Shell or Solid Element Variables (same key as /H3D/SHELL or /H3D/SOLID)
key	Definition
`ALPHA(ELEM_ID)`	Shear angle alpha of material /MAT/LAW58 in degrees for the element `ELEM_ID`.
`AMS(ELEM_ID)`	Elements using AMS timestep due to /DT/CST_AMS for the element `ELEM_ID`.
`BFRAC(ELEM_ID)`	Burn fraction of the element `ELEM_ID`.
`BULK(ELEM_ID)`	Artificial viscosity of the element `ELEM_ID`.
`COLOR(ELEM_ID)`	Volume fraction color of the element `ELEM_ID`.
`DAMi(ELEM_ID)`	Principal damage values in local cracking skew direction $i \in \{1, 2, 3\}$ for the element `ELEM_ID`.
`DAMA(ELEM_ID)`	Maximum damage over time of all /FAIL criteria for the element `ELEM_ID`.
`DAMG(ELEM_ID)`	Mean damage over thickness integration points (only for coupled damage models) for the element `ELEM_ID`.
`DAMINI(ELEM_ID)`	Maximum damage initiation variable among all failure criteria using initiation variable before computing stress softening (/FAIL/INIEVO) for the element `ELEM_ID`.
`DENS(ELEM_ID)`	Density for the element `ELEM_ID`.
`DOMAIN(ELEM_ID)`	SPMD domain number of an element for the element `ELEM_ID`.
`DT(ELEM_ID)`	Element timestep for the element `ELEM_ID`.
`EINT(ELEM_ID)`	Element internal energy per unit volume for the element `ELEM_ID`.
`EINTM(ELEM_ID)`	Specific internal energy for the element `ELEM_ID`.
`EINTV(ELEM_ID)`	Internal energy density for the element `ELEM_ID`.
`ENER(ELEM_ID)`	Specific energy density (internal energy divided by the element mass) for the element `ELEM_ID`.
`ENTH(ELEM_ID)`	Enthalpy for the element `ELEM_ID`.
`ENTHM(ELEM_ID)`	Massic enthalpy for the element `ELEM_ID`.
`ENTHV(ELEM_ID)`	Enthalpy density for the element `ELEM_ID`.
`EPSD(ELEM_ID)`	Equivalent strain rate for the element `ELEM_ID`.
`EPSP(ELEM_ID)`	Plastic strain for the element `ELEM_ID`.
`FAIL(ELEM_ID)`	Number of failed layers for the element `ELEM_ID`.
`FAILURE(ELEM_ID)`	Damage of a specific failure criterion references by its optional identifier `fail_ID` for the element `ELEM_ID`.
`FILL(ELEM_ID)`	Filling percentage for the element `ELEM_ID`.
`FLDF(ELEM_ID)`	FLD damage factor indicator for the FLD failure model of the element `ELEM_ID`.
`FLDZ(ELEM_ID)`	FLD failure zone factor for the FLD failure model of the element `ELEM_ID`.
`GROUP(ELEM_ID)`	Internal group identifier of the element `ELEM_ID`.
`HC_DSSE_F(ELEM_ID)`	HC_DSSE damage factor indicator of the element `ELEM_ID`.
`HC_DSSE_Z(ELEM_ID)`	HC_DSSE failure zone factor for the HC_DSSE failure model of the element `ELEM_ID`.
`HOURGLASS(ELEM_ID)`	Hourglass energy per mass unit of the element `ELEM_ID`.
`K(ELEM_ID)`	Specific for turbulent energy in CFD of the element `ELEM_ID`.
`MACH(ELEM_ID)`	Mach number of the element `ELEM_ID`.
`MASS(ELEM_ID)`	Element mass of the element `ELEM_ID`
`MOMi(ELEM_ID)`	Cell momentum Density in direction $i \in \{X, Y, Z, X Y, Y Z, Z X\}$ for FVM with Interface TYPE22 of the element `ELEM_ID`.
`NL_EPSD(ELEM_ID)`	Non-local plastic strain rate of the element `ELEM_ID`.
`NL_EPSP(ELEM_ID)`	Non-local plastic strain of the element `ELEM_ID`.
`NXTF(ELEM_ID)`	Instability factor of /FAIL/NXT failure model of the element `ELEM_ID`.
`OFF(ELEM_ID)`	Status of the element `ELEM_ID`.
`P(ELEM_ID)`	Pressure of the element `ELEM_ID`.
`PHI(ELEM_ID)`	Angle between the element system and direction 1 orthotropy of the element `ELEM_ID`.
`SCHLIEREN(ELEM_ID)`	Schlieren image of the element `ELEM_ID`.
`SIGEQ(ELEM_ID)`	Equivalent stress based on a material’s yield criteria of the element `ELEM_ID`.
`SIGi(ELEM_ID)`	Stress $i \in \{X, Y, Z, X Y, Y Z, Z X\}$ in specified direction of the element `ELEM_ID`.
`SSP(ELEM_ID)`	Sound speed of the element `ELEM_ID`.
`TDEL(ELEM_ID)`	Time at which element `ELEM_ID` is deleted.
`TDET(ELEM_ID)`	Detonation time of the element `ELEM_ID`.
`TEMP(ELEM_ID)`	Temperature of the element `ELEM_ID`.
`THICK(ELEM_ID)`	Thickness of the element `ELEM_ID`.
`THIN(ELEM_ID)`	% thinning for shell of the element `ELEM_ID`.
`TILLOTSON(ELEM_ID)`	Region identifier for Tillotson Equation of State of the element `ELEM_ID`.
`TSAIWU(ELEM_ID)`	Tsai-Wu criterion for material of the element `ELEM_ID`.
`TVIS(ELEM_ID)`	Specific for turbulent viscosity in CFD of the element `ELEM_ID`.
`VDAMi(ELEM_ID)`	Value of damage $i \in \{1, 2, 3\}$ for /FAIL/SNCONNECT of the element `ELEM_ID`.
`VELi(ELEM_ID)`	Cell velocity $i \in \{X, Y, Z, X Y, Y Z, Z X\}$ for FVM with Interface TYPE22 of the element `ELEM_ID`.
`VFRAC1(ELEM_ID)`	Volumetric fraction $i \in \{1, 2, 3, 4\}$ of the element `ELEM_ID`.
`VOLU(ELEM_ID)`	Volume of the element `ELEM_ID`.
`VONM(ELEM_ID)`	von Mises stress of the element `ELEM_ID`.
`VORT(ELEM_ID)`	Vorticity resultant for ALE material of the element `ELEM_ID`.
`VORTi(ELEM_ID)`	Vorticity in direction $i \in \{X, Y, Z\}$ for ALE material of the element `ELEM_ID`.

Example (Using `TIME`)

Sinus function using TIME

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/FUNCT_PYTHON/1
def disp_X(x):
    import math

    X = TIME
    Y = 10*math.sin(X*20*math.pi)
    return Y

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Example (/FUNCT_SMOOTH)

Same function as /FUNCT_SMOOTH

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT_PYTHON/1
def smooth_interpolation(x):
    X = [0.0 ,  1.00000E-02]
    Y = [0.0 , -1.33000E+02]
    N = len(X)
# Return Y[0] if x is less than the smallest X
    if (x < X[0]):
        return Y[0]
# Return Y[N-1] if x is greater than the largest X
    if (x > X[-1]):
        return Y[-1]
# Find the interval where X[i] <= x < X[i+1]
    for i in range(N - 1):
        if (X[i] <= x < X[i + 1]):
            d = (x - X[i]) / (X[i + 1] - X[i])
            return Y[i] + (Y[i + 1] - Y[i]) * d * d * d * (10 - 15 * d + 6 * d * d)
# In case x is exactly X[N-1]
    return Y[-1]

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Example (Nodal)

Sample using nodal information

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/FUNCT_PYTHON/1
def velocity(x):

    pos_X = CX(1)
    vel_X = VX(1)
#
    if (pos_X > 100):
        Y = -2000.0
    elif (pos_X < 1):
        Y = 2000.0
    else:
        Y = vel_X
    return Y

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Comments

The empty line after the “return” is mandatory.
A function and a table cannot share the same identifier.
This function can be used with these options: /IMPDISP, /IMPVEL, /IMPACC, /IMPDISP/FGEO, /IMPVEL/FGEO, /IMPVEL/LAGMUL, /IMPTEMP, /CLOAD, /PLOAD, /GRAV, and /IMPFLUX.
The number of lines in a function is limited to 1000. But it is possible to break a function into multiple functions, since it is possible to call a Python function from another Python function.
Radioss variables are in “read only” mode from python.
Python values will always be in double precision.
The returned value will be 0.0 if the result is there with no data for the requested Radioss variable and element ELEM_ID.
Radioss uses the Python library available in the HyperWorks installation. It is possible to use a different Python distribution by setting the environment variable RAD_PYTHON_PATH.
The option “-python” must be added to the Starter command line to confirm that you want to explicitly use a python script with Radioss.