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What's the formula for the FFT spectrum?

User: "Altair Forum User"
Altair Employee
Updated by Altair Forum User

I want to create a 2D curve with the values of the first harmonic of TorqueElecMag(ROTOR)  to see how it changes with an I/O Parameter. Is that possible?

 

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    User: "asoualmi"
    Altair Employee
    Updated by asoualmi

    Hi,

    When you draw the curve of the torque, you can get the FFT of this curve. To do it:

    • Select the curve
    • Right click
    • Select Spectrum analysis (FFT)

    From this curve you get the first harmonic of the torque. And if you want of see the effect of I/O parameters you need to draw the FFT.

    Best regards.

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Thanks for answering..

    But I was wondering if theres a way to create a 2d curve with the first harmonic module on the Y axis and different values of an I/O parameter on the X axis.

     

    Right now I can do the fft spectrum separately for each value of the I/O parameter but I don't know how to do a 2d curve with the values I mentioned earlier.

    User: "asoualmi"
    Altair Employee
    Updated by asoualmi

    Hi,

    To get the first harmonic from a curve you can use this python script:

    print  Curve2d['SPECTRUM_V1'].y[0].values[0]

    Where :

    • SPECTRUM_V1' : the name of the FFT that you get from the 2D curve
    • y[0] : allows to select the amplitude
    • values[0] : allows to select the first harmonic

    To draw the curve, you can create an I/O parameter:

    b= Curve2d['SPECTRUM_V1'].y[0].values[0]

    print b

    lastInstance = VariationParameterFormula(name='First_harmonic',

                              formula=str(b))

     

    Hope this will help.

    Best regards.