Visco elastic material using loss factor and storage module

Hi all,

I need to use a visco elastic materail in my analysis and already have the data for loss factor and storage module vs frequency. I have been reading that is necessary to use prony-series to us it, but i don't know exaclty how.

Thanks

Comments

  • jjdoylejjdoyle PittsburghMember

    If you have experimental viscoelastic data in frequency domain (i.e. frequency dependent storage and loss moduli), this can be used to calculate prony coefficients in time domain using MAPDL curve fitter.

    Please refer to Section 6.2 of the Material Reference Doc for details on viscoelastic curve fitting. Also, if you have access to ANSYS customer portal, there is an example worked out in KM 2036139.

  • Hi @jjdoyle thanks for your answer.

    The link you sent appears not to be working properly.

    That is the data I have for the material which I need to simulate.

    How can I insert that into ansys?

    Thanks again

  • jjdoylejjdoyle PittsburghMember

    Translate your graphs into one tabular txt file that looks something like this:

    Where first column of data is frequency, second column is storage modulus and third column is loss modulus.

    Then, you can use the curve fitter in MAPDL Preprocessor to run curve fit to generate prony coefficients in time domain. You will probably have to seed the initial values of tau (relaxation time) to get a successful fit, keeping in mind that the frequency is inversely proportional to time.

    The result would look something like the screenshots below:


  • Once again thanks @jjdoyle for your answer.

    I have done the translation from the graph to a .csv file.

    Where can I find this MAPDL Preprocessor?

    Sorry but I am used to ansys Workbench Interface

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