Learning Forum

[JHPontes]

Hi all, nI 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.nThanksn

[John Doyle]

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.nPlease 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.n

[JHPontes]

thanks for your answer.nThe link you sent appears not to be working properly.nThat is the data I have for the material which I need to simulate.nHow can I insert that into ansys?nThanks againn

[John Doyle]

Translate your graphs into one tabular txt file that looks something like this:nWhere first column of data is frequency, second column is storage modulus and third column is loss modulus.nThen, 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. nThe result would look something like the screenshots below:n nn

[JHPontes]

Once again thanks for your answer.nI have done the translation from the graph to a .csv file.nWhere can I find this MAPDL Preprocessor? nSorry but I am used to ansys Workbench Interfacen