Question

How to find the prony series parameters from frequency domain data?

Answer 1

You can do this using Excel by defining the Prony series equation based on some initial constant trial values and using it to predict the modulus based on frequency or time (which ever you used in your DMA test). Sum the squared error between the experimental and trial Prony series calculations and minimize using the "Solver" function in Excel by allowing Solver to vary the parameters to achieve the closest agreement with experimental results.

I must caution you that fitting Prony series is very much dependent on your initial trial values and you could achieve multiple "fit"s for the same data. Thus some understanding of the meaning and physical interpretation of the parameters is needed in order input realistic initial values.