Comparison of viscoelastic moduli fitting using optimization methods

Abstract

Usually, viscoelastic models based on Prony’s series are used to fit the master curves from experimental results. However, the fitting process requires previous knowledge of the time-parameters of the model, τ_i, in order to fit the corresponding modulus. In general, a homogeneous distribution in logarithmic-time scale is used for τ_i, but a large number of terms in the Prony’s series are needed to achieve a suitable fitting that cannot be implemented into a commercial finite element code, in which the number of terms can be limited. As an alternative, a new optimizing methodology for fitting master curves of viscoelastic materials with Prony-based models is presented. This approach can be applied to the definition of different experimental viscoelastic master curves, such as those related to relaxation or creep. Finally, the results are compared with those obtained with the homogeneous distribution fitting method