The discrete relaxation time spectrum can be extracted by fitting following model with n user selectable terms to either oscillation (G’(w), G”(w)) or Relaxation (G(t)) data.
The spectrum represents n pairs of fitted {Gi,ti} parameters and can be extracted into a new file if desired. The number of terms is user selectable. For most applications, 6 terms are sufficient to describe the material’s viscoelastic response.
Use this model to extract the Relaxation time spectrum. The Relaxation time spectrum is used to interconvert linear viscoelastic material functions such as G’, G” to G(t); G’, G” to h(t) and y1(t); etc.
The calculation of the Relaxation Time Spectrum from experimental data is an ill-posed problem, in that small differences in the data can result in large differences in the spectra. Selecting too many modes does not improve the accuracy of the solution, but creates physically meaningless modes. The automatic mode selection optimizes the solution and determines the optimum number of modes.
