| Sumario: | Quasi‐static and dynamical tests are employed to measure the modulus or the compliance of a material as a function of time or frequency, and to determine the respective distribution function in the case of a linear viscoelastic medium. The evolution of the mechanical properties, and consequently the distribution functions, are usually described by empirical expressions which cannot always be interpreted according to a physical model. Furthermore, as a rule these empirical distributions do not lead to closed expressions for all the viscoelastic functions. The mechanical properties of viscoelastic materials (amorphous polymers, metallic glasses, etc.) are described using a modified anelastic element (MAE). This modified element is analogous to the standard anelastic element, having a single characteristic time, τ, that is not a constant but a function of time or frequency. On considering a particular functional dependence of τ, it is demonstrated how several empirical viscoelastic functions are approximations of the mechanical properties of the MAE. Moreover, this functional dependence is related to the log‐normal distribution the statistical and physical meanings of which are discussed in detail. Copyright © 1993 WILEY‐VCH Verlag GmbH & Co. KGaA
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