A generalization of the Becker model in linear viscoelasticity: Creep, relaxation and internal friction

TL;DR

This paper introduces a generalized rheological model that interpolates between Maxwell and Becker bodies using a parameter, employing Mittag-Leffler functions to describe creep and relaxation behaviors relevant to geophysics.

Contribution

The paper develops a new linear viscoelastic model parameterized by , generalizing classical models with Mittag-Leffler functions and providing comprehensive analysis of creep, relaxation, and dissipation.

Findings

The model smoothly transitions from Maxwell to Becker behavior as  varies.

Creep and relaxation functions are characterized for different  values.

Frequency-dependent dissipation is computed, relevant for geophysical applications.

Abstract

We present a new rheological model depending on a real parameter $\nu \in [0,1]$ that reduces to the Maxwell body for $\nu=0$ and to the Becker body for $\nu=1$. The corresponding creep law is expressed in an integral form in which the exponential function of the Becker model is replaced and generalized by a Mittag-Leffler function of order $\nu$. Then, the corresponding non-dimensional creep function and its rate are studied as functions of time for different values of $\nu$ in order to visualize the transition from the classical Maxwell body to the Becker body. Based on the hereditary theory of linear viscoelasticity, we also approximate the relaxation function by solving numerically a Volterra integral equation of the second kind. In turn, the relaxation function is shown versus time for different values of $\nu$ to visualize again the transition from the classical Maxwell body to the Becker body. Furthermore, we provide a full characterization of the new model by computing, in addition to the creep and relaxation functions, the so-called specific dissipation $Q^{-1}$ as a function of frequency, which is of particularly relevance for geophysical applications