Characterization of Material Viscoelasticity at Large Deformations

Abstract

Mechanical properties of various technological materials at large deformations are proposed to characterize by means of some generalized parameters obtained at large oscillation strains but not related to any definite rheological equations. The base for the analysis is the Lissajous-Bowditch figures in two coordinate systems - “stress - deformation” and “stress derivative with respect to the phase angle - deformation.” An area of the first of these figures provides the well known integral estimation of dissipative losses in the deformation cycle while the second one presents the new integral measure of the matter’s elasticity. The correlation between the proposed integral estimations of the “averaged” dynamic modulus and the values found in using Fourier and Chebyshev series was demonstrated. This integral method was applied for three suspensions of various types. The obtained results allowed for viewing the type of non-linearity: pseudo-plasticity or dilatancy, stiffening or softening, as functions of deformation.

Keywords

• viscoelaticity
• non-linearity
• large strain
• suspensions