TRANSIENT RESPONSES OF POLYMERS AND ELASTOMERS DEDUCED FROM HARMONIC RESPONSES

The problem of interrelations between viscoelastic time and frequency functions is revisited. The proposed methods do not use the intermedia ry functions which are extensively used in the rheology of solid mater ials. Integer linear differential operators or fractional derivatives for constitutive equations relating stress and strain are the two poss ibilities of choice. From experimental curves of complex moduli versus frequency, obtained over a large range of frequencies, closed form ex pressions of moduli are obtained. Inverse Fourier transformation gives rise to time exponential series or time hypergeometric series dependi ng on the type of constitutive law adopted. (C) 1997 Academic Press Li mited.