On Slow Dynamic Elasticity at short times

TL;DR

This paper investigates slow dynamic elastic relaxations at short times across various materials, finding no evidence of the previously reported transition to diminished relaxation rates, despite experimental limitations.

Contribution

It provides new observations of elastic relaxation behaviors at short times in different materials, challenging prior reports of a transition in relaxation rates.

Findings

No reliable sign of the transition at short times in the studied systems.

Relaxation behavior appears consistent without the predicted late cutoff.

Experimental limitations affect the precise determination of relaxation onset.

Abstract

It has been reported that slow dynamic nonlinear elastic relaxations, widely thought to proceed in proportion to the logarithm of time since mechanical conditioning ceases, recover at a diminished rate at early times, with a time of transition that varies with the grain size of the material. Here we recount new observations at short times, in the single bead system, in cement paste and in sandstone and mortar. Notwithstanding the limits imposed by finite duration ring down such that the effective instant of conditioning cessation is imprecise, and the corresponding ambiguity as to the time that relaxation begins, we find no reliable sign of such a transition, even in samples of large grain size mortar similar to those described elsewhere as having clear and late cutoffs.