Load-Dependent Power-Law Exponent in Creep Rupture of Heterogeneous Materials

TL;DR

This study reveals that the power-law exponent in creep rupture of heterogeneous materials varies with load and direction, challenging the notion of its independence from applied stress, supported by experiments and fiber bundle simulations.

Contribution

It demonstrates experimentally and through simulations that the creep rupture exponent depends on load and direction, highlighting the importance of load conditions in material failure.

Findings

Exponent varies with applied load and direction

Fiber bundle model reproduces load dependence

Creep dynamics are influenced by load conditions

Abstract

Creep tests on heterogeneous materials under subcritical loading typically show a power-law decaying strain rate before failure, with the exponent often considered material-dependent but independent of applied stress. By imposing successive small stress relaxations through a displacement feedback loop, we probe creep dynamics and show experimentally that this exponent varies with both applied load and loading direction. Simulations of a disordered fiber bundle model reproduce this load dependence, demonstrating that such models capture essential features of delayed rupture dynamics.