History effects in the creep of a disordered brittle material

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2023-03

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en

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12
1-12

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Physical Review Materials, Volume 7, issue 3

Abstract

We study the creep behavior of a disordered brittle material (concrete) under successive loading steps, using acoustic emission and ultrasonic sensing to track internal damage. The primary creep rate is observed to follow a (Omori-type) power-law decay in the strain rate, the number of acoustic emission events, as well as the amplitudes of the ultrasonic beams, supporting a brittle-creep mechanism. The distribution of acoustic emission event energies is observed to have a scale-free power-law distribution instead of a truncated one expected for a system approaching a critical point at failure. The main outcome is, however, the discovery of unexpected history effects that make the material less prone to creep when it has been previously deformed and damaged under primary creep. With the help of a progressive damage model implementing thermal activation, we interpret this as an aging-under-stress phenomenon: During an initial creep step at relatively low applied stress, the easy-to-damage sites are exhausted first, depleting the excitation spectrum at low stress gap values. Consequently on reloading, although previously damaged, the primary creep restarts but the material creeps (and damages) less than it would under the same stress but without precreeping. Besides shedding a new light on the fundamental physics of creep of disordered brittle materials, this has important practical consequences in the interpretation of some experimental procedures, such as stress-stepping experiments.

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Funding Information: We thank Chi-Cong Vu for the sample preparation, Philémon Peltier for the implementation of the KMC algorithm, and Mikko Alava and Carmen Miguel for useful discussions. ISTerre is part of Labex OSUG@2020. T.M. acknowledges funding from the European Union Horizon 2020 research and innovation program under Grant No. 857470 and from European Regional Development Fund via Foundation for Polish Science International Research Agenda PLUS program Grant No. MAB PLUS/2018/8. The Aalto Science IT project is acknowledged for computational resources. | openaire: EC/H2020/857470/EU//NOMATEN

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Citation

Mäkinen , T , Weiss , J , Amitrano , D & Roux , P 2023 , ' History effects in the creep of a disordered brittle material ' , Physical Review Materials , vol. 7 , no. 3 , 033602 , pp. 1-12 . https://doi.org/10.1103/PhysRevMaterials.7.033602