Approach to failure through record breaking avalanches in a heterogeneous stress field

Abstract

We study how the competition of the disordered local strength and of the evolving inhomogeneous stress field affects the evolution of the series of breaking avalanches accompanying the fracture of heterogeneous materials. To generate fracture processes, we use a fiber bundle model of localized load sharing where the degree of strength disorder is controlled by varying two parameters of the distribution of the breaking threshold of fibers. Analyzing the record statistics of avalanches of breaking fibers, we demonstrate that both for low and high disorders the series of crackling events remains stationary until global failure making the collapse of the system unpredictable. Based on computer simulations, we determine a region of the parameter plane of strength disorder where global failure is preceded by an accelerating breaking activity. We show that the record avalanche with the longest lifetime can be used to identify the onset of acceleration of the fracture process towards the catastrophic failure. Comparison of the results to their equal load sharing counterparts reveals that the accelerating regime is shorter than in case of a homogeneous stress field due to the higher degree of brittleness of the system caused by stress localization.