| الملخص: | We investigate the statistics of record breaking events in the time series of <br/>crackling<br/>bursts in a fiber bundle model of the creep rupture of heterogeneous materials. <br/>In the model fibers break due to two mechanisms: <br/>slowly accumulating damage triggers bursts of immediate breakings analogous<br/>to acoustic emissions in experiments. The rupture process accelerates such that <br/>the size of breaking <br/>avalanches increases while the waiting time between consecutive events decreases <br/>towards failure.<br/>Record events are defined as bursts which have a larger size than all previous <br/>events in the <br/>time series.<br/>We analyze the statistics of records focusing on the limit of equal load sharing <br/>(ELS) <br/>of the model and compare <br/>the results to the record statistics of sequences of independent identically <br/>distributed <br/>random variables. Computer simulations revealed that the number of records grows <br/>with the logarithm <br/>of the event number except for the close vicinity of macroscopic failure where <br/>an exponential dependence is<br/>evidenced. The two regimes can be attributed to the dominance of disorder with <br/>small burst sizes<br/>and to stress enhancements giving rise efficient triggering of extended bursts, <br/>respectively.<br/>Both the size of records and the increments between consecutive record events<br/>are characterized by power law distributions with a common exponent 1.33 <br/>significantly different<br/>from the usual ELS burst size exponents of fiber bundles. The distribution of <br/>waiting times follows<br/>the same behavior, however, with two distinct exponents for low and high loads. <br/>Studying the <br/>evolution of records we identify a load dependent characteristic scale of the <br/>system<br/>which separates slow down and acceleration of record breaking as failure is <br/>approached.
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