Thermally induced creep rupture of fiber bundles

摘要

Subcritical fracture driven by thermally activated crack nucleation is studied in the framework of a fiber bundle model.Based on analytic calculations and computer simulations,we show that,in the presence of stress inhomogeneity thermally activated cracking results in an anomalous size effect,i.e.,the average lifetime of the system decreases as a power-law of the system size.We propose a modified Arrhenius law which provides a comprehensive description of the load,temperature,and size dependence of the lifetime of the system.On the microscopic level,thermal fluctuations trigger bursts of breaking events which proved to have a power-law size distribution.The waiting times between consecutive bursts are also power-law distributed with an exponent switching between 1 and 2 as the load and temperature are varied.Analyzing the structural entropy and the location of consecutive bursts,we show that,in the presence of stress concentration,the acceleration of the rupture process close to failure is the consequence of damage localization.