Regensburg 2013 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 62: Topical Session: Fundamentals of Fracture - Stochastic Aspects
MM 62.2: Vortrag
Donnerstag, 14. März 2013, 17:45–18:00, H4
Time evolution of creep rupture due to thermally activated cracking in a fiber bundle model — •Ferenc Kun1, Naoki Yoshioka2, and Nobuyasu Ito3 — 1Department of Theoretical Physics, University of Debrecen, P.O.Box: 5, H-4010 Debrecen, Hungary — 2Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-cho, 606-8502 Kyoto, Japan — 3Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
We study sub-critical fracture driven by thermally activated crack nucleation under a constant external load in the framework of fiber bundle models. We show that in the presence of stress inhomogeneities, 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, where the exponent depends on the external load and on the temperature.
On the microlevel, thermal fluctuations trigger bursts of breakings which proved to have a power law size distribution. Focusing on the waiting times between consecutive bursts we show that the time evolution has two distinct forms: at high load values the breaking process continuously accelerates towards macroscopic failure, however, for low loads and high enough temperatures the acceleration is preceded by a slow-down. Analyzing the structural entropy and the location of consecutive bursts we show that in the presence of stress concentration the early acceleration is the consequence of damage localization.