Berlin 2005 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 44: Growth and Fracture
DY 44.6: Vortrag
Dienstag, 8. März 2005, 17:00–17:15, TU H3010
Slow crack propagation in heterogeneous materials — •Jan Kierfeld1 and Valerii Vinokur2 — 1MPI für Kolloid- und Grenzflächenforschung, Potsdam — 2Materials Science Division, Argonne National Laboratory
We consider crack nucleation and propagation in a heterogeneous two-dimensional material. Using the generalized Griffith criterion for crack propagation we derive an equation of motion for the crack tip position, which includes dissipation, thermal noise and quenched random forces due to heterogeneities. Depending on the exponent characterizing the power-law decay of the random forces we find qualitatively different behavior of propagating cracks. Sufficiently long-range random forces, as they are realized for frozen dislocations, lead to complete crack arrest thus preventing fracture. Random impurities lead to slowly propagating cracks with creep dynamics. Our results explain the enhanced fracture stability of certain heterogeneous materials, in particular, of work-hardened materials with frozen dislocations.