title: Fractal frontiers of bursts and cracks in a fiber bundle model of creep rupture.
abstract: We investigate the geometrical structure of breaking bursts generated during the creep rupture of heterogeneous materials. Using a fiber bundle model with localized load sharing we show that bursts are compact geometrical objects; however, their external frontiers have a fractal structure which reflects their growth dynamics. The perimeter fractal dimension of bursts proved to have the universal value 1.25 independent of the external load and of the amount of disorder in the system. We conjecture that according to their geometrical features, breaking bursts fall in the universality class of loop-erased self-avoiding random walks with perimeter fractal dimension 5/4 similar to the avalanches of Abelian sand pile models. The fractal dimension of the growing crack front along which bursts occur proved to increase from 1 to 1.25 as bursts gradually cover the entire front.
authors.affiliation: Department of Theoretical Physics, University of Debrecen, P.O. Box 5, H-4010 Debrecen, Hungary.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Danku
authors.affiliation: Department of Theoretical Physics, University of Debrecen, P.O. Box 5, H-4010 Debrecen, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Kun
authors.affiliation: Computational Physics IfB, HIF, ETH, Hönggerberg, 8093 Zürich, Switzerland and Departamento de Fisica, Universidade Federal do Ceara, 60451-970 Fortaleza, Ceara, Brazil.
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Herrmann