The collective behavior of dislocations during jerky flow was studied in polycrystalline samples which were subjected to constant strain-rate tests. Dynamic, statistical and multi-fractal analyses were performed on stress-time series, which were recorded during jerky flow, in order to characterize the distinct spatio-temporal dynamic regimes. It was shown that hopping-type B-bands and propagating-type A-bands corresponded to chaotic and self-organized critical states, respectively. The crossover between these types of band was typified by a large spread in the multi-fractal spectrum. The results were interpreted in terms of competing scales and mechanisms.

Multifractal Burst in the Spatiotemporal Dynamics of Jerky Flow. M.S.Bharathi, M.Lebyodkin, G.Ananthakrishna, C.Fressengeas, L.P.Kubin: Physical Review Letters, 2001, 87[16], 165508 (3pp)