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Quasi-periodic events in crystal plasticity and the self-organized avalanche oscillator

机译：晶体可塑性中的准周期性事件和自组织雪崩振荡器

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摘要

很多系统都对慢慢增加的外部压力做出冲动性反应。正常情况下，平稳的压力释放过程会被大型随机事件(或雪崩式事件)间歇性地中断，使系统发生突然的结构变化。在一个由被压缩的镍微晶组成的勺模型系统中通过将理论和实验相结合，Stefarnos Papanikolaou圾其同事研究了一个中间体系，在其中平稳的背景过程以与外部驱动压力相似的速度发生，导致在快速雪崩事件本身中异乎寻常地观察到振荡行为。原则上，这一发现适用于具有共存的慢速松弛来与其竞争、以减小局部内压力的所有间歇性现rn象。这一描述将包括处在松弛过程中的复杂网络(如大脑)、紊乱的／壅塞的固体和地震断层，迫使我们对实验和模拟数据进行重新解读。本期封面所示为一个镍微晶阵列，其上覆盖着圣安德烈亚斯断层的轮廓线；在该断层上，在微晶中所观察到的力在更大尺度上发挥作用。(微晶阵列由Derlnis M．Dirtliduk提供；rn断层由D K Lynch／USGS提供)。%When external stresses in a system-physical, social or virtual-are relieved through impulsive events, it is natural to focus on the attributes of these avalanches~(1,2). However, during the quiescent periods between them~3, stresses may be relieved through competing processes, such as slowly flowing water between earthquakes~4 or thermally activated dislocation flow~5 between plastic bursts in crystals~(6-8). Such smooth responses can in turn have marked effects on the avalanche properties~9. Here we report an experimental investigation of slowly compressed nickel microcrystals, covering three orders of magnitude in nominal strain rate, in which we observe unconventional quasi-periodic avalanche bursts and higher critical exponents as the strain rate is decreased. Our experiments are faithfully reproduced by analytic and computational dislocation avalanche modelling~(10,11) that we have extended to incorporate dislocation relaxation, revealing the emergence of the self-organized avalanche oscillator: a novel critical state exhibiting oscillatory approaches towards a depinning critical point~12. This theory suggests that whenever avalanches compete with slow relaxation-in settings ranging from crystal microplasticity to earthquakes- dynamical quasi-periodic scale invariance ought to emerge.
机译：很多系统都对慢慢增加的外部压力做出冲动性反应。正常情况下，平稳的压力释放过程会被大型随机事件(或雪崩式事件)间歇性地中断，使系统发生突然的结构变化。在一个由被压缩的镍微晶组成的勺模型系统中通过将理论和实验相结合，Stefarnos Papanikolaou圾其同事研究了一个中间体系，在其中平稳的背景过程以与外部驱动压力相似的速度发生，导致在快速雪崩事件本身中异乎寻常地观察到振荡行为。原则上，这一发现适用于具有共存的慢速松弛来与其竞争、以减小局部内压力的所有间歇性现rn象。这一描述将包括处在松弛过程中的复杂网络(如大脑)、紊乱的／壅塞的固体和地震断层，迫使我们对实验和模拟数据进行重新解读。本期封面所示为一个镍微晶阵列，其上覆盖着圣安德烈亚斯断层的轮廓线；在该断层上，在微晶中所观察到的力在更大尺度上发挥作用。(微晶阵列由Derlnis M．Dirtliduk提供；rn断层由D K Lynch／USGS提供)。%When external stresses in a system-physical, social or virtual-are relieved through impulsive events, it is natural to focus on the attributes of these avalanches~(1,2). However, during the quiescent periods between them~3, stresses may be relieved through competing processes, such as slowly flowing water between earthquakes~4 or thermally activated dislocation flow~5 between plastic bursts in crystals~(6-8). Such smooth responses can in turn have marked effects on the avalanche properties~9. Here we report an experimental investigation of slowly compressed nickel microcrystals, covering three orders of magnitude in nominal strain rate, in which we observe unconventional quasi-periodic avalanche bursts and higher critical exponents as the strain rate is decreased. Our experiments are faithfully reproduced by analytic and computational dislocation avalanche modelling~(10,11) that we have extended to incorporate dislocation relaxation, revealing the emergence of the self-organized avalanche oscillator: a novel critical state exhibiting oscillatory approaches towards a depinning critical point~12. This theory suggests that whenever avalanches compete with slow relaxation-in settings ranging from crystal microplasticity to earthquakes- dynamical quasi-periodic scale invariance ought to emerge.

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  • 来源
    《Nature》 |2012年第7421期|p.517-521A3|共6页
  • 作者

    Stefanos Papanikolaou; Dennis M. Dimiduk; Woosong Choi; James P. Sethna; Michael D. Uchic; Christopher F. Woodward; Stefano Zapperi;

  • 作者单位

    Department of Mechanical Engineering and Materials Science and Department of Physics, Yale University, New Haven, Connecticut 06520-8286, USA;

    Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Ohio 45433, USA;

    Iaboratory of Atomic and Solid State Physics, Department of Physics, Clark Hall, Cornell University, Ithaca, New York 14853-2501, USA;

    Iaboratory of Atomic and Solid State Physics, Department of Physics, Clark Hall, Cornell University, Ithaca, New York 14853-2501, USA;

    Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Ohio 45433, USA;

    Air Force Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Ohio 45433, USA;

    CNR-Consiglio Nazionale delle Ricerche, IENI, Via R. Cozzi 53,20125 Milano, Italy ISI Foundation, Via Alassio 11/c, 10126 Torino, Italy;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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