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    朱一超

    • 教授     博士生导师   硕士生导师
    • 性别:男
    • 毕业院校:牛津大学
    • 学位:博士
    • 所在单位:力学与航空航天学院
    • 学科:固体力学. 应用数学
    • 办公地点:工程力学系407室
    • 电子邮箱:yichaozhu@dlut.edu.cn

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    Characterisation of dislocation patterning behaviour with a continuum dislocation dynamics model on two parallel slip planes equipped with a deep neural network resolving local microstructures

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    论文类型:期刊论文

    发表时间:2020-08-01

    发表刊物:INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

    收录刊物:SCIE

    卷号:198

    页面范围:57-71

    ISSN号:0020-7683

    关键字:Dislocation; Pattern formation; Discrete-to-continuum transition; Machine learning; Asymptotic analysis

    摘要:The self-organisation behaviour of dislocation upon loading is still a mechanistically mysterious phenomenon. The present article aims to present a computationally tractable dislocation dynamics model, which can be used for helping analyse the mechanism behind dislocation pattern formation. With an integrated use of asymptotic analysis and machine learning tools, the discrete dislocation dynamics on two parallel slip planes is self-consistently reformulated at a coarse-grained level. For the present case, asymptotic analysis helps in 1) reformulating the original globally discrete problem by a continuum model underpinned by a database resolving the almost singular short-range elastic interaction of discrete dislocations; 2) identifying the proper input and output quantities for implementing machine learning tools; 3) digging out a hidden but explicit interrelation between mean-field quantities to reduce the dimensionality of the data space. Machine learning tools serve for 1) inferring the inherently implicit interrelationships between continuum quantities; 2) capturing a low-dimensional manifold in the data space corresponding to the local flow stress. The non-monotonically increasing profile of the flow stress - density relationship, as revealed by machine learning, is found to play a key role in the onset of dislocation patterning behaviour seen in the simulation results. A scaling law relating the applied stress to pattern wavelength is also derived, providing a rationale to the widely used empirical similitude relation. The experimentally observed swing in similitude coefficient value is attributed to the randomness in slip plane distributions. In a methodological viewpoint, the treatment of using asymptotic analysis to help design the curriculum for implementing machine learning tools, offers a paradigm for self-consistently upscaling more complicated multiscale systems. (C) 2020 Elsevier Ltd. All rights reserved.