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Shear avalanches in plastic deformation of a metallic glass composite

INTERNATIONAL JOURNAL OF PLASTICITY 2016年 77卷 141-155页

作者： Tong, X. Wang, G. Yi, J. Ren, J. L. Pauly, S. Gao, Y. L. Zhai, Q. J. Mattern, N. Dahmen, K. A. Liaw, P. K. Eckert, J. Shanghai Univ Lab Microstruct Shanghai 200444 Peoples R China Zhengzhou Univ Sch Math & Stat Zhengzhou 450001 Peoples R China IFW Dresden Inst Complex Mat POB 270116 D-01069 Dresden Germany Univ Illinois Dept Phys 1110 W Green St Urbana IL 61801 USA Univ Tennessee Dept Mat Sci & Engn Knoxville TN 37996 USA Austrian Acad Sci Erich Schmid Inst Mat Sci Jahnstr 12 A-8700 Leoben Austria Univ Leoben Dept Mat Phys Jahnstr 12 A-8700 Leoben Austria

Changes in intermittent shear avalanches during plastic deformation of a Cu50Zr45Ti5 (atomic percent) alloy in response to variant structures including fully glassy phase and/or nanocrystal/glass binary phase are investigated. Second crystalline phases are introduced into the glassy-phase matrix of a Cu50Zr45Ti5 metallic glass to interfere with the shear avalanche process, which can release the shear strain concentration, and then tune the critically-dynamic behavior of the shear avalanche. By combining microstructural observations of the nanocrystals with the statistical analysis of the corresponding deformation behavior, we determine the statistic distribution of shear-avalanche sizes during plastic deformation, and established its dependence on the geometric distribution of nano crystals. The scaling behavior of the distribution of shear-avalanche sizes follows a power law relation accompanied by an exponentially-decaying scaling function in the pure metallic glass, and the metallic glass containing the small nanocrystals, which can be described by the mean-field theory. The large shear-avalanche events are dominated by structural tuning-parameters, i.e., the resistance of shear banding, and the size and volume fraction of the second crystalline phase in metallic glasses. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Twinning Glass material probability and statistics Dynamics of shear avalanche

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The influence of dispersity in geometric structure on the stability of cellular solids

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MECHANICS OF MATERIALS 2007年第2期39卷 183-198页

作者： Schraad, M. W. Los Alamos Natl Lab Fluid Dynam Grp Div Theoret Los Alamos NM 87545 USA

Geometric structures in cellular solids span the spectrum from perfectly periodic to strictly random. Depending on the degree of disorder at the cellular-scale, the corresponding continuum-scale mechanical response can admit instabilities or can remain stable for the entire range of compressive deformations. In the present work, the response of cellular materials to quasi-static uni-axial compression is investigated. The underlying geometric structures in these materials are allowed to range from highly ordered to highly disordered, and the corresponding transition from unstable to stable mechanical response is explored. A stochastic constitutive model is developed and used for this purpose. Model development begins with an established cellular-scale mechanical response description, but this cellular-scale model is generalized to accommodate finite strain. A continuum-scale constitutive model is established by averaging the cellular-scale model over an ensemble of foam cells, and stochastic variation in cellular-scale geometric structure and material properties is considered through the use of probability density functions for the associated model parameters. Results show that dispersity in geometric structure has little to no effect on the initial elastic properties of the cellular materials under investigation. For deformations occurring prior to any occurrence of instability, however, increasing dispersity is accompanied by decreasing stiffness, an increase in critical strain, and a decrease in the extent of localized deformation. Most notably, materials with the highest degrees of dispersity in their cellular structures exhibit mechanical response that remains stable for the entire range of compressive deformations, demonstrating a general stabilizing effect of dispersity in geometric structure on the continuum-scale mechanical response of cellular solids. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： microstructures finite strain foam material probability and statistics stability and bifurcation

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Reconstruction of transcriptional network from microarray data using combined mutual information and network-assisted regression

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IET SYSTEMS BIOLOGY 2011年第2期5卷 95-U42页

作者： Wang, X. -D. Qi, Y. -X. Jiang, Z. -L. Shanghai Jiao Tong Univ Sch Life Sci & Biotechnol Inst Mechanobiol & Med Engn Shanghai 200240 Peoples R China

Many methods had been developed on inferring transcriptional network from gene expression. However, it is still necessary to design new method that discloses more detailed and exact network information. Using network-assisted regression, the authors combined the averaged three-way mutual information (AMI3) and non-linear ordinary differential equation (ODE) model to infer the transcriptional network, and to obtain both the topological structure and the regulatory dynamics. Synthetic and experimental data were used to evaluate the performance of the above approach. In comparison with the previous methods based on mutual information, AMI3 obtained higher precision with the same sensitivity. To describe the regulatory dynamics between transcription factors and target genes, network-assisted regression and regression without network, respectively, were applied in the steady-state and time series microarray data. The results revealed that comparing with regression without network, network-assisted regression increased the precision, but decreased the fitting goodness. Then, the authors reconstructed the transcriptional network of Escherichia coli and simulated the regulatory dynamics of genes. Furthermore, the authors' approach identified potential transcription factors regulating yeast cell cycle. In conclusion, network-assisted regression, combined AMI3 and ODE model, was a more precisely to infer the topological structure and the regulatory dynamics of transcriptional network from microarray data.

关键词： microorganisms probability theory, stochastic processes, and statistics Biology and medical computing probability and statistics network-assisted regression Escherichia coli data analysis Nonlinear and functional equations (numerical analysis) regression analysis Genomic techniques averaged three-way mutual information time series microarray data Physics of subcellular structures nonlinear ordinary differential equation model genomics nonlinear differential equations cellular biophysics Data handling techniques bioinformatics AM13 model gene expression cell cycle Function theory, analysis time series transcriptional network lab-on-a-chip genetics

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The effect of multiple sources of uncertainty on the convex hull of material properties of polycrystals

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COMPUTATIONAL MATERIALS SCIENCE 2009年第2期47卷 342-352页

作者： Kouchmeshky, Babak Zabaras, Nicholas Cornell Univ Mat Proc Design & Control Lab Sibley Sch Mech & Aerosp Engn Ithaca NY 14853 USA

Quantification and propagation of uncertainty in process conditions and initial microstructure on the final product properties in a deformation process are presented. The stochastic deformation problem is modeled using a sparse grid collocation approach that allows the utilization of a deterministic simulator to build interpolants of the main solution variables in the stochastic support space. The ability of the method in estimating the statistics of the macro-scale microstructure-sensitive properties and constructing the convex hull of these properties is shown through examples featuring randomness in initial texture and process parameters. A data-driven model reduction methodology together with a maximum entropy approach are used for representing randomness in initial texture in Rodrigues space. Comparisons are made with the results obtained from the Monte-Carlo method. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Polycrystal plasticity Processing Texture Mechanical properties probability and statistics Uncertainty quantification

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Non-local effective relations for fibre-reinforced composites loaded by configuration-dependent body forces

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2001年第11期49卷 2705-2717页

作者： Luciano, R Willis, JR Univ Bath Dept Math Sci Bath BA2 7AY Avon England Univ Cassino DIMSAT I-03043 Cassino Fr Italy

In this paper, fibre-reinforced media are analysed. The distribution of the fibres is assumed random. A combination of deterministic and configuration-dependent body forces is considered. In this case, several non-local effective constitutive operators must be taken into account in order to define the mean response of the material. For two phase composites, expressions for all these operators have been obtained and in the case of fibre-reinforced materials Hashin-Shtrikman type bounds are explicitly developed in the real and the Fourier space, Finally, a periodic distribution of fibres is studied as an example. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： microstructures constitutive behaviour inhomogeneous material energy methods integral transforms probability and statistics

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An analytical model for the translaminar fracture toughness of fibre composites with stochastic quasi-fractal fracture surfaces

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2014年第1期66卷 78-102页

作者： Pimenta, Soraia Pinho, Silvestre T. Univ London Imperial Coll Sci Technol & Med Dept Aeronaut London SW7 2AZ England

The translaminar fracture toughness of fibre-reinforced composites is a size-dependent property which governs the damage tolerance and failure of these materials. This paper presents the development, implementation and validation of an original analytical model to predict the tensile translaminar (fibre-dominated) toughness of composite plies and bundles, as well as the associated size effect. The model considers, as energy dissipation mechanisms, debonding and pull-out of bundles from quasi-fractal fracture surfaces;the corresponding lengths are stochastic variables predicted by the model, based on the respective bundle strength distributions and fracture mechanics. Parametric studies show that composites are toughened by stronger fibres with large strength variability, and intermediate values of interfacial toughness and friction. Predictions are validated against four different composite ply systems tested in the literature, proving the models ability to capture not only size effects, but also the influence of different fibres and resins. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Strengthening and mechanisms Fibre-reinforced composite material probability and statistics Size effects Translaminar fracture toughness

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Bayesian characterization of correlation between uniaxial compressive strength and Young's modulus of rock

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INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 2016年 85卷 10-19页

作者： Wang, Yu Aladejare, Adeyemi Emman City Univ Hong Kong Dept Architecture & Civil Engn Tat Chee Ave Kowloon Hong Kong Peoples R China

The uniaxial compressive strength (UCS) and Young's modulus (E) of rock are important mechanical parameters in rock engineering design and construction. UCS and E are also correlated and the correlation has important effect on reliability analysis in rock engineering. However, the UCS and E data obtained for a project site is generally limited, and the sparse number of UCS and E data often obtained is not sufficient to provide joint probability distribution of UCS and E and to estimate their correlation coefficient. This poses a challenge in many rock engineering reliability analyses. This paper aims to address this challenge by developing Bayesian approach for obtaining site-specific joint probability distribution of the uniaxial compressive strength (UCS) and the Young's modulus (E), and for quantifying the site-specific correlation between UCS and E for a project site. The Bayesian approach characterizes the joint probability distribution of UCS and E, using the available limited amount of site-specific UCS and E data and a regression model. The proposed approach integrates the limited site-specific UCS and E data with regression model and prior knowledge, and it transforms the integrated knowledge into a large number of UCS and E sample pairs using Markov Chain Monte Carlo (MCMC) simulation. Then, the correlation coefficient of the UCS and E sample pairs is obtained, together with marginal distributions of UCS and E, and their mean and standard deviation. The proposed approach effectively tackles the difficulty of estimating site -specific correlation coefficient and joint probability distribution from usually sparse test data of UCS and E obtained during investigation of a project site. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Bayesian approach Correlation coefficient probability and statistics Markov Chain Monte Carlo simulation Variability and uncertainty

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Probabilistic analysis of micro-film buckling with parametric uncertainty

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STRUCTURAL ENGINEERING AND MECHANICS 2014年第5期50卷 697-708页

作者： Ying, Zuguang Wang, Yong Zhu, Zefei Zhejiang Univ Dept Engn Mech Sch Aeronaut & Astronaut Hangzhou 310027 Zhejiang Peoples R China Hangzhou Dianzi Univ Sch Mech Engn Hangzhou 310018 Zhejiang Peoples R China

The intentional buckling design of micro-films has various potential applications in engineering. The buckling amplitude and critical strain of micro-films are the crucial parameters for the buckling design. In the reported studies, the film parameters were regarded as deterministic. However, the geometrical and physical parameters uncertainty of micro-films due to manufacturing becomes prominent and needs to be considered. In the present paper, the probabilistic nonlinear buckling analysis of micro-films with uncertain parameters is proposed for design accuracy and reliability. The nonlinear differential equation and its asymptotic solution for the buckling micro-film with nominal parameters are firstly established. The mean values, standard deviations and variation coefficients of the buckling amplitude and critical strain are calculated by using the probability densities of uncertain parameters such as the film span length, thickness, elastic modulus and compressive force, to reveal the effects of the film parameter uncertainty on the buckling deformation. The results obtained illustrate the probabilistic relation between buckling deformation and uncertain parameters, and are useful for accurate and reliable buckling design in terms of probability.

关键词： probability and statistics buckling thin film uncertainty parameters nonlinearity

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Material-independent crack arrest statistics

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2004年第7期52卷 1651-1669页

作者： Charles, Y Vandembroucq, D Hild, F Roux, S Univ Paris 06 CNRS ENS LMT ChachanUMR 8535 F-93303 Cachan France CNRS Lab Surface Verre & Interfaces UMR F-93303 Aubervilliers France

The propagation of (planar) cracks in a heterogeneous brittle material characterized by a random field of toughness is considered, taking into account explicitly the effect of the crack front roughness on the local stress intensity factor. In the so-called strong-pinning regime, the onset of crack propagation appears to map onto a second-order phase transition characterized by universal critical exponents which are independent of the local characteristics of the medium. Propagation over large distances can be described by using a simple one-dimensional description, with a correlation length and an effective macroscopic toughness distribution that scale in a non-trivial fashion with the crack front length. As an application of the above concepts, the arrest of indentation cracks is addressed, and the analytical expression for the statistical distribution of the crack radius at arrest is derived. The analysis of indentation crack radii on alumina is shown to obey the predicted algebraic expression for the radius distribution and its dependence on the indentation load. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： crack propagation and arrest indentation and hardness inhomogeneous material probability and statistics brittle material

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Probabilistic analysis of micro-machined fixed-fixed beam for reliability

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MICRO & NANO LETTERS 2008年第3期3卷 95-100页

作者： Islam, Md. Fokhrul Ali, M. A. Mohd. Majlis, B. Y. Univ Kebangsaan Malaysia Fac Engn & Built Environm Dept Elect Elect & Syst Engn Bangi 43600 Selangor Malaysia Univ Kebangsaan Malaysia IMEN Bangi 43600 Selangor Malaysia Univ Kebangsaan Malaysia Inst Space Sci ANGKASA Bangi 43600 Selangor Malaysia

A realistic approach for modelling a fixed-fixed beam is presented. The use of probabilistic methods to assess the electromechanical behaviour of the beam under the presence of micro-machine manufacturing and process uncertainties is demonstrated. A finite-element model of the beam is constructed using the commercial code ANSYS (10.0). In the standard approach of modelling, existing literature assumes deterministic values for design parameters, however, fabrication of the device introduces some amount of variation in the design parameters. Here, the probabilistic approach is discussed to account for the variability in fabrication. Probabilistic analysis guides the design of the fixed-fixed beam to achieve a robust and reliable design in the most efficient way. The results of the probabilistic design approach on the performance characteristics such as maximum deflection and maximum stress will be discussed.

关键词： reliability probabilistic analysis Reliability Design and modelling of MEMS and NEMS devices probability theory, stochastic processes, and statistics Micromechanical and nanomechanical devices and systems Finite element analysis probability and statistics Numerical approximation and analysis micromachined fixed-fixed beam probability finite-element model micromechanical devices design parameters beams (structures) micromachining ANSYS code microelectromechanical systems finite element analysis

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