A micromechanical model of the evolution of stress and strain fields in ultrafine-grained metal structures under tension

“…Some groups of researchers used the quasireal (e.g., Voronoi tessellation based) representations of structures, with some real structure parameters, to represent realistic microstructures of nanometals [28][29][30][31] (see an example Figure 1c). So, Mercier et al [32] considered nanocrystalline material as an aggregate of spherical grains, with random grain sizes, distributed according to lognormal probability distribution.…”

Section: Multi-element Composite Models and Homogenizationmentioning

confidence: 99%

“…Using the Voronoi type composite model, Collini and Bonardi [30] demonstrated that the strength of nanometals depend on the strain variability, which in turn is controlled by the variation of grain sizes. According to [30], contributions of grains of different sizes to deformation are different.…”

Section: Multi-element Composite Models and Homogenizationmentioning

confidence: 99%

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Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Mishnaevsky

Левашов

2015

Computational Materials Science

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Abstract:An overview of micromechanical models of strength and deformation behaviour of nanostructured and ultrafine grained metallic materials is presented. Composite models of nanomaterials, polycrystal plasticity based models, grain boundary sliding, the effect of nonequilibrium grain boundaries and nanoscale properties are discussed and compared. The examples of incorporation of peculiar nanocrystalline effects (like large content of amorphous or semi-amorphous grain boundary phase, partial dislocation GB emission/glide/GB absorption based deformation mechanism, diffusion deformation, etc.) into continuum mechanical approach are given. The possibilities of using micromechanical models to explore the ways of the improving the properties of nanocrystalline materials by modifying their structures (e.g., dispersion strengthening, creating non-equilibrium grain boundaries, varying the grain size distributions and gradients) are discussed.Keywords: Micromechanics; Finite element modelling; Nanomaterials; Nanocrystalline materials IntroductionDuring recent decades, growing interest of scientific community has been attracted to the nanostructured materials. The expectations on nanostructuring as a way to enhance material performances and to improve competing materials properties are very high, and some of them have been delivered, indeed.The extraordinary properties of nanocrystalline and ultrafine grained metallic materials (i.e., materials with the grain sizes of the order of several to several hundred nanometers) include superductility at room temperature, high hardness and high strength 2 to hardness value (which might be 2…7 times higher than in coarse grained materials), lower elastic modulus, negative Hall-Petch slope, enhanced strain rate sensitivity and difference between tensile and compression response [1][2][3][4][5]. The yield strength of nanocrystalline materials can be up to 5…10 times higher than of coarse-grained materials [6]. Other peculiar effect of nanocrystalline materials are the deviation fromHall-Petch relation at ultrafine and nanoscale grain sizes (below 100 nm), which goes into negative Hall Petch slope at about 10 nm, as well as asymmetry of tensile and compressive behaviour and enhanced diffusion properties [7].In order to predict the service properties of the materials and to explore the potential and reserves of their improvement, computational models linking the macroscale (service) In this paper, we present an overview of micromechanical models of nanocrystalline and ultrafine grained materials, their mechanical behaviour, deformation and strength.Composite models, crystal plasticity based models, grain boundary sliding, the effect of non-equilibrium grain boundaries, etc. are reviewed. The main constraints and challenges in the considered models are discussed. Composite models of nanocrystalline metallic materialsThe main structural feature of nanocrystalline and ultrafine grained materials, apart from the small grain sizes, is the high relative volume of grain boundary surface pha...

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“…Strain field zone has also been used to measure shear deformation of the materials. 18,19 However, all these studies have been limited to the surface view due to limited access to the internal deformation zone.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of shear band and shear strain field evolution during blanking of AA6082 sheet

Sonkamble

Dhondapure

Narasimhan

et al. 2019

The Journal of Strain Analysis for Engineering Design

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Interrupted blanking experiments were performed to study the deformation behavior of AA6082 (T6) sheets. An intentional asymmetry was introduced by having the punch and the die of different edge radii. High-resolution microstructural montages of sheet cross-section were used to experimentally measure the shear strain field during each interrupted blanking experiment. This provided a comprehensive experimentally measured spatial–temporal shear strain field for the blanking process. The shear strain was found to be high and localized at the top and bottom surfaces of the sheet which was in contact with the punch and the die. The shear strain was observed to monotonically reduce and get diffused at the interior of the sheet. The strain distribution was also calculated by finite element simulations and found to be in good agreement with the experimentally measured strain distributions. However, the peak strains predicted by the finite element simulations were always marginally lower than those observed by the experimental observations.

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A micromechanical model of the evolution of stress and strain fields in ultrafine-grained metal structures under tension

Cited by 4 publications

References 38 publications

A dislocation-based model for high temperature cyclic viscoplasticity of 9–12Cr steels

A dislocation-based model for high temperature cyclic viscoplasticity of 9–12Cr steels

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Experimental investigation of shear band and shear strain field evolution during blanking of AA6082 sheet

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