Engineering the crack path by controlling the microstructure

Srivastava, Ankit; Osovski, S.; Needleman, A.

doi:10.1016/j.jmps.2016.12.006

Cited by 49 publications

(36 citation statements)

References 56 publications

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“…As in refs. [21,[30][31][32][33], eight point Gaussian integration is used in each twenty-node element for integrating the internal force contributions and twenty-seven point Gaussian integration is used for the element mass matrix. Lumped masses are used so that the mass matrix is diagonal.…”

Section: Unit Cell Finite Element Modelmentioning

confidence: 99%

Dynamics of Necking and Fracture in Ductile Porous Materials

Zheng

N'souglo

Rodríguez-Martínez

et al. 2020

Journal of Applied Mechanics

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bines the effects of loading rate, material properties and unit cell size. Our results show that low initial porosity levels favor necking before fracture, and high initial porosity levels favor fracture before necking, especially at high loading rates where inertia effects delay the onset of necking. The finite element results are also compared with the predictions of linear stability analysis of necking instabilities in porous ductile materials.

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Section: Unit Cell Finite Element Modelmentioning

confidence: 99%

Dynamics of Necking and Fracture in Ductile Porous Materials

Zheng

N'souglo

Rodríguez-Martínez

et al. 2020

Journal of Applied Mechanics

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“…Several physical processes can be viewed as a problem of path selection, for example, flow of a river stream [1] or crack growth in a complex heterogeneous material microstructure [2][3][4]. Although the problems of path selection for flow of a river stream and of crack growth in a heterogeneous material involve very different length-scales, their solutions share common features.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…It has been shown that it is possible to engineer crack paths by controlling the distribution of second phase particles in a ductile matrix to increase the material's crack growth resistance [3]. In [3], the controlled microstructure was char-acterized by various sinusoidal distributions of particles with fixed mean particle spacing. The results presented in [3] indicate that the crack path can be engineered to increase the crack growth resistance by appropriately adding or removing particles that guide the crack path.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Grain Size Distribution on Ductile Intergranular Crack Growth Resistance

Molkeri¹,

Srivastava²,

Osovski³

et al. 2020

Preprint

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The influence of grain size distribution on ductile intergranular crack growth resistance is investigated using full-field microstructure-based finite element calculations and a simpler model based on discrete unit events and graph search. The finite element calculations are carried out for a plane strain slice with planar grains subjected to mode I small-scale yielding conditions. The finite element formulation accounts for finite deformations, and the constitutive relation models the loss of stress carrying capacity due to progressive void nucleation, growth, and coalescence. The discrete unit events are characterized by a set of finite element calculations for crack growth at a single-grain boundary junction. A directed graph of the connectivity of grain boundary junctions and the distances between them is used to create a directed graph in J-resistance space. For a specified grain boundary distribution, this enables crack growth resistance curves to be calculated for all possible crack paths. Crack growth resistance curves are calculated based on various path choice criteria and compared with the results of full-field finite element calculations of the initial boundary value problem. The effect of unimodal and bimodal grain size distributions on intergranular crack growth is considered. It is found that a significant increase in crack growth resistance is obtained if the difference in grain sizes in the bimodal grain size distribution is sufficiently large.

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“…The highly periodic, strenuous, and sinuous crack path for metallic glass is surprising and has not been reported before (details on the geometry and statistics of saw tooth cracks can be found in Figures S5 and S6 in the Supporting Information). Simulations have shown that by tailoring the amplitude and wavelength of this type of saw tooth cracks, fracture toughness can be greatly improved . Furthermore the edge‐on view (Figure c,d) of saw‐tooth cracks reveals a mixture of different types of fracture morphology.…”

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confidence: 98%

“Ductile” Fracture of Metallic Glass Nanolaminates

Fan

Yang

et al. 2017

Adv Materials Inter

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strength and large elastic limit compared with their crystalline counterparts, [1][2][3] but strain (shear) localization and shear softening associated with the rapid propagation of limited shear bands curtail their ductility and hinder their applications as advanced structural materials. [4][5][6] In principle, strain localization/softening can be mitigated by generating profuse shear bands, obstructing shear band propagation, or inhibiting shear band formation by size reduction. In practice, the plasticity and toughness of MGs can be improved intrinsically by optimizing composition, inhomogeneity, and processing history, extrinsically by introducing soft crystalline phase (such as synthesizing crystalamorphous nanolaminates), or reducing sample dimension to nanoscale. [7][8][9][10][11][12] It is worth mentioning that similar to utilizing the size reduction to suppress instability of deformation of metallic glasses, higher stiffness of testing machine can also alleviate the instability. [13,14] Das et al. attributed the intercepted shear bands in CuZrAl bulk MG to structure inhomogeneity. [15] More than 10% tensile strain was achieved for ZrTi-based bulk metallic glass composites by introducing crystalline dendrites. [12] Also at nanoscale, metallic glasses can deform homogeneously without the formation of shear bands [16] and fracture by necking. [11,17] Studies show that when the sample dimension is ≈10 times of the size of STZs (shear transformation zone) or smaller than ≈100 nm, shear band formation can be inhibited in certain metallic glass systems. [14] Fracture morphology, crack path, and fracture mode, however, were not well understood especially at nanometer length scale. Fracture morphology is directly connected to the mechanism of plastic deformation and fracture toughness. Understanding the patterns of fracture surfaces can be beneficial for the selection and design of MGs with better ductility and toughness, and provides guidelines for modeling and simulations on fracture mechanisms.Thin film metallic glasses (TFMGs) are promising candidates for mirco-electromechanical systems applications, as TFMGs may have high hardness and good fatigue resistance, and can be tailored over a wide range of composition. [4,18] With the addition of crystalline phases, ductility/plasticity of TFMG composites (crystal-amorphous nanolaminates) is improved. [19][20][21][22] For instance, Cu 35 nm/amorphous CuZr 5 nm multilayers can reach ≈14% tensile ductility. [23] Due to their extraordinary mechanical properties, TFMGs can also be potentially utilized in stretchable devices in electronic industry. Therefore, tensileMost metallic glasses are brittle as deformation induces low-density sporadic shear bands and severe shear localization proceeding catastrophic failure. Here, it is demonstrated that the introduction of crystalline nanolayers with appropriate dimension can substantially suppress shear localization in metallic glasses, as manifested by ubiquitous ductile dimples in amorphous phase. Furthermore, dimple sizes c...

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Engineering the crack path by controlling the microstructure

Cited by 49 publications

References 56 publications

Dynamics of Necking and Fracture in Ductile Porous Materials

Dynamics of Necking and Fracture in Ductile Porous Materials

Influence of Grain Size Distribution on Ductile Intergranular Crack Growth Resistance

“Ductile” Fracture of Metallic Glass Nanolaminates

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