On flaw tolerance of nacre: a theoretical study

Shao, Yue; Zhao, Hongping; Feng, Xi‐Qiao

doi:10.1098/rsif.2013.1016

Cited by 62 publications

(22 citation statements)

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“…Adopting the self-similarity assumption of microstructure, Zuo and Wei [36] investigated the trans-scale mechanical property of the hierarchical structure theoretically, by using the modified shear-lag model. In order to interpret the huge property difference between nanoscale and macroscopic scale, more recently, damage, flaw tolerances, and hierarchical features in the nacre structure were investigated [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Mineralized biological materials, such as shells, bone, and teeth, have been attracting a great deal of attention during the last several decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], specifically, in more recent years [1][2][3][4][5][6], due to their unique microstructures and superior mechanical properties. The limnetic shell is a typical example of such biomaterial; it consists of nacreous and prismatic structures which display unique hierarchical features.…”

Section: Introductionmentioning

confidence: 99%

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Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

Song

Fan

et al. 2015

Acta Mech Sin

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In the present research, hierarchical structure observation and mechanical property characterization for a type of biomaterial are carried out. The investigated biomaterial is Hyriopsis cumingii, a typical limnetic shell, which consists of two different structural layers, a prismatic "pillar" structure and a nacreous "brick and mortar" structure. The prismatic layer looks like a "pillar forest" with variationsection pillars sized on the order of several tens of microns. The nacreous material looks like a "brick wall" with bricks sized on the order of several microns. Both pillars and bricks are composed of nanoparticles. The mechanical properties of the hierarchical biomaterial are measured by using the nanoindentation test. Hardness and modulus are measured for both the nacre layer and the prismatic layer, respectively. The nanoindentation size effects for the hierarchical structural materials are investigated experimentally. The results show that the prismatic nanostructured material has a higher stiffness and hardness than the nacre nanostructured material. In addition, the nanoindentation size effects for the hierarchical structural materials are described theoretically, by using the trans-scale mechanics theory considering both strain gradient effect and the surface/interface effect. The modeling results are consistent with experimental ones.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

Song

Fan

et al. 2015

Acta Mech Sin

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“…Interface 12: 20140855 nacre and proposed a discontinuous crack-bridging model for fracture toughness analysis of nacre [58]. The effect of pre-existing structural defects was investigated in the crackbridging based model in another study by Shao et al [59]. More recently, Begley et al [60] studied the brick and mortar structure and proposed a model to guide the development of these composites.…”

Section: Introductionmentioning

confidence: 99%

Toughening mechanisms in bioinspired multilayered materials

Askarinejad

Rahbar

2015

J. R. Soc. Interface.

125

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Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mechanical performance. A micromechanical model for multilayered biological materials is proposed to simulate their mechanical deformation and toughening mechanisms. The fundamental hypothesis of the model is the inclusion of nanoscale pillars with near theoretical strength (s th E/30). It is also assumed that pillars and asperities confine the organic matrix to the proximity of the platelets, and, hence, increase their stiffness, since it has been previously shown that the organic matrix behaves more stiffly in the proximity of mineral platelets. The modelling results are in excellent agreement with the available experimental data for abalone nacre. The results demonstrate that the aragonite platelets, pillars and organic matrix synergistically affect the stiffness of nacre, and the pillars significantly contribute to the mechanical performance of nacre. It is also shown that the roughness induced interactions between the organic matrix and aragonite platelet, represented in the model by asperity elements, play a key role in strength and toughness of abalone nacre. The highly nonlinear behaviour of the proposed multilayered material is the result of distributed deformation in the nacre-like structure due to the existence of nano-asperities and nanopillars with near theoretical strength. Finally, tensile toughness is studied as a function of the components in the microstructure of nacre.

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“…196 In particular, its characteristic "brick9and9mortar" structure 7 is understood to play the key role in developing a high resistance to defects; it consists of 95 % brittle inorganic aragonite (CaCO 3 ) building blocks, around 2009900 nm thick and 59 8 Jm wide (aspect ratio from 7915), 8 "glued" together by a soft chitin9containing organic framework. This organic layer is around 209 30 nm thick 9 and makes up the remaining 5 % of the structure.…”

mentioning

confidence: 99%

“…The aspect ratio of the platelets has been identified as a critical parameter. 7,22924 High stiffness and high strength are achieved by increasing platelet anisotropy. 18,22 However, the toughening mechanisms of nacre only occur below a critical aspect ratio, which allows pull9out and subsequent sliding of the platelets.…”

mentioning

confidence: 99%

Nacre-nanomimetics: Strong, Stiff, and Plastic

Luca¹,

Menzel²,

Blaker³

et al. 2015

ACS Appl. Mater. Interfaces

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*Address correspondence to m.shaffer@imperial.ac.uk , The bricks and mortar in the classic structure of nacre have characteristic geometry, aspect ratios and relative proportions; these key parameters can be retained whilst scaling down the absolute length scale by more than one order of magnitude. The results shed light on fundamental scaling behavior and provide new opportunities for high performance, yet ductile, lightweight nanocomposites. Reproducing the toughening mechanisms of nacre at smaller length scales allows a greater volume of interface per unit volume whilst simultaneously increasing the intrinsic properties of the inorganic constituents. Layer9by9Layer (LbL) assembly of poly (sodium 49styrene sulfonate) (PSS) polyelectrolyte and well9defined [Mg 2 Al(OH) 6 ]CO 3 .nH 2 O layered double hydroxide (LDH) platelets produces a dense, oriented, high inorganic content (~90 wt%) nanostructure resembling natural nacre, but at a shorter length scale. The smaller building blocks enable the (self9) assembly of a higher quality nanostructure than conventional mimics, leading to improved mechanical properties, approaching those of natural nacre, whilst allowing for substantial plastic deformation. Both strain hardening and crack deflection mechanisms were observed by scanning electron microscopy (SEM) during nanoindentation. The best properties emerge from an ordered nanostructure, generated using regular platelets, with narrow size dispersion.Like many natural composites, the structure of nacre, found in the inner part of some mollusk shells, is a complex hierarchical structure organized over multiple hierarchical levels leading to coupled toughening mechanisms. 196 In particular, its characteristic "brick9and9mortar" structure 7 is understood to play the key role in developing a high resistance to defects; it consists of 95 % brittle inorganic aragonite (CaCO 3 ) building blocks, around 2009900 nm thick and 59 8 Jm wide (aspect ratio from 7915), 8 "glued" together by a soft chitin9containing organic framework. This organic layer is around 209 30 nm thick 9 and makes up the remaining 5 % of the structure. The combination of a small fraction of organic phase along with this specific three9 dimensional architecture leads to exceptional mechanical properties, including high toughness (≈ 1.24 kJ.m 92 ), strength (≈ 140 MPa) and stiffness (E ≈ 60 GPa). 10,11 When loaded, the "bricks" have the ability to slide over one another within the organic phase and eventually interlock 12,13 via a range of possible mechanisms, 14 leading to strain hardening. 14,15 In addition, when a crack initiates from a defect within the nacre structure, multiple crack 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 deflections occur at the building block interfaces. 16 According to the Griffith criterion, the fracture strength of pure aragonite platelets can...

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On flaw tolerance of nacre: a theoretical study

Cited by 62 publications

References 53 publications

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

Toughening mechanisms in bioinspired multilayered materials

Nacre-nanomimetics: Strong, Stiff, and Plastic

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