The stress state close to a crack tip shielded by a dislocation array

Lii, Mirng-Ji

doi:10.1016/s0036-9748(88)80283-7

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…With the nearest tip-emitted dislocation being pushed away by the crack-tip stress field, this DFZ becomes a critical length scale in modelling fracture resistance. These and similar cracktip source models [74][75][76][77][78][79][80][81] were generally directed towards cleavage phenomena in relatively brittle materials. Later on they were applied to layered structures [75] and thin films [81].…”

Section: Mesoscopic Modelling (Multi-scale)mentioning

confidence: 99%

“…Also, d (I ) j is related to the Burgers vector of magnitude b (I ) i b (I ) i = B ij d (I ) j (A13) and the matrices B, L, M and P are functions of the elastic constants. In the computation, presented elsewhere [76,77] the sample material was iron for which the elastic constants are C 11 = 24.2, C 12 = 14.65 and C 44 = 11.2 in units of 10 4 MPa. Certain restrictions were considered in performing the simulations.…”

Section: Appendix a Pull-off Forces For Clean Metal Contactsmentioning

confidence: 99%

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Physics of adhesion

Gerberich¹,

Cordill²

2006

Rep. Prog. Phys.

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Adhesion physics was relegated to the lowest echelons of academic pursuit until the advent of three seemingly disconnected events. The first, atomic force microscopy (AFM), eventually allowed fine-scale measurement of adhesive point contacts. The second, large-scale computational materials science, now permits both hierarchical studies of a few thousand atoms from first principles or of billions of atoms with less precise interatomic potentials. The third is a microelectronics industry push towards the nanoscale which has provided the driving force for requiring a better understanding of adhesion physics. In the present contribution, an attempt is made at conjoining these separate events into an updating of how theoretical and experimental approaches are providing new understanding of adhesion physics. While all material couples are briefly considered, the emphasis is on metal/semiconductor and metal/ceramic interfaces. Here, adhesion energies typically range from 1 to 100 J m −2 where the larger value is considered a practical work of adhesion. Experimental emphasis is on thin-film de-adhesion for 10 to 1000 nm thick films. For comparison, theoretical approaches from first principles quantum mechanics to embedded atom methods used in multi-scale modelling are utilized.

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Section: Mesoscopic Modelling (Multi-scale)mentioning

confidence: 99%

Section: Appendix a Pull-off Forces For Clean Metal Contactsmentioning

confidence: 99%

Physics of adhesion

Gerberich¹,

Cordill²

2006

Rep. Prog. Phys.

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“…The current model [4][5][6][7][8][9] followed the extended formulation by Atkinson and Clements [8], Lii et al [5] and Lii and Gerberich [9] superdislocation model. Basically, it has been founded on the crack tip dislocations interaction following a systematic theoretical/experimental program.…”

Section: Discussionmentioning

confidence: 99%

“…Regarding simulations, more is discussed concerning quasi-continuum models. Here, mainly the cracktip dislocation emission model was argued following Atkinson and Clements procedure [8] and also Lii and Gerberich [9] with a different dislocations arrangement.…”

Section: Discussionmentioning

confidence: 99%

Small volume mechanical response insights: revealed contributions in advancing high mechanical performance

Katz¹

2008

WIT Transactions on the Built Environment

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Three factors have emerged in order to upgrade the understanding of ultra small volume mechanical behavior in terms of multi-scale analysis and models. Firstly, the global/local approach based on physical models formulation, secondly, the continuous effort vis-à-vis microelectronic requirements for effective material performance and thirdly, the remarkable progress in experimental capacity that requires ultra-fine features visualization and measurements beside computational abilities. The current study is centered on iron based silicon polycrystalline alloy and the mechanical characterization of 20-50 nm silicon particles by contact methodology at ambient temperatures. In both, either monotonic or cyclic, mechanical properties were size dependent. Regarding the iron-silicon single crystals, mini compact tension specimens enabled the tracking of crack-tip dislocation emissions and their interactions in order to deepen the shielding potential exploration. Deformation/fracture processes and ductile-brittle fracture models could be elaborated. The aforementioned examples in elastic-plastic crystals were still intended to emphasize conceptual insights. Higher mechanical performance is examined from emerging localized findings and nanomechanical response analysis.

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“…[85][86][87] They can include atomistic, microstructural and continuum plasticity in a single simulation. These and similar crack-tip source models [88][89][90][91] were generally directed towards cleavage phenomena in relatively brittle materials. For the adhesion subject at hand, only a few attempts at adapting this type of modelling have been made.…”

Section: Mesoscopic Modellingmentioning

confidence: 99%