Discrete dislocation analysis of the wedge indentation of polycrystals

Widjaja, Andreas; Giessen, E. van der; Needleman, A.

doi:10.1016/j.actamat.2007.07.053

Cited by 22 publications

(9 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, as the indentation depth and the stress acting on the GB gradually increase, 19 the dislocations are transmitted through the GB and leave dislocation debris (red lines in Fig. 8(b)) on the GB once the resolved shear stress acting on a trapped dislocation reaches the critical value for dislocation transmission, Eq.…”

Section: Pop-in Eventmentioning

confidence: 99%

“…Indentation size effects and influences of indenter shape were investigated by two-dimensional DDD simulations on single crystals [16,17], by using the method introduced by Needleman and Van der Giessen [18] which couples DDD with FEM to evaluate dislocation interactions in terms of surface-corrected infinite-body dislocation stress fields. Two-dimensional DDD simulations on polycrystals also captured the effects of grain size and indentation depth on indentation response [19,20]. The first three-dimensional (3D) DDD simulation of nanoindentation was conducted by Fivel et al [12].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Grain boundary effect on nanoindentation: A multiscale discrete dislocation dynamics model

Zhang

et al. 2019

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

Nanoindentation is a convenient method to investigate the mechanical properties of materials on small scales by utilizing low loads and small indentation depths.However, the effect of grain boundaries (GB) on the nanoindentation response remains unclear and needs to be studied by investigating in detail the interactions between dislocations and GBs during nanoindentation. In the present work, we employ a threedimensional multiscale modeling framework, which couples three-dimensional discrete dislocation dynamics (DDD) with the Finite Element method (FEM) to investigate GB effects on the nanoindentation behavior of an aluminum bicrystal. The interaction between dislocations and GB is physically modeled in terms of a penetrable GB, where piled-up dislocations can penetrate through the GB and dislocation debris at GBs can emit full dislocations into grains. In the simulation, we confirmed two experimentally observed phenomena, namely, pop-in events and the dependence of indentation hardness on the distance from GB. Two pop-in events were observed, of which the initial pop-in event is correlated with the activation and multiplication of dislocations, while the GB pop-in event results from dislocation transmission through the GB. By changing the distance between the indenter and GB, the simulation shows that the 2 indentation hardness increases with decreasing GB-indenter distance. A quantitative model has been formulated which relates the dependency of indentation hardness on indentation depth and on GB-indenter distance to the back stress created by piled-up geometrically necessary dislocations in the plastic zone and to the additional constraint imposed by the GB on the plastic zone size.

show abstract

Section: Pop-in Eventmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Grain boundary effect on nanoindentation: A multiscale discrete dislocation dynamics model

Zhang

et al. 2019

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

show abstract

“…The nominal contact size, 𝐴 𝑁 ≡ 2𝑑/ tan(𝛼), and actual contact size 𝐴, which is defined as the distance between the rightmost and leftmost nodes within the contact, were used, as in Ref. [46]. The nominal and actual contact sizes are in general different, and the difference depends on the degree of pile-up or sink-in experienced during indentation.…”

Section: Problem Definitionmentioning

confidence: 99%

A new hardness formula incorporating the effect of source density on indentation response: A discrete dislocation plasticity analysis

Balint

Dini

2019

Surface and Coatings Technology

View full text Add to dashboard Cite

Planar discrete dislocation plasticity (DDP) calculations that simulate thin single crystal films bonded to a rigid substrate indented by a rigid wedge are performed for different values of film thickness and dislocation source density. As in prior studies, an indentation size effect (ISE) is observed when indentation depth is sufficiently small relative to the film thickness. The dependence of the ISE on dislocation source density is quantified in this study, and a modified form of the scaling law for the dependence of hardness on indentation depth, first derived by Nix and Gao, is proposed, which is valid over the entire range of indentation depths and correlates the length scale parameter with the average dislocation source spacing. Nanoindentation experimental data from the literature are fitted using this formula, which further verifies the proposed scaling of indentation pressure on dislocation source density.

show abstract

“…Balint et al (2006) carried out a 2D-DDD modeling of indentation of a single crystal film bonded on a rigid substrate by a rigid wedge indenter, showing significant influences of film thickness on the transition from size-dependent hardness to size-independent continuum hardness. Widjaja et al systematically modeled the wedge indentation on a single crystal material (Widjaja et al, 2007a) and a polycrystalline material (Widjaja et al, 2007b), investigated the size effects from indenter depth, wedge angle, as well as grain size. However, it is well known that the indenter tip in actual experiments is usually curved.…”

Section: Introductionmentioning

confidence: 99%

Cylindrical nano-indentation on metal film/elastic substrate system with discrete dislocation plasticity analysis: A simple model for nano-indentation size effect

Ouyang

Huang

et al. 2010

International Journal of Solids and Structures

View full text Add to dashboard Cite

a b s t r a c tThe cylindrical nano-indentation on metal film/elastic substrate is computationally studied using twodimensional discrete dislocation plasticity combined with the commercial software ANSYS Ò , with a focus on the storage volume for geometrically necessary dislocations (GNDs) inside the films and the nanoindentation size effect (NISE). Our calculations show that almost all GNDs are stored in a rectangular area determined by the film thickness and the actual contact width. The variations of indentation contact width with indentation depth for various film thicknesses and indenter radii are fitted by an exponential relation, and then the GND density underneath the indenter is estimated. Based on the Taylor dislocation model and Tabor formula, a simple model for the dependence of the nano-indentation hardness of the film/substrate system on the indentation depth, the indenter radius and the film thickness is established, showing a good agreement with the present numerical results.Ó

show abstract

Discrete dislocation analysis of the wedge indentation of polycrystals

Cited by 22 publications

References 17 publications

Grain boundary effect on nanoindentation: A multiscale discrete dislocation dynamics model

Grain boundary effect on nanoindentation: A multiscale discrete dislocation dynamics model

A new hardness formula incorporating the effect of source density on indentation response: A discrete dislocation plasticity analysis

Cylindrical nano-indentation on metal film/elastic substrate system with discrete dislocation plasticity analysis: A simple model for nano-indentation size effect

Contact Info

Product

Resources

About