iMechanica - material length scale
https://imechanica.org/taxonomy/term/10345
enGradient plasticity crack tip characterization by means of the extended finite element method (MATLAB code included)
https://imechanica.org/node/21101
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/3513">strain gradient plasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/5089">extended finite element method</a></div><div class="field-item even"><a href="/taxonomy/term/11594">Crack tip fields</a></div><div class="field-item odd"><a href="/taxonomy/term/10345">material length scale</a></div><div class="field-item even"><a href="/taxonomy/term/1417">Matlab</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>I hope some of you may find this work interesting, the X-FEM non-linear code developed (incorporating linear elasticity, J2 plasticity, and Strain Gradient Plasticity) can be downloaded from <a title="www.empaneda.com/codes" href="http://www.empaneda.com/codes/">www.empaneda.com/codes</a></p>
<p>Gradient plasticity crack tip characterization by means of the extended finite element method</p>
<p>Emilio Martínez-Pañeda, Sundararajan Natarajan, Stéphane Bordas</p>
<p>Computational Mechanics (2017)</p>
<p><a href="https://link.springer.com/article/10.1007/s00466-017-1375-6">https://link.springer.com/article/10.1007/s00466-017-1375-6</a></p>
<p>Strain gradient plasticity theories are being widely used for fracture assessment, as they provide a richer description of crack tip fields by incorporating the influence of geometrically necessary dislocations. Characterizing the behavior at the small scales involved in crack tip deformation requires, however, the use of a very refined mesh within microns to the crack. In this work, a novel and efficient gradient-enhanced numerical framework is developed by means of the extended finite element method (X-FEM). A mechanism-based gradient plasticity model is employed and the approximation of the displacement field is enriched with the stress singularity of the gradient-dominated solution. Results reveal that the proposed numerical methodology largely outperforms the standard finite element approach. The present work could have important implications on the use of microstructurally-motivated models in large scale applications. The non-linear X-FEM code developed in MATLAB can be downloaded from <a href="http://www.empaneda.com/codes">www.empaneda.com/codes</a>.</p>
</div></div></div>Sun, 02 Apr 2017 09:18:12 +0000Emilio Martínez Pañeda21101 at https://imechanica.orghttps://imechanica.org/node/21101#commentshttps://imechanica.org/crss/node/21101Modeling damage and fracture within strain-gradient plasticity
https://imechanica.org/node/17975
<div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/10343">Strain-gradient plasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/10344">Taylor dislocation model</a></div><div class="field-item even"><a href="/taxonomy/term/10345">material length scale</a></div><div class="field-item odd"><a href="/taxonomy/term/10346">crack-tip fields</a></div><div class="field-item even"><a href="/taxonomy/term/9046">Finite Element Analysis (FEA)</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>I hope some of you (especially those working on fracture and damage modeling) may find this work interesting:</p>
<p>Modeling damage and fracture within strain-gradient plasticity</p>
<p><a href="http://www.sciencedirect.com/science/article/pii/S0020768315000505#">http://www.sciencedirect.com/science/article/pii/S0020768315000505#</a></p>
<p><span>In this work, the influence of the plastic size effect on the fracture process of metallic materials is numerically analyzed using the strain-gradient plasticity (SGP) theory established from the Taylor dislocation model. Since large deformations generally occur in the vicinity of a crack, the numerical framework of the chosen SGP theory is developed for allowing large strains and rotations. The material model is implemented in a commercial finite element (FE) code by a user subroutine, and crack-tip fields are evaluated thoroughly for both infinitesimal and finite deformation theories by a boundary-layer formulation. An extensive parametric study is conducted and differences in the stress distributions ahead of the crack tip, as compared with conventional plasticity, are quantified. As a consequence of the strain-gradient contribution to the work hardening of the material, FE results show a significant increase in the magnitude and the extent of the differences between the stress fields of SGP and conventional plasticity theories when finite strains are considered. Since the distance from the crack tip at which the strain gradient significantly alters the stress field could be one order of magnitude higher when large strains are considered, results reveal that the plastic size effect could have important implications in the modelization of several damage mechanisms where its influence has not yet been considered in the literature.</span></p>
</div></div></div>Wed, 25 Feb 2015 17:16:46 +0000Emilio Martínez Pañeda17975 at https://imechanica.orghttps://imechanica.org/node/17975#commentshttps://imechanica.org/crss/node/17975Error | iMechanica