List of Journal Publications
2019
4.
Shabir, Z., der Giessen, E. Van, Duarte, C. A., Simone, A.
On the applicability of linear elastic fracture mechanics scaling relations in the analysis of intergranular fracture of brittle polycrystals Journal Article
In: INTERNATIONAL JOURNAL OF FRACTURE, vol. 220, no. 2, pp. 205–219, 2019.
Abstract | BibTeX | Tags: Brittle fracture, generalized finite element method, Linear elastic fracture mechanics, polycrystals, Scaling | Links:
@article{Shabir2019,
title = {On the applicability of linear elastic fracture mechanics scaling relations in the analysis of intergranular fracture of brittle polycrystals},
author = {Z. Shabir and E. Van der Giessen and C. A. Duarte and A. Simone},
doi = {10.1007/s10704-019-00381-x},
year = {2019},
date = {2019-01-01},
journal = {INTERNATIONAL JOURNAL OF FRACTURE},
volume = {220},
number = {2},
pages = {205–219},
publisher = {Springer},
abstract = {Crack propagation in polycrystalline specimens is studied by means of a generalized finite element method with linear elastic isotropic grains and cohesive grain boundaries. The corresponding mode-I intergranular cracks are characterized using a grain boundary brittleness criterion that depends on cohesive law parameters and average grain boundary length. It is shown that load–displacement curves for specimens with the same microstructure and for various cohesive law parameters can be obtained from a master load–displacement curve by means of simple linear elastic fracture mechanics scaling relations. This property is a consequence of the independence of intergranular crack paths from cohesive law parameters. Perfect scaling is obtained for cases characterized by the same grain boundary brittleness number, irrespective of its value, whereas scaling is approximated for cases with different but relatively large values of the grain boundary brittleness number. The former case corresponds to grain boundary traction profiles that are identical apart from a scale factor; in the latter case, a large grain boundary brittleness number implies similar, apart from a scale factor, traction profiles. By exploiting this property, it is demonstrated that computationally expensive simulations can be avoided above a certain grain boundary brittleness threshold value.},
keywords = {Brittle fracture, generalized finite element method, Linear elastic fracture mechanics, polycrystals, Scaling},
pubstate = {published},
tppubtype = {article}
}
Crack propagation in polycrystalline specimens is studied by means of a generalized finite element method with linear elastic isotropic grains and cohesive grain boundaries. The corresponding mode-I intergranular cracks are characterized using a grain boundary brittleness criterion that depends on cohesive law parameters and average grain boundary length. It is shown that load–displacement curves for specimens with the same microstructure and for various cohesive law parameters can be obtained from a master load–displacement curve by means of simple linear elastic fracture mechanics scaling relations. This property is a consequence of the independence of intergranular crack paths from cohesive law parameters. Perfect scaling is obtained for cases characterized by the same grain boundary brittleness number, irrespective of its value, whereas scaling is approximated for cases with different but relatively large values of the grain boundary brittleness number. The former case corresponds to grain boundary traction profiles that are identical apart from a scale factor; in the latter case, a large grain boundary brittleness number implies similar, apart from a scale factor, traction profiles. By exploiting this property, it is demonstrated that computationally expensive simulations can be avoided above a certain grain boundary brittleness threshold value.
2011
3.
Shabir, Z., der Giessen, E. Van, Duarte, C. A., Simone, A.
The role of cohesive properties on intergranular crack propagation in brittle polycrystals Journal Article
In: MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, vol. 19, no. 3, 2011.
Abstract | BibTeX | Tags: brittle failure, cracks, GFEM, polycrystals | Links:
@article{Shabir2011,
title = {The role of cohesive properties on intergranular crack propagation in brittle polycrystals},
author = {Z. Shabir and E. Van der Giessen and C. A. Duarte and A. Simone},
doi = {10.1088/0965-0393/19/3/035006},
year = {2011},
date = {2011-01-01},
journal = {MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING},
volume = {19},
number = {3},
abstract = {We analyze intergranular brittle cracking of polycrystalline aggregates by means of a generalized finite element method for polycrystals with cohesive grain boundaries and linear elastic grains. Many random realizations of a polycrystalline topology are considered and it is shown that the resulting crack paths are insensitive to key cohesive law parameters such as maximum cohesive strength and critical fracture energy. Normal and tangential contributions to the dissipated energy are thoroughly investigated with respect to mesh refinement, cohesive law parameters and randomness of the underlying polycrystalline microstructure.},
keywords = {brittle failure, cracks, GFEM, polycrystals},
pubstate = {published},
tppubtype = {article}
}
We analyze intergranular brittle cracking of polycrystalline aggregates by means of a generalized finite element method for polycrystals with cohesive grain boundaries and linear elastic grains. Many random realizations of a polycrystalline topology are considered and it is shown that the resulting crack paths are insensitive to key cohesive law parameters such as maximum cohesive strength and critical fracture energy. Normal and tangential contributions to the dissipated energy are thoroughly investigated with respect to mesh refinement, cohesive law parameters and randomness of the underlying polycrystalline microstructure.
2010
2.
Shishvan, Siamak Soleymani, Nicola, L., Giessen, Erik Van Der
Bauschinger effect in unpassivated freestanding thin films Journal Article
In: JOURNAL OF APPLIED PHYSICS, vol. 107, no. 9, 2010.
Abstract | BibTeX | Tags: Bauschinger effect, discrete dislocation plasticity, polycrystals | Links:
@article{Shishvan2010,
title = {Bauschinger effect in unpassivated freestanding thin films},
author = {Siamak Soleymani Shishvan and L. Nicola and Erik Van Der Giessen},
doi = {10.1063/1.3407505},
year = {2010},
date = {2010-01-01},
journal = {JOURNAL OF APPLIED PHYSICS},
volume = {107},
number = {9},
publisher = {AMER INST PHYSICS},
abstract = {Two-dimensional (2D) discrete dislocation plasticity simulations are carried out to investigate the Bauschinger effect (BE) in freestanding thin films. The BE in plastic flow of polycrystalline materials is generally understood to be caused by inhomogeneous deformation during loading, leading to residual stress upon unloading. This inhomogeneity can be caused by dislocation pile-ups, variations in texture, grain orientations, and grain size. To study the BE, columnar-grained films as well as films with multiple grains across the thickness are considered. The film is modeled in a 2D framework by a unit cell consisting of an array of grains with different orientation. In order to capture the interaction among grains, we motivate and explore the use of an affine deformation assumption on the grain level to mimic the three-dimensional geometry in this framework. It is shown that the dispersion of grain size in a film together with the size-dependence of yield strength leads to significant BEs in bare films. Quantitative comparison of simulations with experimental data is provided.},
keywords = {Bauschinger effect, discrete dislocation plasticity, polycrystals},
pubstate = {published},
tppubtype = {article}
}
Two-dimensional (2D) discrete dislocation plasticity simulations are carried out to investigate the Bauschinger effect (BE) in freestanding thin films. The BE in plastic flow of polycrystalline materials is generally understood to be caused by inhomogeneous deformation during loading, leading to residual stress upon unloading. This inhomogeneity can be caused by dislocation pile-ups, variations in texture, grain orientations, and grain size. To study the BE, columnar-grained films as well as films with multiple grains across the thickness are considered. The film is modeled in a 2D framework by a unit cell consisting of an array of grains with different orientation. In order to capture the interaction among grains, we motivate and explore the use of an affine deformation assumption on the grain level to mimic the three-dimensional geometry in this framework. It is shown that the dispersion of grain size in a film together with the size-dependence of yield strength leads to significant BEs in bare films. Quantitative comparison of simulations with experimental data is provided.
2006
1.
Simone, A., Duarte, C. A., der Giessen, E. Van
A Generalized Finite Element Method for polycrystals with discontinuous grain boundaries Journal Article
In: INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, vol. 67, no. 8, pp. 1122–1145, 2006.
Abstract | BibTeX | Tags: Extended Finite Element Method, generalized finite element method, Grain boundary sliding, Partition of unity, polycrystals | Links:
@article{Simone2006,
title = {A Generalized Finite Element Method for polycrystals with discontinuous grain boundaries},
author = {A. Simone and C. A. Duarte and E. Van der Giessen},
doi = {10.1002/nme.1658},
year = {2006},
date = {2006-01-01},
journal = {INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING},
volume = {67},
number = {8},
pages = {1122–1145},
abstract = {We present a Generalized Finite Element Method for the analysis of polycrystals with explicit treatment of grain boundaries. Grain boundaries and junctions, understood as loci of possible displacement discontinuity, are inserted into finite elements by exploiting the partition of unity property of finite element shape functions. Consequently, the finite element mesh does not need to conform to the polycrystal topology. The formulation is outlined and a numerical example is presented to demonstrate the potential and accuracy of the approach. The proposed methodology can also be used for branched and intersecting cohesive cracks, and comparisons are made to a related approach (Int. J. Numer. Meth. Engng. 2000; 48:1741).},
keywords = {Extended Finite Element Method, generalized finite element method, Grain boundary sliding, Partition of unity, polycrystals},
pubstate = {published},
tppubtype = {article}
}
We present a Generalized Finite Element Method for the analysis of polycrystals with explicit treatment of grain boundaries. Grain boundaries and junctions, understood as loci of possible displacement discontinuity, are inserted into finite elements by exploiting the partition of unity property of finite element shape functions. Consequently, the finite element mesh does not need to conform to the polycrystal topology. The formulation is outlined and a numerical example is presented to demonstrate the potential and accuracy of the approach. The proposed methodology can also be used for branched and intersecting cohesive cracks, and comparisons are made to a related approach (Int. J. Numer. Meth. Engng. 2000; 48:1741).
