List of Journal Publications
2022
3.
Aramfard, Mohammad, RAFOLS, Francisco PEREZ, Nicola, L.
A 2D dual-scale method to address contact problems Journal Article
In: TRIBOLOGY INTERNATIONAL, vol. 171, 2022.
Abstract | BibTeX | Tags: contact mechanics, friction, Indentation, Multiscale modeling | Links:
@article{Aramfard2022,
title = {A 2D dual-scale method to address contact problems},
author = {Mohammad Aramfard and Francisco PEREZ RAFOLS and L. Nicola},
doi = {10.1016/j.triboint.2022.107509},
year = {2022},
date = {2022-01-01},
journal = {TRIBOLOGY INTERNATIONAL},
volume = {171},
publisher = {ELSEVIER SCI LTD},
abstract = {A seamless 2D dual-scale computational scheme is developed to study contact problems. The model consists of an atomistic domain close to the contact, coupled with an elastic continuum domain away from the contact. The atomistic formulation provides a description of the contact interaction through interatomic potentials and permits to capture atomic wear and defect formation in the contact region. The fields in the continuum domain are calculated by an efficient FFT-based Green's function method. The novel scheme is validated against full atomistic simulations and applied to study the effect of adhesion on the scratching of a rough copper surface by a rigid smooth spherical tip.},
keywords = {contact mechanics, friction, Indentation, Multiscale modeling},
pubstate = {published},
tppubtype = {article}
}
A seamless 2D dual-scale computational scheme is developed to study contact problems. The model consists of an atomistic domain close to the contact, coupled with an elastic continuum domain away from the contact. The atomistic formulation provides a description of the contact interaction through interatomic potentials and permits to capture atomic wear and defect formation in the contact region. The fields in the continuum domain are calculated by an efficient FFT-based Green's function method. The novel scheme is validated against full atomistic simulations and applied to study the effect of adhesion on the scratching of a rough copper surface by a rigid smooth spherical tip.
2021
2.
Dokkum, J. S. Van, Perez-Rafols, F., Dorogin, L., Nicola, L.
On the retraction of an adhesive cylindrical indenter from a viscoelastic substrate Journal Article
In: TRIBOLOGY INTERNATIONAL, vol. 164, 2021.
Abstract | BibTeX | Tags: Adhesion contact, Boundary Element Method, Indentation, Line contact | Links:
@article{VanDokkum2021,
title = {On the retraction of an adhesive cylindrical indenter from a viscoelastic substrate},
author = {J. S. Van Dokkum and F. Perez-Rafols and L. Dorogin and L. Nicola},
doi = {10.1016/j.triboint.2021.107234},
year = {2021},
date = {2021-01-01},
journal = {TRIBOLOGY INTERNATIONAL},
volume = {164},
publisher = {Elsevier Ltd},
abstract = {The retraction of a cylindrical rigid indenter from a viscoelastic substrate is studied by means of an efficient Green's function method. Hysteresis is observed in the load to area relationship in accordance with experimental results. Although our model relaxes many assumptions posed by LEFM-based analytical theories, the results fall between the limits, at high and low retraction velocities, predicted by the theories. Approaching the high velocity instantaneous limit requires, however, very high velocities or Maugis parameter. The work of adhesion is found to change during retraction. A non-dimensional parameter is proposed to estimate the effect of viscoelasticity in adhesive hysteresis.},
keywords = {Adhesion contact, Boundary Element Method, Indentation, Line contact},
pubstate = {published},
tppubtype = {article}
}
The retraction of a cylindrical rigid indenter from a viscoelastic substrate is studied by means of an efficient Green's function method. Hysteresis is observed in the load to area relationship in accordance with experimental results. Although our model relaxes many assumptions posed by LEFM-based analytical theories, the results fall between the limits, at high and low retraction velocities, predicted by the theories. Approaching the high velocity instantaneous limit requires, however, very high velocities or Maugis parameter. The work of adhesion is found to change during retraction. A non-dimensional parameter is proposed to estimate the effect of viscoelasticity in adhesive hysteresis.
2007
1.
Nicola, L., Bower, A. F., Kim, K. -S., Needleman, A., der Giessen, E. Van
Surface versus bulk nucleation of dislocations during contact Journal Article
In: JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, vol. 55, no. 6, pp. 1120–1144, 2007.
Abstract | BibTeX | Tags: contact mechanics, discrete dislocation plasticity, Indentation, Residual stress, Size effect | Links:
@article{Nicola2007,
title = {Surface versus bulk nucleation of dislocations during contact},
author = {L. Nicola and A. F. Bower and K. -S. Kim and A. Needleman and E. Van der Giessen},
doi = {10.1016/j.jmps.2006.12.005},
year = {2007},
date = {2007-01-01},
journal = {JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS},
volume = {55},
number = {6},
pages = {1120–1144},
abstract = {The indentation of single crystals by a periodic array of flat rigid contacts is analyzed using discrete dislocation plasticity. Plane strain analyses are carried out with the dislocations all of edge character and modeled as line singularities in a linear elastic solid. The limiting cases of frictionless and perfectly sticking contacts are considered. The effects of contact size, dislocation source density, and dislocation obstacle density and strength on the evolution of the mean indentation pressure are explored, but the main focus is on contrasting the response of crystals having dislocation sources on the surface with that of crystals having dislocation sources in the bulk. When there are only bulk sources, the mean contact pressure for sufficiently large contacts is independent of the friction condition, whereas for sufficiently small contact sizes, there is a significant dependence on the friction condition. When there are only surface dislocation sources the mean contact pressure increases much more rapidly with indentation depth than when bulk sources are present and the mean contact pressure is very sensitive to the strength of the obstacles to dislocation glide. Also, on unloading a layer of tensile residual stress develops when surface dislocation sources dominate.},
keywords = {contact mechanics, discrete dislocation plasticity, Indentation, Residual stress, Size effect},
pubstate = {published},
tppubtype = {article}
}
The indentation of single crystals by a periodic array of flat rigid contacts is analyzed using discrete dislocation plasticity. Plane strain analyses are carried out with the dislocations all of edge character and modeled as line singularities in a linear elastic solid. The limiting cases of frictionless and perfectly sticking contacts are considered. The effects of contact size, dislocation source density, and dislocation obstacle density and strength on the evolution of the mean indentation pressure are explored, but the main focus is on contrasting the response of crystals having dislocation sources on the surface with that of crystals having dislocation sources in the bulk. When there are only bulk sources, the mean contact pressure for sufficiently large contacts is independent of the friction condition, whereas for sufficiently small contact sizes, there is a significant dependence on the friction condition. When there are only surface dislocation sources the mean contact pressure increases much more rapidly with indentation depth than when bulk sources are present and the mean contact pressure is very sensitive to the strength of the obstacles to dislocation glide. Also, on unloading a layer of tensile residual stress develops when surface dislocation sources dominate.
