List of Journal Publications
2017
2.
Malagù, M., Goudarzi, M., Lyulin, A., Benvenuti, E., Simone, A.
Diameter-dependent elastic properties of carbon nanotube-polymer composites: Emergence of size effects from atomistic-scale simulations Journal Article
In: COMPOSITES. PART B, ENGINEERING, vol. 131, pp. 260–281, 2017.
Abstract | BibTeX | Tags: Atomistic simulations, Finite element analysis, Interface/interphase, Polymer-matrix composites | Links:
@article{Malagu2017,
title = {Diameter-dependent elastic properties of carbon nanotube-polymer composites: Emergence of size effects from atomistic-scale simulations},
author = {M. Malagù and M. Goudarzi and A. Lyulin and E. Benvenuti and A. Simone},
doi = {10.1016/j.compositesb.2017.07.029},
year = {2017},
date = {2017-01-01},
journal = {COMPOSITES. PART B, ENGINEERING},
volume = {131},
pages = {260–281},
publisher = {Elsevier Ltd},
abstract = {We propose a computational procedure to assess size effects in nonfunctionalized single-walled carbon nanotube (CNT)-polymer composites. The procedure upscales results obtained with atomistic simulations on a composite unit cell with one CNT to an equivalent continuum composite model with a large number of CNTs. Molecular dynamics simulations demonstrate the formation of an ordered layer of polymer matrix surrounding the nanotube. This layer, known as the interphase, plays a central role in the overall mechanical response of the composite. Due to poor load transfer from the matrix to the CNT, the reinforcement effect attributed to the CNT is negligible; hence the interphase is regarded as the only reinforcement phase in the composite. Consequently, the mechanical properties of the interface and the CNT are not derived since their contribution to the elastic response of the composite is negligible. To derive the elastic properties of the interphase, we employ an intermediate continuum micromechanical model consisting of only the polymer matrix and a three-dimensional fiber representing the interphase. The Young's modulus and Poisson's ratio of the equivalent fiber, and therefore of the interphase, are identified through an optimization procedure based on the comparison between results from atomistic simulations and those obtained from an isogeometric analysis of the intermediate micromechanical model. Finally, the embedded reinforcement method is employed to determine the macroscopic elastic properties of a representative volume element of a composite with various fiber volume fractions and distributions. We then investigate the role of the CNT diameter on the elastic response of a CNT-polymer composite; our simulations predict a size effect on the composite elastic properties, clearly related to the interphase volume fraction.},
keywords = {Atomistic simulations, Finite element analysis, Interface/interphase, Polymer-matrix composites},
pubstate = {published},
tppubtype = {article}
}
We propose a computational procedure to assess size effects in nonfunctionalized single-walled carbon nanotube (CNT)-polymer composites. The procedure upscales results obtained with atomistic simulations on a composite unit cell with one CNT to an equivalent continuum composite model with a large number of CNTs. Molecular dynamics simulations demonstrate the formation of an ordered layer of polymer matrix surrounding the nanotube. This layer, known as the interphase, plays a central role in the overall mechanical response of the composite. Due to poor load transfer from the matrix to the CNT, the reinforcement effect attributed to the CNT is negligible; hence the interphase is regarded as the only reinforcement phase in the composite. Consequently, the mechanical properties of the interface and the CNT are not derived since their contribution to the elastic response of the composite is negligible. To derive the elastic properties of the interphase, we employ an intermediate continuum micromechanical model consisting of only the polymer matrix and a three-dimensional fiber representing the interphase. The Young's modulus and Poisson's ratio of the equivalent fiber, and therefore of the interphase, are identified through an optimization procedure based on the comparison between results from atomistic simulations and those obtained from an isogeometric analysis of the intermediate micromechanical model. Finally, the embedded reinforcement method is employed to determine the macroscopic elastic properties of a representative volume element of a composite with various fiber volume fractions and distributions. We then investigate the role of the CNT diameter on the elastic response of a CNT-polymer composite; our simulations predict a size effect on the composite elastic properties, clearly related to the interphase volume fraction.
2013
1.
Pedersen, R. R., Simone, A., Sluys, L. J.
Mesoscopic modeling and simulation of the dynamic tensile behavior of concrete Journal Article
In: CEMENT AND CONCRETE RESEARCH, vol. 50, pp. 74–87, 2013.
Abstract | BibTeX | Tags: Concrete, Degradation, Dynamics, Finite element analysis, Microstructure | Links:
@article{Pedersen2013,
title = {Mesoscopic modeling and simulation of the dynamic tensile behavior of concrete},
author = {R. R. Pedersen and A. Simone and L. J. Sluys},
doi = {10.1016/j.cemconres.2013.03.021},
year = {2013},
date = {2013-01-01},
journal = {CEMENT AND CONCRETE RESEARCH},
volume = {50},
pages = {74–87},
publisher = {PERGAMON-ELSEVIER SCIENCE LTD},
abstract = {We present a two-dimensional mesoscopic finite element model for simulating the rate- and moisture-dependent material behavior of concrete. The idealized mesostructure consists of aggregate grains surrounded by an interfacial transition zone embedded in the bulk material. We examine the influence of the most significant constitutive model parameters on global and local response. Different distributions and shapes of the aggregate grains are tested. Three model parameter sets, corresponding to different moisture conditions, are employed in the analysis of two specimens in which the applied loading rate is significantly different The results indicate that the loading rate has a stronger influence than the saturation level on fracture processes and global strength.},
keywords = {Concrete, Degradation, Dynamics, Finite element analysis, Microstructure},
pubstate = {published},
tppubtype = {article}
}
We present a two-dimensional mesoscopic finite element model for simulating the rate- and moisture-dependent material behavior of concrete. The idealized mesostructure consists of aggregate grains surrounded by an interfacial transition zone embedded in the bulk material. We examine the influence of the most significant constitutive model parameters on global and local response. Different distributions and shapes of the aggregate grains are tested. Three model parameter sets, corresponding to different moisture conditions, are employed in the analysis of two specimens in which the applied loading rate is significantly different The results indicate that the loading rate has a stronger influence than the saturation level on fracture processes and global strength.
