Abstract
Novel 2D materials, e.g., graphene oxide (GO), are attractive building blocks in the design of advanced materials due to their reactive chemistry, which can enhance interfacial interactions while providing good in-plane mechanical properties. Recent studies have hypothesized that the randomly distributed two-phase microstructure of GO, which arises due to its oxidized chemistry, leads to differences in nano- vs meso‑scale mechanical responses. However, this effect has not been carefully studied using molecular dynamics due to computational limitations. Herein, a continuum mechanics model, formulated based on density functional based tight binding (DFTB) constitutive results for GO nano-flakes, is establish for capturing the effect of oxidation patterns on the material mechanical properties. GO is idealized as a continuum heterogeneous two-phase material, where the mechanical response of each phase, graphitic and oxidized, is informed from DFTB simulations. A finite element implementation of the model is validated via MD simulations and then used to investigate the existence of GO representative volume elements (RVE). We find that for the studied GO, an RVE behavior arises for monolayer sizes in excess to 40 nm. Moreover, we reveal that the response of monolayers with two main different functional chemistries, epoxide-rich and hydroxyl‑rich, present distinct differences in mechanical behavior. In addition, we explored the role of defect density in GO, and validate the applicability of the model to larger length scales by predicting membrane deflection behavior, in close agreement with previous experimental and theoretical observations. As such the work presents a reduced order modeling framework applicable in the study of mechanical properties and deformation mechanisms in 2D multiphase materials.
Original language | English (US) |
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Pages (from-to) | 66-88 |
Number of pages | 23 |
Journal | Journal of the Mechanics and Physics of Solids |
Volume | 112 |
DOIs | |
State | Published - Mar 2018 |
Funding
The authors acknowledge the support of NSF through DMREF Award No. CMMI-1235480 and the ARO through MURI Award No. W911NF-08-1-0541. Transmission electron microscopy was performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, and supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. DFTB calculations were carried out on the TACC Stampede high performance computing facility, at the University of Texas at Austin, through the support of NSF XSEDE Award Nos. TG-MSS140028 and TG-MSS150003. I.B. acknowledges support from a Fulbright Visiting Research Scholarship. H.T.N. acknowledges support from the Vietnam Education Foundation. R.A.S-C. acknowledges support from NSF through the Graduate Research Fellowships Program (GRFP), partial support from the Northwestern University Ryan Fellowship & International Institute for Nanotechnology and partial support from Northwestern University through a Royal Cabell Terminal Year Fellowship. The authors thank Antonio Pedivellano for helpful discussions. The authors acknowledge the support of NSF through DMREF Award No. CMMI-1235480 and the ARO through MURI Award No. W911NF-08-1-0541 . Transmission electron microscopy was performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, and supported by the U.S. Department of Energy , Office of Science, under Contract No. DE-AC02-06CH11357 . DFTB calculations were carried out on the TACC Stampede high performance computing facility, at the University of Texas at Austin, through the support of NSF XSEDE Award Nos. TG-MSS140028 and TG-MSS150003 . I.B. acknowledges support from a Fulbright Visiting Research Scholarship. H.T.N. acknowledges support from the Vietnam Education Foundation . R.A.S-C. acknowledges support from NSF through the Graduate Research Fellowships Program (GRFP), partial support from the Northwestern University Ryan Fellowship & International Institute for Nanotechnology and partial support from Northwestern University through a Royal Cabell Terminal Year Fellowship. The authors thank Antonio Pedivellano for helpful discussions.
Keywords
- Continuum damage model
- Finite element analysis
- Graphene oxide
- Membrane deflection
- Model development and validation
- Representative volume elements
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering