| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | July 25, 2019 |
| Latest Amendment Date: | July 25, 2019 |
| Award Number: | 1937983 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Wendy C. Crone
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | July 15, 2019 |
| End Date: | February 28, 2022 (Estimated) |
| Total Intended Award Amount: | $170,604.00 |
| Total Awarded Amount to Date: | $170,604.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1400 TOWNSEND DR HOUGHTON MI US 49931-1200 (906)487-1885 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1400 Townsend Dr. Houghton MI US 49931-1295 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Mechanics of Materials and Str |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Two-dimensional materials are made of chemical elements or compounds of elements while maintaining a single atomic layer crystalline structure. Two-dimensional materials, especially Transition Metal Dichalcogenides (TMDs), have shown tremendous promise to be transformed into advanced material systems and devices, e.g., field-effect transistors, solar cells, photodetectors, fuel cells, sensors, and transparent flexible displays. To achieve broader use of TMDs across cutting-edge applications, complex deformations for large-area TMDs must be better understood. Large-area TMDs can be simulated and analyzed through predictive modeling, a capability that is currently lacking. This EArly-concept Grant for Exploratory Research (EAGER) award supports fundamental research that overcomes current challenges in large-scale atomistic modeling to obtain an efficient but reliable continuum model for single-layer TMDs containing billions of atoms. The model will be translational and will contribute towards the development of a wide range of applications in the nanotechnology, electronics, and alternative energy industries. The award will further support development of an advanced graduate-level course on multiscale modeling and organization of symposia in two international conferences on mechanics of two-dimensional materials.
Experimental samples of TMDs contain billions of atoms and hence are inaccessible to the state-of-the-art molecular dynamics simulations. Moreover, existing crystal elastic models for surfaces cannot be applied to multi-atom thick 2D TMDs due to the presence of interatomic bonds across the atomic surfaces. The crystal elastic model aims to solve this problem by projecting all interatomic bonds onto the mid-surface to track their deformations. The actual deformed bonds will, therefore, be computed using the deformations of the mid-surface. Additionally, a technique will be derived to incorporate the effects of curvature and stretching of TMDs on their interactions with substrates. The model will be exercised to generate insights into the mechanical instabilities and the role of substrate interactions on them. The coarse-grained model will overcome the computational bottleneck of molecular dynamics models to simulate TMDs samples comprising billions of atoms.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
State-of-the-art finite deformation crystal-elasticity models are available only for single-atom-thick crystalline membranes, e.g. graphene. These models cannot be applied to multi-atom-thick 2D materials such as monolayer Transition Metal Dichalcogenides (TMDs), since they have covalent bonds located out of the middle surface of the membrane. The present model generalizes the crystal-elasticity-based membrane theory of purely 2D membranes, such as graphene, to the multi-atom-thick TMD crystalline membranes. The proposed atomistic-based continuum model accurately matches the material moduli, complex post-buckling deformations, and the equilibrium energies predicted by the purely atomistic simulations. The proposed atomistic-based continuum model also accurately reproduces the experimental results for large-area TMD samples containing tens of millions of atoms.
One Ph.D. student was trained on: (i) 2D materials, (ii) crystal-elasticity-based multiscale modeling, (iii) membrane theory, (iv) smooth finite element framework using B-splines, (v) atomistic simulations, and (vi) High Performance Computing. Another Ph.D. student was trained on efficient surrogate model development for crystal-elasticity-based constitutive relation. Several MS students were trained on mechanics of 2D materials and numerical methods.
Three manuscripts are submitted for publications in top tier journals, two of them are published and one is under review. The e-print of the paper under review is made available through an open-access archive. One peer reviewed conference paper is published. The results are presented in several conferences.
Transition metal dichalcogenides (TMDs) are emerging two-dimensional (2D) materials that exhibit exceptional electrical, optical, and chemical properties, therefore, the present model will have a great impact on their mechanics-based insights, design, and analysis. The electronic band-gap in TMDs can be reversibly tuned via mechanical strain. Wrinkles or folds in TMDs also can reversibly alter their electronic, opto-electronic, and surface properties, which is promising for various high-impact applications. Complex mechanical deformations of large TMDs, such as wrinkles and folds are important as it can allow us to alter their properties in a very controlled manner. The present model enables accurate prediction of such complex mechanical deformations and hence would have a great impact in the simulation and design of devices made of TMDs.
Last Modified: 05/02/2022
Modified by: Susanta Ghosh
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