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What is the Nanomaterial Mechanics Explorer?
This tool enables users to explore properties of materials from the atomistic scale including dislocation motion, crack propagation, plastic deformation, melting, and martensitic transformation. The tool uses molecular dynamics simulations with pre-built examples and full control of individual simulation parameters for experienced users within advanced options. The pre-built examples are described below. All simulations use the LAMMPS molecular dynamics code  and embedded-atom method interatomic models . The tool connects to OpenKIM , a database of interatomic models, enabling simulation of over 25 elements and 20 alloys from more than 100 models.
For each simulation, an atomistic visualization of the system is output, as well as visualization of only defective atoms (those which do not match the initial crystal structure). All other outputs are chosen by the user and specific to the individual simulation, e.g. for those simulations that strain the system, a stress strain curve can be output. All curve and point outputs can be used with the uncertainty quantification infrastructure within Rappture to run a series of simulations automatically to study the effect of input uncertainty on the outputs of interest.
Nanowire Tensile Test
This module strains nanowires under uniaxial tension to examine resolved shear stress, slip plane activation, necking, and other topics within plastic deformation. Changing wire orientation, strain rate, and temperature alter the results most significantly.
Users can choose between copper in various base orientations ( , , ,  ) or nickel in the , all at 300K.
Within this module the user can visualize how dislocations either glide or nucleate in the crystal based on the applied stress direction relative to the Burgers vector, slip plane, and dislocation line. If there is no resolved shear stress, dislocations will nucleate rather than glide; this option can be enabled in the advanced options.
Current options include edge and screw type dislocations in copper and iron, all at 300K. An additional case shows screw dislocations in copper annihilating. Note that building the dislocation structure is not currently available in the advanced options.
This module simulates a crack under uniaxial tension where the system eventually fails under ductile or brittle fracture depending primarily on temperature and strain rate.
Available pre-built systems include nickel and tantalum, each at 300K and 600K.
In this module melting is studied at the atomistic level. A solid crystal is heated through its ambient pressure melting temperature until it is fully liquid with commensurate changes in energy and structure,
The two pre-built simulations investigate melting in nickel bulk or nanoparticle systems.
A more complex phase transition is also available. In these default simulations the system is cooled through the martensite start and finish temperatures and the process is reversed to demonstrate shape memory behavior. One alloy, 63% Ni, 37% Al exhibits a martensitic transformation while a second, 50% Ni 50% Al does not transform.
Options pre-built for the module are the 63% Ni 37% Al (martensitic) and 50% Ni, 50% Al (non-martensitic) systems to contrast behavior.
In addition, two examples from Strachan Group research contrast a Ni(63)Al(37) martensitic nanowire and a metamaterial 70% Ni(63)Al(37) / 30% Ni(50)Al(50) nanowire. These cases are strained at 300K to demonstrate the ultra-low stiffness of the composite nanowire.
LAMMPS molecular dynamics simulation code , an open source project distributed by Sandia National Laboratory: http://lammps.sandia.gov/doc/Manual.html
OpenKIM interatomic model repository , a National Science Foundation supported project: https://openkim.org/
This tool is developed by the Strachan Research Group:
The tool was initially developed during the summer of 2015 and continued with work by the following:
- Christopher Chow (NCN-SURF program): Summer 2016
- Michael Sakano (NCN-SURF program; Purdue MSE graduate student): Summer 2015; Summer 2016 - present
- Shuhui Tang (NCN-SURF program): Summer 2015
- Alexis Belessiotis (Imperial College London visiting student): Summer 2015
- Sam Reeve (Purdue MSE graduate student): Summer 2015 - present
- Mitch Wood (Purdue MSE graduate student): Summer 2015 - Summer 2016
- Kiettipong Banlusan (Purdue MSE graduate student): Summer 2015 - Summer 2017
Significant design and direction by Professor Alejandro Strachan and additional support from Ben Haley throughout.
- Network for Computational Nanotechnology (NCN), supported by the US National Science Foundation
- US Department of Energy Basic Energy Sciences (DoE-BES) program under Program No. DE-FG02-07ER46399.
 S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995).
 M. S. Daw, and M. I. Baskes, Embedded-atom method: Derivation and application to impurities, surfaces, and other defects in metals, Phys. Rev. B, 29, 6443 (1984).
 E. B. Tadmor, R. S. Elliott, J. P. Sethna, R. E. Miller, and C. A. Becker. Knowledgebase of Interatomic Models (KIM), https://openkim.org, 2011.
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