Images & Movies

ACS Macro Letters Cover: Identifying molecular features that strengthen materials

The faster you deform a polymer, the stiffer it becomes—until the stiffness plateaus at very high rates. We used a theory and simulations to identify some specific molecular features that lead to stiffness or softness. For more details, see "Identifying nonaffine softening modes in glassy polymer networks: A pathway to chemical design." Elder, et al. ACS Macro Lett. 2019, 8, 1160-1165. Cover image released in ACS Macro Letters, Vol. 8, Iss 9. Rendered using Blender.

Soft Matter Cover: Nanovoid Nucleation

Representation of nanovoid nucleation in a rugged energy landscape, with timescales accelerated using specialized simulation techniques. For more details, see "Mechanics and nanovoid nucleation dynamics: Effects of polar functionality in glassy polymer networks", Elder et al., Soft Matter, 2018, 14, 8895-8911. Cover image released in Soft Matter, 28 November 2018, Issue 44, Page 8863 to 9072. Rendered using Blender.

Jacks rolling down a ramp

This video demonstrates the utility of simulations for studying granular materials (like gravel or sugar), which are relevant in a variety of industrial contexts. The jacks are first dropped onto a flat surface which is then tilted to 30 degrees, causing them to roll downward (to the right). The edges of the periodic simulation box are shown in black, and multiple periodic images are shown. The jacks are modeled as rigid bodies. I did the simulations with LAMMPS and visualization with OVITO.

Brazil nut effect

An example of granular convection, also called the Brazil nut effect, which causes a large particle to float upwards through an agitated sea of smaller particles. The particles are first dropped into a cylindrical container and then agitated by a vibrating plate. I used molecular dynamics simulations to model granular particles using LAMMPS and rendered the video using VMD. (I got this idea from another video.)

Nanovoid in cross-linked polymer

Images I created for a paper on nanoscale voids that form in cross-linked polymers during mechanical deformation. A large nanovoid is highlighted in the center of the system. The first image shows a zoomed-out view of the system. The boundaries of the simulation box are shown in blue. The entire box is filled with polymer, but atoms in the front half of the system are hidden to make the void visible. The second image shows a close-up of the void. These images were created using VMD and the Tachyon ray-tracer. The red lighting in the void was created using ideas from John Stone's glowlights script.

Nanoindentation of graphene / MoS₂ layered structures

Indentation of a three layered structure of MoS₂, graphene, and MoS₂ with an indenter (transparent sphere) from our paper in Applied Physics Letters. The structure is suspended at the edge (blue). The upper layer of MoS₂ (mostly yellow) has ruptured under the stress, while the central graphene layer (gray) and the lower layer of MoS₂ are still intact. Rendered with VMD.