Bonded particle models

This is work by Joel Clemmer (Sandia) using the bonded particle model (BPM) package they added to LAMMPS where particles are connected by bonds to model solid mechanics. Bonds contain history, remembering their reference state and/or strain history, and can break to model fracture.

The first video is the bpm/pour example in the LAMMPS distribution where elongated elastic objects constructed out of bonded particles are dropped into a cylindrical cup.

In the second video, a granular system is compacted to a nearly fully dense state. Spherical grains are constructed out of a collection of bonded particles that produce an isotropic linear elastic response. Color represents different grains.

The third video is a two-dimensional example of fragmentation where a solid block of material is continually sheared until it breaks into millions of power-law distributed fragments. Kraynik-Reinelt boundary conditions, the 2D analog of the UEF package, are used to reach large strains. Color indicates the number of broken bonds.

Lastly in the fourth video, a polymer-bonded granular composite is loaded to failure. Spherical nearly-rigid grains are inserted into a matrix of plastic binder. Three types of bonds are used, a very stiff elastic bond between grain-grain particles, a softer elastic interfacial bond between grain-polymer particles, and an elastic-perfectly-plastic bond between polymer-polymer particles. Color indicates the number of broken bonds.

All visualizations were performed with OVITO.