(587b) Investigating High Velocity Microparticle Impacts Via Discrete Element Method Simulations

Understanding the fundamentals of particle behavior during and after impact with a substrate is essential for optimizing a variety of particle processes including cold spray and laser powder bed fusion. In experiments, it is often challenging to study such particle-plate interactions due to the short timescales and small length scales involved. In this study, high velocity microparticle impacts are investigated using Discrete Element Method (DEM) since this simulation technique offers the ability to probe the details of the particle impact, rebound and/or fragmentation at the micro-scale in a well-structured fashion. The impacting particles are described as spherical agglomerates consisting of smaller constituent particles held together via elastic bond forces which can bend, twist, stretch and break. In this work, the effects of particle agglomerate porosity, agglomerate size, constituent particle size, impact angle, as well as particle and plate materials, are examined. With increasing size, agglomerate particles trend towards bonding with the substrate at lower impact velocities, as observed in experiments. Decreasing impact angle decreases breakage and the coefficient of restitution varies with impact velocity in a power law behavior as also observed experimentally. With decreased porosity (closest packing) of the particle agglomerate, the predicted coefficient of restitution value matches the measured value.

This work was supported by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.