(77g) Breakage of Fractal Agglomerates

Agglomerates are formed by small primary particles. Breakage of agglomerates has received considerable research attention due to its association with various industrial processes such as the production of pharmaceutical tablets and handling, transportation, or compaction of powders. Discrete element method (DEM) simulations have been widely used to investigate the breakage of agglomerates with regular shapes in previous research. In this study, breakage behavior of fractal agglomerates as a function of impact velocity and surface energy was investigated using DEM simulations. Agglomerates with fractal dimensions (D_f) ranging from about 2.0 to 2.8 were produced in this research by letting primary particles with random initial velocities agglomerate under a centripetal force. The simulation results show that the damage ratio (D_m), defined as the ratio of broken interparticle contacts to the initial total contacts, decreases with increasing fractal dimension in the range between 2.0 to 2.6, which can be explained by the increase of mechanical strength with increasing fractal dimension. Previously published Weber number (W_e) scale of damage ratio has been modified by incorporating the fractal dimension: D_m=B(W_e /D_f²)^α, where B and α depend exponentially and linearly on Weber number, respectively. Visualization of impact process illustrates the feature of ductile fracture of fractal agglomerates irrespective of fractal dimensions.