Dynamic fracture behavior of single and contacting Poly(methyl methacrylate) particles

The fracture initiation in single, two, and multiple PMMA particles under dynamic compression. For all contact conditions, the cracking initiated near the center of the particles and fractured the particles in two approximately hemispherical fragments with conical fragments at the contact (Scale bars=100μm). [Display omitted] •Synchrotron X-ray imaging was used to study the fracture of PMMA particles.•One, two, and multiple contacting particles in a hexagonal packing were studied.•Cracking initiated near the center of the particle for all contact conditions.•The particles fractured in two hemispherical fragments.•Resulting fragments fractured further to display the orange-slice fracture pattern. Fracture behaviors of single, two, and multiple contacting spherical Poly(methyl methacrylate) (PMMA) particles were recorded using high speed synchrotron X-ray phase contrast imaging. A miniaturized Kolsky bar setup was used to apply dynamic compressive loading on the PMMA particles. In both single and two particle experiments, cracking initiated near the center of the particles and propagated towards the contacts. The crack bifurcated near the contact points for single particle experiments, thus forming conical fragments. The crack bifurcation and subsequent conical fragment formation was observed only at the particle-particle contact for two particle experiments. The particles were observed to fracture in hemispherical fragments normal to the contact plane in the multi-particle experiments. The observed failure mechanisms strongly suggest that the maximum tensile stress near the center of the particle is the critical parameter governing fracture of the particles. Furthermore, the compressive stress under the contact areas led to the bifurcation and subsequent conical fragment formation.