Data from: Micromechanics of compressive and tensile forces in partially-bonded granular materials

Bulk material properties such as strength and stiffness are highly
sensitive to changes in the degree of interparticle cohesion or the
introduction of elongated particles, effects that are both associated with
an increase in the average number of constraints per particle. By
performing an ensemble of isotropic compression experiments, all starting
from the same initial particle configuration but with varying fraction of
bonded particles, we use photoelastic force measurements to identify the
causes of this phenomenon at the particle-scale and meso-scale. By
introducing a variable percentage of bonded dimers, we observe the
expected decrease in the critical packing fraction at which jamming
occurs. Above jamming, the local pressure increases predominantly for the
bonded particles, measured relative to the unbonded case. The use of
bonded dimers allows us to directly measure the relative contributions of
tensile and compressive forces at the bond, which we observe occur with
approximately equal probability. Histograms of the magnitude of the
interparticle forces become broader for systems with more bonded
particles. We measure both pressure and coordination number as a function
of distance from a bonded dimer, both of which are locally enhanced for
nearest neighbors, indicating that dimers appear to act as areas of
concentrated force and connectivity that improve rigidity. These datasets
contain information about the particle location, neighbors, and the
particle-level vector contact forces.