Crossover scaling of structural and mechanical properties in 3D assemblies of non-spherical, frictional particles

The stability of particle assemblies is strongly affected by particle shape, yet definitive laws describing key properties, such as the mean contact number and apparent friction coefficient, remain elusive. Using X-ray computed tomography and discrete element simulations, we study 70 assemblies of 3D frictional particles. Once properly rescaled, our data collapse onto master curves, revealing linear relationships linking particle shape to these properties for short-axis particles below certain crossover points. These data suggest that the scaling behavior for the mean contact number can be maintained at lower sphericity than the apparent friction coefficient, indicating different sensitivity of the system’s structural versus mechanical properties to particle shape. Through analyzing elongated particles beyond the crossover points, we find that while particle elongation increases the contact number, it has limited effects on improving mechanical stability. This insight, along with the law, paves the route towards optimizing granular packing via manipulating particle shape. The stability of granular assemblies depends on particle shape, but clear laws governing key properties like contact number and friction coefficient remain elusive. Using X-ray tomography and simulations, the authors uncover linear scaling laws linking shape to these properties, showing that the scaling of contact number persists at a lower sphericity than that for the apparent friction coefficient, and that elongation increases contact numbers but does not significantly enhance stability.