arXiv subjects

Ryan C. Hurley

Publications and source records attributed to Ryan C. Hurley.

4 recordsLinked to original sources

arXiv2026

Mechanism of Band Gap Formation in Beam Networks

Band gaps are commonly attributed to Bragg scattering or local resonance, yet it remains unclear whether these mechanisms govern band gap formation in beam networks. In this work, we explain band gap formation in beam networks in terms of a new mechanism, geometry-induced coupling between deformation modes. Specifically, band gap onset arises from axial-bending coupling at lattice nodes and scales with the axial cutoff frequency of a one-dimensional periodic beam, whereas band gap termination is primarily governed by high-frequency rotational branches associated with beam geometry. This mechanism holds for both periodic and disordered beam networks. In periodic lattices, it manifests through beam orientations at lattice nodes, whereas in disordered networks it manifests through short-beam statistics arising from variations in beam length. Together, these results establish a unified mechanism for band gap formation across both periodic and disordered beam networks, providing new insight into the physical origin of band gaps in beam-network materials.

cond-mat.mtrl-sci↗

arXiv2025

Dynamic Heterogeneity and Facilitation in Sheared Granular Materials: Insights from 3D Triaxial Testing

Strain localization in granular materials arises from complex microscale dynamics, including intermittent particle rearrangements and spatiotemporally correlated deformation. While dynamic heterogeneity (DH) and dynamic facilitation (DF) have been widely studied in two-dimensional amorphous materials, their prevalence in three-dimensional (3D) granular systems remains unclear. Here, we performed a 3D triaxial compression test with in-situ X-ray computed tomography to track particle-scale kinematics across small and large strain increments. We analyzed deviatoric strain, volumetric strain, and non-affine motion fields, computed four-point spatial dynamic correlation functions to probe DH, quantified DF through a facilitation ratio, and assessed temporal persistence of local dynamics using four-point temporal dynamic correlations. Across large strain increments, DH and DF emerge strongly in the transition regime between the initially elastic response and the critical state regime, but weaken or become statistically insignificant within the shear band at the critical state, indicating a qualitative change in microscale dynamics upon localization. In contrast, under small increments, both measures are suppressed across all regimes. These results demonstrate that correlated dynamics depend strongly on both strain increment and deformation regime. This work provides the first comprehensive investigation of DH and DF in 3D granular materials and highlights their strain-increment and regime-dependent behaviors, establishing a connection to glassy dynamics in amorphous solids.

cond-mat.soft↗

arXiv2025

The Interplay Between Forces, Particle Rearrangements, and Macroscopic Stress Fluctuations in Sheared 2D Granular Media

Recent studies have established correlations between non-affine motion and macroscopic stress fluctuations in sheared granular media. However, a comprehensive examination of the relationship between non-affine motion, macroscopic stress fluctuations, and inter-particle forces remains lacking. We investigated this interplay in simulations of 2D granular media during stick-slip events under plane shear. We found that, during most large slip events, particles with the greatest non-affine motion, as quantified by D2min, initially coalesce into one or two dominant connected clusters. These clusters coincide with the region exhibiting the greatest instantaneous reduction in inter-particle forces, indicating a significant correlation between inter-particle force fluctuations and particle rearrangements. Furthermore, the magnitude of the greatest non-affine motion within these clusters correlates strongly with the magnitude of macroscopic stress fluctuations during slip events. This correlation increased when the non-affine motion of particles in a neighborhood around the point of greatest non-affine motion was included in the analysis, suggesting that plastic events are best understood as regional rather than point-like occurrences. Our results held for various inter-particle friction coefficients. Our findings suggest that elastoplastic models should consider plastic events as regional rather than point-like and highlight the importance of studying the propagation of particle rearrangements.

cond-mat.soft↗

arXiv2020

Predicting high rate granular transition and fragment statistics at the onset of granular flow for brittle ceramics

Brittle materials under impact loading exhibit a transition from a cracked solid to a granular medium. Appropriate representation of this transition to granular mechanics and the resulting initial fragment size and shape distribution in computational models is not well understood. The current work provides a numerical model to analyze competitive crack coalescence in the transition regime and provides insight into the onset of comminution and the initial conditions for subsequent granular flow. Crack statistics obtained from initial flaws using a wing crack growth based damage model have been used to discretely model elliptical cracks in three dimensions, with and without a minimal intersection constraint. These cracks are then allowed to coalesce with nearby cracks along favourable directions and the output fragment statistics have been predicted. The evolving fragmentation offers insight into the onset of comminution as well as the final transition to granular mechanics and the resulting initial fragment statistics. A simple phenomenological model has been proposed that suggests a transition criterion resembling the one obtained from the numerical model.

cond-mat.soft↗