I study the average deformation rate of an amorphous material submitted to an external uniform shear strain rate, in the geometry known as the split-bottom configuration. The material is described using a stochastic model of plasticity at a mesoscopic scale. A shear band is observed to start at the split point at the bottom, and widen progressively towards the surface. In a two-dimensional geometry the average statistical properties of the shear band look similar to those of the directed polymer model. In particular, the surface width of the shear band is found to scale with the system height H as H;{alpha} with alpha=0.68+/-0.02 . In more realistic three-dimensional simulations the exponent changes to alpha=0.60+/-0.02 and the bulk profile of the width of the shear band is closer to a quarter of a circle, as it was observed to be the case in recent simulations of granular materials.
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http://dx.doi.org/10.1103/PhysRevE.78.026105 | DOI Listing |
Materials (Basel)
December 2024
Suzhou XDM 3D Printing Technology Co., Ltd., Suzhou 215000, China.
The stress distribution within the struts of lattice metamaterials is non-uniform under compressive loads, with stress concentrations typically occurring at the node regions. Inspired by bamboo, this study proposes a type of body-centered cubic (BCC) lattice metamaterial with tapered prism struts (BCCT). The compressive behavior, deformation modes, mechanical properties, and failure mechanisms of BCCT lattice metamaterials are systematically analyzed using finite element methods and validated through compression tests.
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January 2025
Veterinary Referral Hospital, Dandenong, Victoria, Australia.
A 4-year-old Siberian Husky was referred for bilateral hock trauma after being involved in a road traffic accident. The dog sustained a grade 3 shearing injury to the medial right hock with tibiotarsal subluxation, which was managed with a transarticular frame. The left hock sustained a rare open longitudinal split fracture of the lateral malleolus, resulting in lateral tarsocrural instability.
View Article and Find Full Text PDFThe potential application of materials referred to as perovskite hydrides in hydrogen storage - a crucial element of renewable energy systems - has sparked a great deal of interest. We use density functional theory (DFT) to investigate the structural, formation energy, hydrogen storage, electronics, thermoelectric and elastic properties of NaXH (X = Be, Mg, Ca, and Sr) hydrides. The band gap is calculated using WC-GGA and WC-GGA+mBJ potentials.
View Article and Find Full Text PDFScience
December 2024
Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore.
The structural periodicity in photonic crystals guarantees the crystal's effective energy band structure, which is the fundamental cornerstone of topological and moiré physics. However, the shear modulus in most fluids is close to zero, which makes it challenging for fluids to maintain spatial periodicity akin to photonic crystals. We realized periodic vortices in hydrodynamic metamaterials and created a bilayer moiré superlattice by stacking and twisting two such vortex fluids.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
Department of Mechanical Engineering, Howard University, Washington, DC 20059, USA.
This study examined the effects of heat treatment on the microstructure and dynamic deformation characteristics of AA2519 aluminum alloy in T4, T6, and T8 tempers under high strain rates of 1000-4000 s. A Split Hopkinson pressure bar (SHPB) was utilized to characterize the mechanical response, and microstructural analysis was performed to examine the material's microstructure. The findings indicated varied deformation across all three temper conditions.
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