The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine's unique porous structure, based on micro-computed tomography (microCT) and incorpo...

It has been contemplated for a long time that dense granular materials flow in stick-slip manner, and large fluctuations the stresses are associated with it. However, particle scale mechanics this type of macroscopic motion not understood so far. We have analyzed evolution contact networks from dynamics simulations found rate change elastic energy packing can distinguish stick regimes slip even...

Nonlinear plastic modes (NPMs) are collective displacements that are indicative of imminent plastic instabilities in elastic solids. In this work we formulate the atomistic theory that describes the reversible evolution of NPMs and their associated stiffnesses under external deformations. The deformation dynamics of NPMs is compared to those of the analogous observables derived from atomistic l...

Classical solution methods in fast Fourier transform-based computational micromechanics operate on, either, compatible strain fields or equilibrated stress fields. By contrast, polarization schemes are primal-dual whose iterates neither nor equilibrated. Recently, it was demonstrated that may outperform the classical methods. Unfortunately, their power critically depends on a judicious choice o...