Absence of `fragility' and mechanical response of jammed granular materials

摘要

We perform molecular dynamic (MD) simulations of frictional non-thermalparticles driven by an externally applied shear stress. After the system jamsfollowing a transient flow, we probe its mechanical response in order toclarify whether the resulting solid is 'fragile'. We find the system to respondelastically and isotropically to small perturbations of the shear stress,suggesting absence of fragility. These results are interpreted in terms of theenergy landscape of dissipative systems. For the same values of the controlparameters, we check the behaviour of the system during a stress cycle.Increasing the maximum stress value, a crossover from a visco-elastic to aplastic regime is observed.