From force chains to nonclassical nonlinear dynamics in cemented granular materials.

T J Ulrich,Esteban Rougier,Harvey E Goodman,Katelyn A Huffman,Marcel C Remillieux,Zhou Lei,Peter Connolly

doi:10.1103/physreve.105.l022901

T J Ulrich, Esteban Rougier + Show 5 more

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https://doi.org/10.1103/physreve.105.l022901

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Abstract

In this letter, we present evidence for a mechanism responsible for the nonclassical nonlinear dynamics observed in many cemented granular materials that are generally classified as mesoscopic nonlinear elastic materials. We demonstrate numerically that force chains are created within the complex grain-pore network of these materials when subjected to dynamic loading. The interface properties between grains along with the sharp and localized increase of the stress occurring at the grain-grain contacts leads to a reversible decrease of the elastic properties at macroscopic scale and peculiar effects on the propagation of elastic waves when grain boundary properties are appropriately considered. These effects are observed for relatively small amplitudes of the elastic waves, i.e., within tens of microstrain, and relatively large wavelengths, i.e., orders of magnitude larger than the material constituents. The mechanics are investigated numerically using the hybrid finite-discrete-element method and match those observed experimentally using nonlinear resonant ultrasound spectroscopy.

Highlights

We present evidence for a mechanism responsible for the nonclassical nonlinear dynamics observed in many cemented granular materials that are generally classified as mesoscopic nonlinear elastic materials
We demonstrate numerically that force chains are created within the complex grain-pore network of these materials when subjected to dynamic loading
The interface properties between grains along with the sharp and localized increase of the stress occurring at the grain-grain contacts leads to a reversible decrease of the elastic properties at macroscopic scale and peculiar effects on the propagation of elastic waves when grain boundary properties are appropriately considered

Summary

Introduction

Sandstone) using nonlinear resonant ultrasound spectroscopy (NRUS) with numerical simulations of the same material and dynamic loading using a combined finite-discrete element method (FDEM) in an effort to gain micro- and mesoscopic understanding of possible mechanisms for the observed hysteretic nonlinear elastic behavior. The details of the focused physical system, such as the microscale structure of the cemented granular materials, the mechanical response of the grains, and laws governing interparticle interactions, can be explicitly represented and modeled via FDEM, the number of assumptions is minimized.

Results

Conclusion