An elastoplastic framework for granular materials becoming cohesive through mechanical densification. Part I - small strain formulation

TL;DR

This paper develops a small strain elastoplastic model that describes how granular materials become cohesive through mechanical densification, integrating nonlinear elastic and plastic behaviors with experimental calibration.

Contribution

It introduces a novel elastoplastic coupling approach to model the transition from loose granular to dense cohesive states, calibrated with experimental data.

Findings

Successfully describes the densification process

Captures the evolution of cohesion and elastic properties

Provides a foundation for large strain generalization

Abstract

Mechanical densification of granular bodies is a process in which a loose material becomes increasingly cohesive as the applied pressure increases. A constitutive description of this process faces the formidable problem that granular and dense materials have completely different mechanical behaviours (nonlinear elastic properties, yield limit, plastic flow and hardening laws), which must both be, in a sense, included in the formulation. A treatment of this problem is provided here, so that a new phenomenological, elastoplastic constitutive model is formulated, calibrated by experimental data, implemented and tested, that is capable of describing the transition between granular and fully dense states of a given material. The formulation involves a novel use of elastoplastic coupling to describe the dependence of cohesion and elastic properties on the plastic strain. The treatment falls within small strain theory, which is thought to be appropriate in several situations; however, a generalization of the model to large strain is provided in Part II of this paper.