Mechanical and Structural Contributions to Anisotropy in Granular Materials

Fuente: arXiv
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Hauptverfasser: Pouragha, Mehdi, Medicus, Gertraud, Premnath, Selvarajah, Sivathayalan, Siva
Format: Preprint
Veröffentlicht: 2026
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author Pouragha, Mehdi
Medicus, Gertraud
Premnath, Selvarajah
Sivathayalan, Siva
author_facet Pouragha, Mehdi
Medicus, Gertraud
Premnath, Selvarajah
Sivathayalan, Siva
contents Anisotropy in granular materials arises from both the internal fabric and the directionality of the stress state, yet separating these effects experimentally remains challenging. This study develops a first-order linearisation of the incremental stress-strain response that isolates mechanical anisotropy from structural anisotropy using two independent orientation measures. The formulation enables both contributions to be quantified directly from macroscopic laboratory data. The method is applied to hollow-cylinder tests with systematically varied loading directions. Results show that both anisotropy components intensify as the stress state becomes more deviatoric; mechanical anisotropy is consistently stronger; and its relative dominance decreases with increasing deviatoric stress. Comparison with an isotropic hypoplastic model confirms that mechanically induced directional effects are captured even without fabric anisotropy. The framework offers a practical and physically transparent means for quantifying and comparing anisotropy mechanisms in granular materials.
format Preprint
id arxiv_https___arxiv_org_abs_2602_19902
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Mechanical and Structural Contributions to Anisotropy in Granular Materials
Pouragha, Mehdi
Medicus, Gertraud
Premnath, Selvarajah
Sivathayalan, Siva
Soft Condensed Matter
Materials Science
Anisotropy in granular materials arises from both the internal fabric and the directionality of the stress state, yet separating these effects experimentally remains challenging. This study develops a first-order linearisation of the incremental stress-strain response that isolates mechanical anisotropy from structural anisotropy using two independent orientation measures. The formulation enables both contributions to be quantified directly from macroscopic laboratory data. The method is applied to hollow-cylinder tests with systematically varied loading directions. Results show that both anisotropy components intensify as the stress state becomes more deviatoric; mechanical anisotropy is consistently stronger; and its relative dominance decreases with increasing deviatoric stress. Comparison with an isotropic hypoplastic model confirms that mechanically induced directional effects are captured even without fabric anisotropy. The framework offers a practical and physically transparent means for quantifying and comparing anisotropy mechanisms in granular materials.
title Mechanical and Structural Contributions to Anisotropy in Granular Materials
topic Soft Condensed Matter
Materials Science
url https://arxiv.org/abs/2602.19902