Localisation and fracture propagation in materials with rotating grains and transitional negative stiffness

Yuan Xu

Research output: ThesisDoctoral Thesis

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Abstract

We investigate failure of particulate materials with constituents having rotational degrees of freedom and producing moment stresses. We show that micro tensile stresses in the inter-particle links bent due to particle relative rotations are the dominant stresses mode. Analysis and discrete element modelling show that rolling of compound particles (grouping of two spherical particles) produces apparent negative stiffness. We also identify a new, momentarily emerging, negative stiffness during the formation of crack or bond breakage. This, transitional negative stiffness, increases the Poisson's ratio to the critical values corresponding to elastic instability, which forms a mechanism of strain localisation.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • The University of Western Australia
Thesis sponsors
Award date4 Jun 2019
DOIs
Publication statusUnpublished - 2019

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Stiffness
Degrees of freedom (mechanics)
Poisson ratio
Tensile stress
Cracks

Cite this

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title = "Localisation and fracture propagation in materials with rotating grains and transitional negative stiffness",
abstract = "We investigate failure of particulate materials with constituents having rotational degrees of freedom and producing moment stresses. We show that micro tensile stresses in the inter-particle links bent due to particle relative rotations are the dominant stresses mode. Analysis and discrete element modelling show that rolling of compound particles (grouping of two spherical particles) produces apparent negative stiffness. We also identify a new, momentarily emerging, negative stiffness during the formation of crack or bond breakage. This, transitional negative stiffness, increases the Poisson's ratio to the critical values corresponding to elastic instability, which forms a mechanism of strain localisation.",
keywords = "Particulate material, DEM, Moment stresses, Grain relative rotations, Localisation, Fracture propagation, Negative stiffness",
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school = "The University of Western Australia",

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AB - We investigate failure of particulate materials with constituents having rotational degrees of freedom and producing moment stresses. We show that micro tensile stresses in the inter-particle links bent due to particle relative rotations are the dominant stresses mode. Analysis and discrete element modelling show that rolling of compound particles (grouping of two spherical particles) produces apparent negative stiffness. We also identify a new, momentarily emerging, negative stiffness during the formation of crack or bond breakage. This, transitional negative stiffness, increases the Poisson's ratio to the critical values corresponding to elastic instability, which forms a mechanism of strain localisation.

KW - Particulate material

KW - DEM

KW - Moment stresses

KW - Grain relative rotations

KW - Localisation

KW - Fracture propagation

KW - Negative stiffness

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DO - 10.26182/5d15c0d3e92ac

M3 - Doctoral Thesis

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