Discrete element modelling of material non-coaxiality in simple shear flows
We investigate the quasi-static simple shear flow of a two-dimensional assembly of cohesionless particles using discrete element method (DEM) simulations. We focus on the unsteady flow regime where the solid would experience significant evolution of stresses, mobilised shear strength and dilation. W...
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| Format: | Article |
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Wiley
2014
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| Online Access: | https://eprints.nottingham.ac.uk/2403/ |
| _version_ | 1848790776434130944 |
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| author | Ai, Jun Langston, Paul A. Yu, Hai-Sui |
| author_facet | Ai, Jun Langston, Paul A. Yu, Hai-Sui |
| author_sort | Ai, Jun |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | We investigate the quasi-static simple shear flow of a two-dimensional assembly of cohesionless particles using discrete element method (DEM) simulations. We focus on the unsteady flow regime where the solid would experience significant evolution of stresses, mobilised shear strength and dilation. We construct the DEM model using a discretised-wall confined granular cell where the apparent boundary is allowed to dilate or contract synchronously with the confined solid. A rather uniform simple shear field is achieved across the whole assembly, which benefits rheological studies in generalising constitutive laws for continuum methods. We examine two aspects of the simple shear behaviour: macroscopic stress and strain rate evolution, particularly the non-coaxiality between the principal directions of the two; and micromechanics such as evolution of fabric. For an initially anisotropic specimen sheared under constant normal pressure, the direction of principal stress rotates towards that of the principal strain rate, gradually reducing the degree of non-coaxiality from about 45° to fluctuating around 0°. The rate in approaching coaxiality is slower in samples with larger initial porosity, stress ratio and mean stress. Generally, a faster rate in approaching coaxiality in simple shear is observed in a more dilatant sample, which often shows a larger degree of mobilised fabric anisotropy, suggesting the possible important role of instantaneous internal friction angle. The evolution of principal fabric direction resembles that of the principal stress direction. |
| first_indexed | 2025-11-14T18:17:59Z |
| format | Article |
| id | nottingham-2403 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T18:17:59Z |
| publishDate | 2014 |
| publisher | Wiley |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-24032020-05-04T16:46:22Z https://eprints.nottingham.ac.uk/2403/ Discrete element modelling of material non-coaxiality in simple shear flows Ai, Jun Langston, Paul A. Yu, Hai-Sui We investigate the quasi-static simple shear flow of a two-dimensional assembly of cohesionless particles using discrete element method (DEM) simulations. We focus on the unsteady flow regime where the solid would experience significant evolution of stresses, mobilised shear strength and dilation. We construct the DEM model using a discretised-wall confined granular cell where the apparent boundary is allowed to dilate or contract synchronously with the confined solid. A rather uniform simple shear field is achieved across the whole assembly, which benefits rheological studies in generalising constitutive laws for continuum methods. We examine two aspects of the simple shear behaviour: macroscopic stress and strain rate evolution, particularly the non-coaxiality between the principal directions of the two; and micromechanics such as evolution of fabric. For an initially anisotropic specimen sheared under constant normal pressure, the direction of principal stress rotates towards that of the principal strain rate, gradually reducing the degree of non-coaxiality from about 45° to fluctuating around 0°. The rate in approaching coaxiality is slower in samples with larger initial porosity, stress ratio and mean stress. Generally, a faster rate in approaching coaxiality in simple shear is observed in a more dilatant sample, which often shows a larger degree of mobilised fabric anisotropy, suggesting the possible important role of instantaneous internal friction angle. The evolution of principal fabric direction resembles that of the principal stress direction. Wiley 2014-04-25 Article PeerReviewed Ai, Jun, Langston, Paul A. and Yu, Hai-Sui (2014) Discrete element modelling of material non-coaxiality in simple shear flows. International Journal for Numerical and Analytical Methods in Geomechanics, 38 (6). pp. 615-635. ISSN 0363-9061 Simple shear Non-coaxiality Discrete element modelling http://onlinelibrary.wiley.com/doi/10.1002/nag.2230/abstract doi:10.1002/nag.2230 doi:10.1002/nag.2230 |
| spellingShingle | Simple shear Non-coaxiality Discrete element modelling Ai, Jun Langston, Paul A. Yu, Hai-Sui Discrete element modelling of material non-coaxiality in simple shear flows |
| title | Discrete element modelling of material non-coaxiality in simple shear flows |
| title_full | Discrete element modelling of material non-coaxiality in simple shear flows |
| title_fullStr | Discrete element modelling of material non-coaxiality in simple shear flows |
| title_full_unstemmed | Discrete element modelling of material non-coaxiality in simple shear flows |
| title_short | Discrete element modelling of material non-coaxiality in simple shear flows |
| title_sort | discrete element modelling of material non-coaxiality in simple shear flows |
| topic | Simple shear Non-coaxiality Discrete element modelling |
| url | https://eprints.nottingham.ac.uk/2403/ https://eprints.nottingham.ac.uk/2403/ https://eprints.nottingham.ac.uk/2403/ |