ORCID Profile
0000-0003-2348-7563
Current Organisation
University of Adelaide
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Thomas Telford Ltd.
Date: 03-09-2012
Abstract: Localised failure of geomaterials involves deformation at two scales: a narrow localisation zone and the surrounding bulk. The behaviour associated with both scales should be properly taken into account in the development of constitutive models. This article presents a general constitutive modelling framework to connect these two scales, each of which is associated with a different stage of the material behaviour. It is demonstrated how this approach can be applied to any geomaterial model and how it could help obtain solutions independent of the spatial discretisation in numerical analysis.
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 05-2014
Publisher: Springer Science and Business Media LLC
Date: 30-06-2009
Publisher: Copernicus GmbH
Date: 29-11-2010
Abstract: Abstract. Ideally, a validation and assimilation scheme should maintain the physical principles embodied in the model and be able to evaluate and assimilate lower dimensional features (e.g., discontinuities) contained within a bulk simulation, even when these features are not directly observed or represented by model variables. We present such a scheme and suggest its potential to resolve or alleviate some outstanding problems that stem from making and applying required, yet often non-physical, assumptions and procedures in common operational data assimilation. As proof of concept, we use a sea-ice model with remotely sensed observations of leads in a one-step assimilation cycle. Using the new scheme in a sixteen day simulation experiment introduces model skill (against persistence) several days earlier than in the control run, improves the overall model skill and delays its drop off at later stages of the simulation. The potential and requirements to extend this scheme to different applications, and to both empirical and statistical multivariate and full cycle data assimilation schemes, are discussed.
Publisher: Elsevier BV
Date: 06-2018
Publisher: AIP Publishing
Date: 06-2022
DOI: 10.1063/5.0092726
Abstract: The behavior of submerged granular flow is strongly dependent on the solid volume fraction and the viscosity discontinuity over a wide range of flow regimes. To obtain a general description of this type of flow, this study proposes a new model to compute solid effective stresses of submerged granular materials across multiple flow regimes. Here, based on the critical state soil mechanics framework, a new equation is proposed to describe the evolution of elastic reference of materials caused by elastoplastic deformation. The evolution of elastic reference subsequently informs the development of static pressure, and together with the dynamic pressure computed using a well-established blended model, resulting in a new approach to compute the solid pressure induced by both dynamic and static effects. The proposed model is then implemented in the Eulerian–Eulerian approach using the finite volume method to simulate the collapses of submerged granular columns, covering different flow regimes from quasi-static to viscous depositions. Simulation results agreeing well with experimental and numerical data in the literature are a testament to the performance of a well-developed constitutive law. In addition, the simulation results comprehensibly demonstrate the important role of interstitial fluid flow as well as the initial solid volume fraction in the collapsing process across different flow regimes with different packing densities. Furthermore, the effects of initial volume fraction, fluid pressure, and phase interaction forces on the flow responses are also discussed.
Publisher: Wiley
Date: 2008
DOI: 10.1002/NAG.649
Publisher: Trans Tech Publications, Ltd.
Date: 05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.731
Abstract: We develop a novel constitutive modeling approach for the analysis of fracture propagation in quasi-brittle materials using the Material Point Method. The kinematics of constitutive models is enriched with an additional mode of localized deformation to take into account the strain discontinuity once cracking has occurred. The crack details therefore can be stored at material point level and there is no need to enrich the kinematics of finite elements to capture the localization caused by fracturing processes. This enhancement also removes the drawback of classical smeared crack approach in producing unphysical snapping back constitutive responses when the spatial resolution is not fine enough. All these facilitate the implementation of the new approach in the Material Point Method for analysis of large scale problems. Numerical ex les of fracture propagation are used to demonstrate the effectiveness and potentials of the new approach.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 11-2018
Publisher: Springer Science and Business Media LLC
Date: 19-05-2016
Publisher: Elsevier BV
Date: 12-2017
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 04-2007
Publisher: Elsevier BV
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 21-04-2016
Publisher: Springer Science and Business Media LLC
Date: 05-2006
Publisher: AIP Publishing
Date: 26-09-2018
DOI: 10.1063/1.5038903
Abstract: The objective of this study is to develop and test a coarse-grained molecular dynamics framework to model microscale multiphase systems with different inter-particle interactions and recover emerging thermodynamic and mechanical properties at the microscale. A water-vapor model and a fused silica model are developed to demonstrate the capability of our framework. The former can reproduce the water density and surface tension over a wide range of temperatures the latter can reproduce experimental density, tensile strength, and Young’s modulus of fused silica. Therefore, the deformable solid model is implemented in the proposed framework. Validations of spatial scaling methods for solid, liquid, and multiphase systems suggest that the proposed framework can be calibrated at an arbitrary microscale and used at a different length scale without recalibration. Different values of wettability for a solid-liquid-vapor system that is characterized by the contact angle can be achieved by changing the solid-liquid inter-particle potential. Thanks to these features, the proposed coarse-grained molecular dynamics framework can potentially find applications in modeling systems in which multiple phases coexist and have substantial interactions.
Publisher: Springer Science and Business Media LLC
Date: 30-06-2018
Publisher: Springer Science and Business Media LLC
Date: 13-08-2016
Publisher: Elsevier BV
Date: 12-2015
Publisher: Wiley
Date: 12-03-2019
DOI: 10.1002/NAG.2918
Publisher: American Geophysical Union (AGU)
Date: 06-08-2011
DOI: 10.1029/2011JB008265
Publisher: American Geophysical Union (AGU)
Date: 05-2013
DOI: 10.1002/JGRB.50193
Publisher: Trans Tech Publications, Ltd.
Date: 11-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.525-526.513
Abstract: Modern numerical techniques utilised to model crack propagation tend to be optimized for tracking the evolution of a single crack. Real fracture processes are however complex, involving the initiation and propagation of opening (activated) cracks, while other may close (deactivate) and undergo frictional dissipations. Accounting for the correct loss of energy (through debonding and friction) is essential to achieving a realistic description of the fracture process. One common strategy has been to make small adaptations to traditional techniques to tackle multiple cracking, in effect relying on extensive complicated computational algorithms. A typical ex le is the use of cohesive models in combination with the eXtended finite Element method where cracks, sometimes intersecting, need to be defined explicitly. In this study the Material Point Method is used for the analysis of fracture propagation. Crack states, as internal variables, are stored within the material points and mapped as strong discontinuities to the elements during the Lagrangian phase of the solution. Consequently, material points carrying cracks of different sizes and orientations are allowed to cohabit within the same element, yielding a natural description of the fracture/fragmentation process. The three-point bending test is used to demonstrate the features of the new approach.
Publisher: Springer Science and Business Media LLC
Date: 25-02-2016
Publisher: Elsevier BV
Date: 05-2010
Publisher: Springer Science and Business Media LLC
Date: 27-01-2018
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 10-2016
DOI: 10.1140/EPJE/I2016-16095-4
Abstract: A self-consistent model is developed to investigate attachment/detachment kinetics of two static, deformable microspheres with irregular surface and coated with flexible binding ligands. The model highlights how the microscale binding kinetics of these ligands as well as the attractive/repulsive potential of the charged surface affects the macroscale static deformed configuration of the spheres. It is shown that in the limit of smooth, neutrally charged surface (i.e., the dimensionless inverse Debye length, [Formula: see text]), interacting via elastic binders (i.e., the dimensionless stiffness coefficient, [Formula: see text]) the adhesion mechanics approaches the regime of application of the JKR theory, and in this particular limit, the contact radius, R
Publisher: American Geophysical Union (AGU)
Date: 11-2008
DOI: 10.1029/2008GL035086
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Society of Civil Engineers
Date: 06-07-2017
Publisher: Springer International Publishing
Date: 30-12-2014
Publisher: Elsevier BV
Date: 2016
Publisher: Springer Singapore
Date: 21-10-2017
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 10-2008
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 03-2019
Publisher: Trans Tech Publications, Ltd.
Date: 06-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.566.457
Abstract: The demand for energy-absorbing lightweight structures for impact applications in automotive, aerospace and defence industry is rapidly growing, posing a challenge for innovative engineering design to maintain lightweight without reducing damage tolerance and impact and shock absorption. In this context, biological materials offer a source of inspiration for the design of new materials. Nacre, commonly known as the mother-of-pearl, is a biological material that exhibits outstanding mechanical properties due to its hierarchical structure, which includes a brick-like pattern, layer waviness and interface. Although nacre is made of 95% of aragonite, a brittle material, its toughness is about 3000 larger than that of aragonite. Research addressing the behaviour of nacre-like engineering composites is limited and this work intends to contribute to the understanding of such materials under impact loading. In this paper, the study of the impact behaviour of layered nacre-like plates made of 1-mm thick tablets of aluminium alloy 7075 glued with toughened epoxy resin is performed using Abaqus/Explicit. A 9-mm steel spherical projectile with initial impact velocities in the range of 400-900 m/s is used. The epoxy material is modelled using a user-defined cohesive element that accounts for the experimentally observable increase in both strength and toughness in compression. Target thicknesses of 5 and 7 mm are modelled. The ballistic performance of bulk plates made of bulk Al-7075 is compared with that of nacre-like composite plates of the same thickness. It is found that the nacre-like structures performed slightly better than the bulk plate for high impact velocities with a reduction of about 9% in the residual velocity however, for lower impact velocities close to the ballistic limit, nacre-like plates performed worse than the bulk plate. The higher performance at higher impact velocities of the nacre-like composites is attributed to the hierarchical structure that enables both localized energy absorption by deformation of the metallic tablet and tablet interlocking due to the waviness and inter-layered delamination, which allows plastic deformation further away from the impact zone. It is concluded that nacre-like aluminium composite plates should be further investigated for their potential in designing protective structures because they could enable substantial improvements in weight-savings and in the ballistic performance of the structure. However, a quantitative assessment of their benefit warrants further numerical and experimental research.
Publisher: Wiley
Date: 2008
DOI: 10.1002/NAG.627
Publisher: Elsevier BV
Date: 05-2006
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Singapore
Date: 04-09-2020
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 06-2017
Publisher: Wiley
Date: 02-12-2009
DOI: 10.1002/NME.2790
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 10-2014
Publisher: American Society of Civil Engineers
Date: 06-07-2017
Publisher: Elsevier BV
Date: 02-2014
Publisher: Elsevier BV
Date: 2012
Publisher: Thomas Telford Ltd.
Date: 09-01-2014
Abstract: This letter extends an earlier theoretical and numerical analysis that aimed to improve predictions for the large-displacement end-bearing capacity of piles in sand by considering the boundary conditions applying to steady penetration and the effects of grain crushing via breakage mechanics. The earlier work led to good agreement with the end-bearing capacities, soil displacements and evolution of grain size distributions observed in experiments of penetrating model piles. The purpose of the current paper is to complement the previous evaluation through comparisons with more recently published calibration chamber measurements of the stresses surrounding instrumented model piles penetrating into dense silica sand. Encouraging agreement is demonstrated for the radial, circumferential and vertical stress components. Scope for further improvements is also identified.
Publisher: Springer Science and Business Media LLC
Date: 09-2005
Publisher: Thomas Telford Ltd.
Date: 04-2013
Abstract: A new formula is proposed for the end-bearing capacity of piles penetrating into crushable soils. The formula is based on a breakage mechanics model that accounts for the evolution of the grain size distribution (GSD) due to grain crushing with only physically meaningful parameters. The model is integrated using the finite-element method to study the penetration problem. Predictions of GSDs surrounding piles and pile end-bearing capacities are validated against experiments. Next, a parametric study is carried out to quantify the effects of grain crushing on the bearing capacity, and then to establish the formula. The predictive capability of the new formula is highlighted against predictions by previous formulae, which highlights its superior origins.
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 05-2019
Publisher: Springer Science and Business Media LLC
Date: 08-06-2007
Publisher: Springer Science and Business Media LLC
Date: 17-02-2018
Publisher: Wiley
Date: 2007
DOI: 10.1002/NAG.563
Publisher: Elsevier BV
Date: 07-2017
Publisher: Elsevier BV
Date: 10-2017
Publisher: Trans Tech Publications, Ltd.
Date: 05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.649
Abstract: Failure develops and propagates through a structure via a complex sequence of competing micro-mechanisms occurring simultaneously. While the active mechanism of surface debonding is the source of loss of stiffness and cohesion, friction between cracked surfaces, upon their closure, acts as a passive dissipation mechanism behind the quasi-brittleness and hence can increase the toughness of the material under favorable loading conditions. In order to numerically study damage propagation, the constitutive response must be able to faithfully capture, both qualitatively and quantitatively, one of the signature characteristic of failure: the energy dissipation. In this paper, we present an interface decohesive model for discrete fracture that is able to capture the apparent enhancement of interfacial properties that is observed when transverse compressive loads are applied. The model allows to seamlessly account for the additional frictional dissipation that occurs when the loading regime involves transverse compression, whether during debonding or after full delamination. This constitutive model is then used to successfully predict the response of realistic engineering structures under generalized loading conditions as demonstrated with the numerical simulation of a fiber push-out test.
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 03-2019
Publisher: American Society of Civil Engineers
Date: 06-07-2017
Publisher: Thomas Telford Ltd.
Date: 07-2022
Abstract: The formulation and calibration of constitutive models for geomaterials require material behaviour from experiments under a wide range of triaxial loading conditions. However, failure of geomaterials usually involves localisation of deformation that leads to very strong inhomogeneous behaviour. Therefore, the experimentally measured macro (specimen) behaviour is a mix between very different responses inside and outside the localisation zone and thus should not be used as a true representation of the material responses. This paper proposes a theoretical framework that provides links between mechanical responses inside and outside the localisation band, alongside their contributions toward the overall behaviour of a specimen undergoing localised deformation. This meso–macro connection allows the quantification of behaviour inside the localisation band, which is the main source of material inelasticity, from experimentally measured specimen behaviour. Correlation between the thickness of the localisation band and its behaviour is shown, bounded by a unique stress–deformation relationship describing the behaviour of an idealised zero-thickness localisation band.
Publisher: American Society of Civil Engineers
Date: 06-07-2017
Publisher: Elsevier BV
Date: 2014
Publisher: American Society of Civil Engineers
Date: 06-07-2017
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Giang Nguyen.