ORCID Profile
0000-0002-0197-569X
Current Organisation
Commonwealth Scientific and Industrial Research Organisation
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Medical Devices | Biomaterials | Biomechanical Engineering | Biomedical Engineering |
Education and Training Systems not elsewhere classified | Expanding Knowledge in Engineering | Expanding Knowledge in the Medical and Health Sciences
Publisher: Trans Tech Publications, Ltd.
Date: 07-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.846.476
Abstract: This paper aims at investigating the deformation and damage mechanisms of auxetic sandwich panels subjected to localised blast. The ability of self-densifying and adjusting to the loads, typical of auxetic structures, has been evaluated. A numerical model of the auxetic cellular composite panel has been developed to conduct statistical studies on different parameters (core geometry and material) using Taguchi design of experiment (DOE) method combined with general linear model (GLM) for analysis of variance (ANOVA). The optimisation has been conducted evaluating different parameters: energy absorption of the entire panel and deformation of the back facet were measured. The analysis of the numerical model of the core suggests the importance of the self-adapting mechanism of the auxetic structure under blast loading.
Publisher: MDPI AG
Date: 22-07-2021
DOI: 10.3390/MET11081167
Abstract: The microstructure–property relationship is critical for parts made using the emerging additive manufacturing process where highly localized cooling rates bestow spatially varying microstructures in the material. Typically, large temperature gradients during the build stage are known to result in significant thermally induced residual stresses in parts made using the process. Such stresses are influenced by the underlying local microstructures. Given the extensive range of variations in microstructures, it is useful to have an efficient method that can detect and quantify cause and effect. In this work, an efficient workflow within the machine learning (ML) framework for establishing microstructure–thermal stress correlations is presented. While synthetic microstructures and simulated properties were used for demonstration, the methodology may equally be applied to actual microstructures and associated measured properties. The dataset for ML consisted of images of synthetic microstructures along with thermal stress tensor fields simulated using a finite element (FE) model. The FE model considered various grain morphologies, crystallographic orientations, anisotropic elasticity and anisotropic thermal expansion. The overall workflow was ided into two parts. In the first part, image classification and clustering were performed for a sanity test of data. Accuracies of 97.33% and 99.83% were achieved using the ML based method of classification and clustering, respectively. In the second part of the work, convolution neural network model (CNN) was used to correlate the microstructures against various components and measures of stress. The target vectors of stresses consisted of in idual components of stress tensor, principal stresses and hydrostatic stress. The model was able to show a consistent correlation between various morphologies and components of thermal stress. The overall predictions by the model for all the microstructures resulted into R2≈0.96 for all the stresses. Such a correlation may be used for finding a range of microstructures associated with lower amounts of thermally induced stresses. This would allow the choice of suitable process parameters that can ensure that the desired microstructures are obtained, provided the relationship between those parameters and microstructures are also known.
Publisher: Springer International Publishing
Date: 2014
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.27
Abstract: ATM high pressure die casting technology (ATM) is a variant of the traditional high pressure die casting (HPDC) process and is distinguishable by its characteristic lean runners that increase process yields. Reduced raw material consumption helps ATM leave a smaller footprint on the environment by lowering greenhouse gas (GHG) emissions during primary processing of the alloys and in their melting and handling in the foundry. Further avenues for reducing GHG emissions are raised by the use of ATM technology which improves the integrity of castings - facilitating the adoption of lighter weight components in automobiles. In the present paper, reductions in GHG emissions achieved by ATM are illustrated with the aid of a commercial case study potential mass reduction opportunities for the automotive sector are explored with the aid of finite element analysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6RE00188B
Abstract: Continuous flow reactor for the hydrogenation of organic substrates using novel catalytic static mixers.
Publisher: Elsevier BV
Date: 04-2000
Publisher: American Institute of Aeronautics and Astronautics
Date: 05-01-2017
DOI: 10.2514/6.2017-0568
Publisher: MDPI AG
Date: 09-09-2021
DOI: 10.3390/MET11091425
Abstract: Microstructures encountered in the various metal additive manufacturing (AM) processes are unique because these form under rapid solidification conditions not frequently experienced elsewhere. Some of these highly nonequilibrium microstructures are subject to self-tempering or even forced to undergo recrystallisation when extra energy is supplied in the form of heat as adjacent layers are deposited. Further complexity arises from the fact that the same microstructure may be attained via more than one route—since many permutations and combinations available in terms of AM process parameters give rise to multiple phase transformation pathways. There are additional difficulties in obtaining insights into the underlying phenomena. For instance, the unstable, rapid and dynamic nature of the powder-based AM processes and the microscopic scale of the melt pool behaviour make it difficult to gather crucial information through in-situ observations of the process. Therefore, it is unsurprising that many of the mechanisms responsible for the final microstructures—including defects—found in AM parts are yet to be fully understood. Fortunately, however, computational modelling provides a means for recreating these processes in the virtual domain for testing theories—thereby discovering and rationalising the potential influences of various process parameters on microstructure formation mechanisms. In what is expected to be fertile ground for research and development for some time to come, modelling and experimental efforts that go hand in glove are likely to provide the fastest route to uncovering the unique and complex physical phenomena that determine metal AM microstructures. In this short Editorial, we summarise the status quo and identify research opportunities for modelling microstructures in AM. The vital role that will be played by machine learning (ML) models is also discussed.
Publisher: Springer International Publishing
Date: 2016
Publisher: Informa UK Limited
Date: 19-12-2014
Publisher: Springer Science and Business Media LLC
Date: 29-08-2007
Publisher: Elsevier BV
Date: 04-2015
Publisher: Informa UK Limited
Date: 07-2007
Publisher: IET
Date: 2012
DOI: 10.1049/CP.2012.0634
Publisher: Elsevier BV
Date: 06-1999
Publisher: Elsevier BV
Date: 10-2021
Publisher: Maney Publishing
Date: 04-2006
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.21
Abstract: In spite of die castings being amongst the highest volume items manufactured by the metalworking industry, the influence of high pressure die casting (HPDC) process parameters on greenhouse gas (GHG) emissions remains largely unreported. In this article, the authors discuss the effect of some HPDC process parameters on GHG emissions using cradle-to-gate life cycle assessment (LCA) for both aluminium and magnesium alloys. Although the impacts reduced with increasing yields in both cases, it was determined that the GHG impact of magnesium alloy HPDC was more sensitive to HPDC yield irrespective of the ratio of primary/secondary alloys in the melt charge. The reasons for this include a greater dependence of magnesium alloy HPDC on high-emitting primary processing and the use of the highly potent GHG SF6 for melting. For magnesium alloy HPDC, a decrease in quality assurance (QA) rejects and cycle times also reduced GHG emissions, although their influences were found to be an order lower than that of yield.
Publisher: MDPI AG
Date: 24-05-2021
DOI: 10.3390/MET11060858
Abstract: A new multi-stage three-dimensional transient computational model to simulate powder bed fusion (L-PBF) additive manufacturing (AM) processes is presented. The model uses the discrete element method (DEM) for powder flow simulation, an extended smoothed particle hydrodynamics (SPH) for melt pool dynamics and a semi-empirical microstructure evolution strategy to simulate the evolving temperature and microstructure of non-spherical Ti-6Al-4V powder grains undergoing L-PBF. The highly novel use of both DEM and SPH means that varied physics such as collisions between non-spherical powder grains during the coating process and heat transfer, melting, solidification and microstructure evolution during the laser fusion process can be simulated. The new capability is demonstrated by applying a complex representative laser scan pattern to a single-layer Ti-6Al-4V powder bed. It is found that the fast cooling rate primarily leads to a transition between the β and α martensitic phases. A minimal production of the α Widmanstatten phase at the outer edge of the laser is also noted due to an in situ heat treatment effect of the martensitic grains near the laser. This work demonstrates the potential of the coupled DEM/SPH computational model as a realistic tool to investigate the effect of process parameters such as powder morphology, laser scan speed and power characteristics on the Ti-6Al-4V powder bed microstructure.
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.1456
Abstract: The addition of a constriction in the melt flow path of high pressure die castings is discussed in terms of its influence on modifications to mechanical properties. It is shown through experimentation that the ultimate tensile strength and elongation to fracture of as-cast tensile specimens increased when the melt flowed through a constricted path. It is proposed that defect-forming inclusions were disintegrated more efficiently in the constricted runner through increased strain rates and turbulent dissipation rates. Increased turbulence is also presumed to be the cause for the greater dispersion of defects. The suggestions are supported with calculations aided by computational fluid dynamics simulations.
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.954
Abstract: Recently, heat treatment technologies have been developed by the CSIRO Light Metals Flagship in Australia that allow the 0.2% proof stress of conventional aluminum alloy high pressure diecastings (HPDC’s) to be more than doubled without encountering problems with blistering or dimensional instability [1,2]. A range of other properties may also be improved such as fatigue resistance, thermal conductivity and fracture resistance. However, the current commercial HPDC Al-Si-Cu alloys have not been developed to exploit heat treatment or to optimize these specific mechanical properties, and one potential limitation of heat treating HPDC’s is that fracture resistance may be reduced as strength is increased. The current paper presents the outcomes of a program aimed at developing highly castable, secondary Al-Si-Cu HPDC alloys which display significantly enhanced ductility and fracture resistance in both the as-cast and heat treated conditions. Kahn-type tear tests were conducted to compare the fracture resistance of the conventional A380 alloy with a selection of the newly developed compositions. A comparison has also been made with the current permanent mold cast aluminium alloys and it is shown that the new HPDC compositions typically display higher levels of both tensile properties and fracture resistance.
Publisher: IOP Publishing
Date: 23-06-2021
Abstract: The digital twin (DT) is a relatively new concept that is finding increased acceptance in industry. A DT is generally considered as comprising a physical entity, its virtual replica, and two-way digital data communications in-between. Its primary purpose is to leverage the process intelligence captured within digital models—or usually their faster-solving surrogates—towards generating increased value from the physical entities. The surrogate models are created using machine learning based on data obtained from the field, experiments and digital models, which may be physics-based or statistics-based. Anomaly detection and correction, and diagnostic closed-loop process control are ex les of how a process DT can be deployed. In the manufacturing industry, its use can achieve improvements in product quality and process productivity. Metal additive manufacturing (AM) stands to gain tremendously from the use of DTs. This is because the AM process is inherently chaotic, resulting in poor repeatability. However, a DT acting in a supervisory role can inject certainty into the process by actively keeping it within bounds through real-time control commands. Closed-loop feedforward control is achieved by observing the process through sensors that monitor critical parameters and, if there are any deviations from their respective optimal ranges, suitable corrective actions are triggered. The type of corrective action (e.g. a change in laser power or a modification to the scanning speed) and its magnitude are determined by interrogating the surrogate models. Because of their artificial intelligence (AI)-endowed predictive capabilities, which allow them to foresee a future state of the physical twin (e.g. the AM process), DTs proactively take context-sensitive preventative steps, whereas traditional closed-loop feedback control is usually reactive. Apart from assisting a build process in real-time, a DT can help with planning the build of a part by pinpointing the optimum processing window relevant to the desired outcome. Again, the surrogate models are consulted to obtain the required information. In this article, we explain how the application of DTs to the metal AM process can significantly widen its application space by making the process more repeatable (through quality assurance) and cheaper (by getting builds right the first time).
Publisher: MDPI AG
Date: 07-12-2017
DOI: 10.3390/MET7120549
Publisher: Elsevier BV
Date: 02-2023
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.1650
Abstract: On a metal surface covered with a moisture layer of variable thickness and shape, the dissolved oxygen may induce a spatial separation of the anodic and cathodic reactions on space-time scales characteristic of the roughness, droplet size and the local kinetics of the system. This leads to a spatio-temporal variations in species concentrations, current and potential over the metal surface and thus atmospheric corrosion. Here a fully three-dimensional transient model is developed that addresses the corrosion of a metal under an aerosol droplet. The effects of various parameters, such as exchange current densities, initial concentrations, shape and size of the droplet, and diffusivity of oxygen on ionic, potential and current distributions are investigated.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.331
Abstract: Recently, heat treatment technologies have been developed by the CSIRO Light Metals Flagship in Australia that allow the yield stress in conventional aluminium HPDC’s to be more than doubled without encountering problems with blistering or dimensional instability. These procedures involve a severely truncated solution treatment step conducted at lower than normal temperatures followed by quenching and artificial ageing. Typically, heat treated HPDC’s may display increases to the yield stress of around 80 to 100%, but a range of other properties may also be improved such as fatigue resistance, thermal conductivity and fracture resistance for some tempers. However, the HPDC alloys currently used worldwide have not been developed specifically for heat treatment or the optimization of specific properties. In particular, recent work in Al-Si-Cu HPDC alloys has identified ranges of alloys specifically for achieving yield strengths exceeding 400 MPa, or for high strength combined with elevated ductility levels. The role of alloying elements, composition limits and effects on microstructure development are discussed.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.33
Abstract: Melt flow and solidification within a die casting cavity is a complex process dependent in part on melt pressure (with or without intensification), melt velocity, melt flow path, thermal gradients within the die, die lubrication and melt viscosity. Casting defects such as short shots, cold shuts and shrinkage porosity can readily occur if casting conditions are not optimised. Shrinkage porosity in particular is difficult to eradicate from castings that comprise thick sections, since these sections will usually solidify late in the casting cycle and may be starved of melt supply during the critical solidification (and contraction) stage. The current work seeks to elucidate the influence of the melt shearing on the die casting process and demonstrates that the modifications made to the melt through introduction of a local constriction in the melt path can generate improvements in casting microstructure and reduce shrinkage porosity.
Publisher: Wiley
Date: 02-2014
Publisher: Elsevier BV
Date: 02-2009
Publisher: Elsevier BV
Date: 04-2017
Publisher: Trans Tech Publications Ltd.
Date: 15-07-2006
Publisher: Informa UK Limited
Date: 03-2010
Publisher: Trans Tech Publications, Ltd.
Date: 07-2006
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.519-521.351
Abstract: Conventionally produced high pressure die-cast (HPDC) components are not considered to be heat treatable because gases entrapped during the die-casting process expand during solution treatment causing unacceptable surface blistering. Components may also become dimensionally unstable. Both these effects prevent the heat treatment of die-castings as these phenomena are detrimental to the visual appearance, mechanical properties and utilisation of the component. Recent work has revealed a process window in which HPDC aluminium alloys that are capable of responding to age hardening may be successfully heat treated without encountering these problems. As a result, improvements of greater than 100% in the tensile properties are possible, when compared with the as-cast condition. The new heat treatment schedules are described for HPDC parts of different size and shape, the role of chemistry on ageing is discussed and microstructural development during heat treatment examined†.
Publisher: IET
Date: 2012
DOI: 10.1049/CP.2012.0622
Publisher: American Chemical Society (ACS)
Date: 13-07-2017
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.IMBIO.2008.07.025
Abstract: Langerhans cells and dermal dendritic cells migrate to the draining lymph nodes through dermal lymphatic vessels. They do so in the steady-state and under inflammatory conditions. Peripheral T cell tolerance or T cell priming, respectively, are the consequences of migration. The nature of dendritic cell-containing vessels was mostly defined by electron microscopy or by their lack of blood endothelial markers. Selective markers for murine lymph endothelium were hitherto rare or not available. Here, we utilised recently developed antibodies against the murine hyaluronan receptor, LYVE-1, to study the lymph vessel network in mouse skin in more detail. In hairless skin from the ears, lymph vessels were spread out in a horizontal plane. They formed anastomoses, and they possessed frequent blind endings that were occasionally open. Lymph vessels were wider than blood vessels, which were identified by their strong CD31 expression. In body wall skin LYVE-1 reactive vessels did not extend laterally but they ed straight down into the deeper dermis. There, they are connected to each other and formed a network similar to ear skin. The number and width of lymph vessels did not grossly change upon inflammatory stimuli such as skin explant culture or tape stripping. There were also no marked changes in caliber in response to the TLR 7/8 ligand Imiquimod. Double-labelling experiments of cultured skin showed that most of the strongly cell surface MHC II-expressing (i.e. activated) dendritic cells were confined to the lymph vessels. Langerin/CD207(+) cells within this population appeared later than dermal dendritic cells, i.e. langerin-negative cells. Comparable results were obtained after stimulating the skin in vivo with the TLR 7/8 ligand Imiquimod or by tape stripping. In untreated skin (i.e. steady state) a few MHC II(+) and Langerin/CD207(+) cells, presumably migrating skin dendritic cells including epidermal Langerhans cells, were consistently observed within the lymph vessels. The novel antibody reagents may serve as important tools to further study the dendritic cell traffic in the skin under physiological conditions as well as in conditions of adoptive dendritic cell transfer in immunotherapy.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Public Library of Science (PLoS)
Date: 22-10-2013
Publisher: Cambridge University Press (CUP)
Date: 1998
DOI: 10.1071/AS98176
Abstract: Since 1992, 60 large Kuiper Belt objects have been detected by ground-based telescopes. Previous surveys which have detected objects have searched approximately 60□° and detected objects with magnitudes 20·6 m R 25·0. However, the luminosity function of brighter Kuiper Belt objects is not well determined. The detection of brighter objects would improve our ability to determine the Kuiper Belt objects' surface composition and provide constraints on the population statistics of different formation mechanisms. This paper describes a survey of 12·0□° of sky near the ecliptic to a limiting magnitude of m R ∼ 21. A slow moving candidate was detected near the magnitude limit of the survey.
Publisher: Wiley
Date: 22-02-2013
Publisher: Elsevier BV
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 21-05-2009
Publisher: Springer Science and Business Media LLC
Date: 20-05-2014
Publisher: SAE International
Date: 20-04-2009
DOI: 10.4271/2009-01-0211
Publisher: Springer International Publishing
Date: 2017
Location: No location found
Location: Australia
Start Date: 09-2019
End Date: 07-2025
Amount: $4,000,000.00
Funder: Australian Research Council
View Funded Activity