This page has only limited features, please log in for full access.

Unclaimed
Don Clucas
Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 11 May 2021 in Polymers
Reads 0
Downloads 0

Background: Polymer-based 3D Printed Injection Mould (3DIM) inserts are used as a cost-effective method for low volume injection moulding (50–500 parts). However, abrupt failure leading to a short tool life is a common shortcoming of 3DIM. Need: The underlying causes of raised feature failures on 3DIM are not well known. Failure is commonly attributed to bending or shearing of raised features on the tool. Understanding the causes may help in delaying the failure and increasing tool life. Approach: Tool failure was analysed from a first-principles perspective, using pressure and temperature fields as determined by mould flow simulation. Experimental results were also obtained for two types of tool material (Visijet M3-X and Digital ABS) with polycarbonate (Lexan 943A) as the part material. Findings: Results find against the idea that pin failure in 3DIM tools is caused by bending and shear failures induced by injection pressures. We also conclude that failure of raised features is not necessarily an abrupt failure as mentioned in the literature. Originality: The generally accepted explanation for the failure of raised features in 3DIM tooling is that injection pressures cause bending and shear failure. This paper disconfirms this notion on theoretical and experimental grounds.

ACS Style

Anurag Bagalkot; Dirk Pons; Digby Symons; Don Clucas. Analysis of Raised Feature Failures on 3D Printed Injection Moulds. Polymers 2021, 13, 1541 .

AMA Style

Anurag Bagalkot, Dirk Pons, Digby Symons, Don Clucas. Analysis of Raised Feature Failures on 3D Printed Injection Moulds. Polymers. 2021; 13 (10):1541.

Chicago/Turabian Style

Anurag Bagalkot; Dirk Pons; Digby Symons; Don Clucas. 2021. "Analysis of Raised Feature Failures on 3D Printed Injection Moulds." Polymers 13, no. 10: 1541.

Journal article
Published: 01 March 2021 in Advances in Materials Science
Reads 0
Downloads 0

A variety of tool shoulder designs comprising three families i.e. blade, spiral and circular shaped scrolls, were produced to improve the material flow and restrictions to avoid the tunnel void. The bobbin tools were manufactured by 3D printing additive manufacturing technology using solid filament. The butt weld joint was produced by each tool using plasticine as the workpiece material. The apparent surface features and bi-colour cross-sections provided a physical flow comparison among the shoulder designs. For the bobbin friction stir welding (BFSW), the tool shoulder with a three-spiral design produced the most stability with the best combination of the flow patterns on surface and cross-sections. The circular family tools showed a suitable intermixing on the surface pattern, while the blade scrolls showed better flow features within the cross-sections. The flow-driven effect of the shoulder features of the bobbin-tool design (inscribed grooves) was replicated by the 3D-printed tools and the analogue modelling of the weld samples. Similar flow patterns were achieved by dissimilar aluminium-copper weld, validating the accuracy of the analogue plasticine for the flow visualization of the bobbin friction stir welding.

ACS Style

A. Tamadon; D. J. Pons; K. Chakradhar; J. Kamboj; D. Clucas. 3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality. Advances in Materials Science 2021, 21, 27 -42.

AMA Style

A. Tamadon, D. J. Pons, K. Chakradhar, J. Kamboj, D. Clucas. 3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality. Advances in Materials Science. 2021; 21 (1):27-42.

Chicago/Turabian Style

A. Tamadon; D. J. Pons; K. Chakradhar; J. Kamboj; D. Clucas. 2021. "3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality." Advances in Materials Science 21, no. 1: 27-42.

Journal article
Published: 01 December 2020 in Advances in Materials Science
Reads 0
Downloads 0

Electron Backscatter Diffraction (EBSD) was used to determine microstructural evolution in AA6082-T6 welds processed by the Bobbin Friction Stir Welding (BFSW). This revealed details of grain-boundaries in different regions of the weld microstructure. Different polycrystalline transformations were observed through the weld texture. The Stirring Zone (SZ) underwent severe grain fragmentation and a uniform Dynamic Recrystallisation (DRX). The transition region experienced stored strain which changed the grain size and morphology via sub-grain-boundary transformations. Other observations were of micro-cracks, the presence of oxidization, and the presence of strain hardening associated with precipitates. Flow-arms in welds are caused by DRX processes including shear, and low and high angle grain boundaries. Welding variables affect internal flow which affects microstructural integrity. The shear deformation induced by the pin causes a non-uniform thermal and strain gradient across the weld region, leading to formation of mixed state transformation of grain morphologies through the polycrystalline structure. The grain boundary mapping represents the differences in DRX mechanism I different regions of the weld, elucidates by the consequences of the thermomechanical nature of the weld. The EBSD micrographs indicated that the localised stored strain at the boundary regions of the weld (e.g. flow-arms) has a more distinct effect in emergence of thermomechanical nonuniformities within the DRX microstructure.

ACS Style

A. Tamadon; D. J. Pons; D. Clucas. EBSD Characterization of Bobbin Friction Stir Welding of AA6082-T6 Aluminium Alloy. Advances in Materials Science 2020, 20, 49 -74.

AMA Style

A. Tamadon, D. J. Pons, D. Clucas. EBSD Characterization of Bobbin Friction Stir Welding of AA6082-T6 Aluminium Alloy. Advances in Materials Science. 2020; 20 (4):49-74.

Chicago/Turabian Style

A. Tamadon; D. J. Pons; D. Clucas. 2020. "EBSD Characterization of Bobbin Friction Stir Welding of AA6082-T6 Aluminium Alloy." Advances in Materials Science 20, no. 4: 49-74.

Journal article
Published: 16 June 2020 in Bioengineering
Reads 0
Downloads 0

To facilitate functional hydrogel part production using the indirect wax mould method, it is necessary to understand the relationships between materials, process and mould removal. This research investigated the thermophysical properties, wettability and surface roughness of wax template moulds in the production of cellulose hydrogel objects. Cellulose gel was thermally formed and shaped in three different wax moulds—high melting point paraffin, sacrificial investment casting wax and Solidscape® wax—by physical cross-linking of polymer networks of cellulose solution in NaOH/urea aqueous solvent. All three wax moulds were capable of casting cellulose hydrogel objects. Cellulose gelling time was reduced by increasing the temperature. Thus, the mould melting temperature had a direct effect on the gelling time. It was found that mould removal time varied based on the contact angle (CA) of the cellulose solution and the mould, and based on the melting point of the mould. A higher CA of cellulose solution on the wax moulds resulted in faster mould removal. When melting the wax in 90 °C water, high melting point paraffin, sacrificial investment casting and Solidscape® wax took about 3, 2 and 1½ h, respectively, to remove the moulds from the cellulose gel.

ACS Style

Hossein Najaf Zadeh; Tim Huber; Volker Nock; Conan Fee; Don Clucas. Complex Geometry Cellulose Hydrogels Using a Direct Casting Method. Bioengineering 2020, 7, 58 .

AMA Style

Hossein Najaf Zadeh, Tim Huber, Volker Nock, Conan Fee, Don Clucas. Complex Geometry Cellulose Hydrogels Using a Direct Casting Method. Bioengineering. 2020; 7 (2):58.

Chicago/Turabian Style

Hossein Najaf Zadeh; Tim Huber; Volker Nock; Conan Fee; Don Clucas. 2020. "Complex Geometry Cellulose Hydrogels Using a Direct Casting Method." Bioengineering 7, no. 2: 58.

Journal article
Published: 01 March 2020 in Advances in Materials Science
Reads 0
Downloads 0

The flow-inducing effect of the bobbin-tool features (tri-flat pin and scrolled shoulder) were replicated by a simple analogue model for aluminium welds by layered plasticine samples. Flow patterns of the weld zone were clarified by a typical stereomicroscopy instrument assisted by dark-field/bright-field illumination. The effects of the pin features, specifically threads and flats in centre of bond zone and scrolled shoulder in sides of stirred zone, were identified. This study shows that internal flow features for BFSW welds is transferable from the friction stir welding process to the functional metal forming processes such where the shearing can extensively affect the microstructure. The similarity between the flow pattern of the provided aluminium samples and the plasticine analogue can validate the accuracy of the flow model presented in this work.

ACS Style

A. Tamadon; D. J. Pons; D. Clucas. Analogue Modelling of Flow Patterns in Bobbin Friction Stir Welding by the Dark-Field/Bright-Field Illumination Method. Advances in Materials Science 2020, 20, 56 -70.

AMA Style

A. Tamadon, D. J. Pons, D. Clucas. Analogue Modelling of Flow Patterns in Bobbin Friction Stir Welding by the Dark-Field/Bright-Field Illumination Method. Advances in Materials Science. 2020; 20 (1):56-70.

Chicago/Turabian Style

A. Tamadon; D. J. Pons; D. Clucas. 2020. "Analogue Modelling of Flow Patterns in Bobbin Friction Stir Welding by the Dark-Field/Bright-Field Illumination Method." Advances in Materials Science 20, no. 1: 56-70.

Journal article
Published: 20 January 2020 in Applied Mechanics
Reads 0
Downloads 0

Material flow transportation around the rotating tool and the mass deposition at the backside of the tool are critical characteristics of friction stir welding. To achieve an optimized weld structure, the history of the plastic deformation needs to be identified with a flow-based elucidation. In this study, an analogue model was applied to evaluate the formation of a banded structure using the bobbin tool, with a focus on the interaction between the tool-workpiece. The flow visualization in plasticine analogue was validated in comparison with the aluminium welds. The plastic flow mechanism was visualized both, at the surface and the cross-section of the weld-seam. The cross-section of the weld shows the details of the formation of tunnel voids, caused by the failure of the flow regimes. A physical model of the material flow was proposed to explain the formation mechanism of the tunnel void as a discontinuity during the mass refilling at the rear of the tool.

ACS Style

Abbas Tamadon; Dirk J. Pons; Don Clucas. Flow-Based Anatomy of Bobbin Friction-Stirred Weld; AA6082-T6 Aluminium Plate and Analogue Plasticine Model. Applied Mechanics 2020, 1, 3 -19.

AMA Style

Abbas Tamadon, Dirk J. Pons, Don Clucas. Flow-Based Anatomy of Bobbin Friction-Stirred Weld; AA6082-T6 Aluminium Plate and Analogue Plasticine Model. Applied Mechanics. 2020; 1 (1):3-19.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Don Clucas. 2020. "Flow-Based Anatomy of Bobbin Friction-Stirred Weld; AA6082-T6 Aluminium Plate and Analogue Plasticine Model." Applied Mechanics 1, no. 1: 3-19.

Journal article
Published: 20 December 2019 in Applied System Innovation
Reads 0
Downloads 0

The potential position for tunnel defect within the structure of bobbin-tool friction stir welds was studied by analogue modelling. The welding process was simulated on layered plasticine slabs instead, compared to the aluminum plates. Observations in the modelled structure showed a high possibility for a continuous channelled discontinuity, like a tunnel-shaped void defect, in the entry zone of the weld, which mirrors the metal welding. The anatomy of tunnel defect in the entry zone was explained according to the mechanics of material during the plastic deformation process.

ACS Style

Abbas Tamadon; Dirk J. Pons; Don Clucas. Structural Anatomy of Tunnel Void Defect in Bobbin Friction Stir Welding, Elucidated by the Analogue Modelling. Applied System Innovation 2019, 3, 2 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Don Clucas. Structural Anatomy of Tunnel Void Defect in Bobbin Friction Stir Welding, Elucidated by the Analogue Modelling. Applied System Innovation. 2019; 3 (1):2.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Don Clucas. 2019. "Structural Anatomy of Tunnel Void Defect in Bobbin Friction Stir Welding, Elucidated by the Analogue Modelling." Applied System Innovation 3, no. 1: 2.

Communication
Published: 07 November 2019 in Technologies
Reads 0
Downloads 0

Bobbin Friction Stir Welding (BFSW) is a thermomechanical process containing severe plastic deformation by mechanical stirring and Dynamic Recrystallization (DRX) during recooling. Here we report the three-dimensional characteristics of the micro-flow patterns within the aluminium weld structure. The Surface topography observations by Atomic Force Microscopy (AFM) show the stirred-induced microstructural evolution where the rearrangement of dislocations at the sub-grain scale, and the subsequent High- and Low-Angle Grain Boundaries (HAGBs, LAGBs) exhibit specific alterations in grain size and morphology of the weld texture. The dislocations interaction in different regions of the weld structure also was observed in correlation to the thermomechanical behaviour of the BFSW process. These micro-flow observations within the weld breadth give a new insight into the thermomechanical characteristics of the FSW process during the stirring action where the plastic flow has a key role in the formation of the weld region distinct from the base metal.

ACS Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Pons. AFM Characterization of Stir-Induced Micro-Flow Features within the AA6082-T6 BFSW Welds. Technologies 2019, 7, 80 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Don Clucas, Pons. AFM Characterization of Stir-Induced Micro-Flow Features within the AA6082-T6 BFSW Welds. Technologies. 2019; 7 (4):80.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Pons. 2019. "AFM Characterization of Stir-Induced Micro-Flow Features within the AA6082-T6 BFSW Welds." Technologies 7, no. 4: 80.

Journal article
Published: 14 October 2019 in Rapid Prototyping Journal
Reads 0
Downloads 0

Purpose Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts. Design/methodology/approach A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues. Findings Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time. Originality/value This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.

ACS Style

Anurag Bagalkot; Dirk Pons; Don Clucas; Digby Symons. A methodology for setting the injection moulding process parameters for polymer rapid tooling inserts. Rapid Prototyping Journal 2019, 25, 1493 -1505.

AMA Style

Anurag Bagalkot, Dirk Pons, Don Clucas, Digby Symons. A methodology for setting the injection moulding process parameters for polymer rapid tooling inserts. Rapid Prototyping Journal. 2019; 25 (9):1493-1505.

Chicago/Turabian Style

Anurag Bagalkot; Dirk Pons; Don Clucas; Digby Symons. 2019. "A methodology for setting the injection moulding process parameters for polymer rapid tooling inserts." Rapid Prototyping Journal 25, no. 9: 1493-1505.

Journal article
Published: 01 October 2019 in Materials
Reads 0
Downloads 0

One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process.

ACS Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Kamil Sued. Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation. Materials 2019, 12, 3215 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Don Clucas, Kamil Sued. Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation. Materials. 2019; 12 (19):3215.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Kamil Sued. 2019. "Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation." Materials 12, no. 19: 3215.

Journal article
Published: 28 September 2019 in Metals
Reads 0
Downloads 0

Bobbin friction stir welding with a double-sided tool configuration produces a symmetrical solid-state joint. However, control of the process parameters to achieve defect-free welds is difficult. The internal flow features of the AA6082-T6 butt-joints in bobbin friction stir welding were evaluated using a set of developed reagents and optical microscopy. The key findings are that the dark curved patterns (conventionally called 'flow-arms'), are actually oxidation layers at the advancing side, and at the retreating side are elongated grains with a high-density of accumulation of sub-grain boundaries due to dynamic recrystallization. A model of discontinuous flow within the weld is proposed, based on the microscopic observations. It is inferred that the internal flow is characterized by packets of material ('flow patches') being transported around the pin. At the retreating side they experience high localized shearing at their mutual boundaries, as evidenced in high density of sub-grain boundaries. Flow patches at the advancing side are stacked on each other and exposed to oxidization.

ACS Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Kamil Sued; Pons; Sued. Internal Material Flow Layers in AA6082-T6 Butt-Joints during Bobbin Friction Stir Welding. Metals 2019, 9, 1059 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Don Clucas, Kamil Sued, Pons, Sued. Internal Material Flow Layers in AA6082-T6 Butt-Joints during Bobbin Friction Stir Welding. Metals. 2019; 9 (10):1059.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Don Clucas; Kamil Sued; Pons; Sued. 2019. "Internal Material Flow Layers in AA6082-T6 Butt-Joints during Bobbin Friction Stir Welding." Metals 9, no. 10: 1059.

Journal article
Published: 11 September 2019 in Applied Sciences
Reads 0
Downloads 0

Cardiovascular diseases (CVDs) are one of the leading causes of death globally. In-vitro measurement of blood flow in compliant arterial phantoms can provide better insight into haemodynamic states and therapeutic procedures. However, current fabrication techniques are not capable of producing thin-walled compliant phantoms of complex shapes. This study presents a new approach for the fabrication of compliant phantoms suitable for optical measurement. Two 1.5× scaled models of the ascending aorta, including the brachiocephalic artery (BCA), were fabricated from silicone elastomer Sylgard-184. The initial phantom used the existing state of the art lost core manufacturing technique with simple end supports, an acrylonitrile butadiene styrene (ABS) additive manufactured male mould and Ebalta-milled female mould. The second phantom was produced with the same method but used more rigid end supports and ABS male and female moulds. The wall thickness consistency and quality of resulting stereoscopic particle image velocimetry (SPIV) were used to verify the fidelity of the phantom for optical measurement and investigation of physiological flow fields. However, the initial phantom had a rough surface that obscured SPIV analysis and had a variable wall thickness (range = 0.815 mm). The second phantom provided clear particle images and had a less variable wall thickness (range = 0.317 mm). The manufacturing method developed is suitable for fast and cost-effective fabrication of different compliant arterial phantom geometries.

ACS Style

Sina G. Yazdi; Larissa Huetter; Paul D. Docherty; Petra N. Williamson; Don Clucas; Mark Jermy; Patrick H. Geoghegan. A Novel Fabrication Method for Compliant Silicone Phantoms of Arterial Geometry for Use in Particle Image Velocimetry of Haemodynamics. Applied Sciences 2019, 9, 3811 .

AMA Style

Sina G. Yazdi, Larissa Huetter, Paul D. Docherty, Petra N. Williamson, Don Clucas, Mark Jermy, Patrick H. Geoghegan. A Novel Fabrication Method for Compliant Silicone Phantoms of Arterial Geometry for Use in Particle Image Velocimetry of Haemodynamics. Applied Sciences. 2019; 9 (18):3811.

Chicago/Turabian Style

Sina G. Yazdi; Larissa Huetter; Paul D. Docherty; Petra N. Williamson; Don Clucas; Mark Jermy; Patrick H. Geoghegan. 2019. "A Novel Fabrication Method for Compliant Silicone Phantoms of Arterial Geometry for Use in Particle Image Velocimetry of Haemodynamics." Applied Sciences 9, no. 18: 3811.

Journal article
Published: 02 January 2019 in Processes
Reads 0
Downloads 0

Background—Polymer rapid tooling (PRT) inserts for injection molding (IM) are a cost-effective method for prototyping and low-volume manufacturing. However, PRT inserts lack the robustness of steel inserts, leading to progressive deterioration and failure. This causes quality issues and reduced part numbers. Approach—Case studies were performed on PRT inserts, and different failures were observed over the life of the tool. Parts molded from the tool were examined to further understand the failures, and root causes were identified. Findings—Critical parameters affecting the tool life, and the effect of these parameters on different areas of tool are identified. A categorization of the different failure modes and the underlying mechanisms are presented. The main failure modes are: surface deterioration; surface scalding; avulsion; shear failure; bending failure; edge failure. The failure modes influence each other, and they may be connected in cascade sequences. Originality—The original contributions of this work are the identification of the failure modes and their relationships with the root causes. Suggestions are given for prolonging tool life via design practices and molding parameters.

ACS Style

Anurag Bagalkot; Dirk Pons; Digby Symons; Don Clucas. Categorization of Failures in Polymer Rapid Tools Used for Injection Molding. Processes 2019, 7, 17 .

AMA Style

Anurag Bagalkot, Dirk Pons, Digby Symons, Don Clucas. Categorization of Failures in Polymer Rapid Tools Used for Injection Molding. Processes. 2019; 7 (1):17.

Chicago/Turabian Style

Anurag Bagalkot; Dirk Pons; Digby Symons; Don Clucas. 2019. "Categorization of Failures in Polymer Rapid Tools Used for Injection Molding." Processes 7, no. 1: 17.

Journal article
Published: 01 September 2018 in Simulation Modelling Practice and Theory
Reads 0
Downloads 0

This paper presents 3D modelling and simulation of a non-holonomic omnidirectional mobile robot, MARIO – Mobile Autonomous Rover for Intelligent Operations, using the Gazebo simulator and Robot Operating System (ROS), aiming for offline programming and system performance analysis. For this purpose, MARIO as a four wheel active driving/steering (4WD4S) platform has been modelled and simulated based on the physical developed model. Gazebo enables simulation of the world environment, physical model, sensors and control system through the Unified Robot Description Format (URDF) file. ROS is interfaced with Gazebo which allows utilization and implementation of different robotic software and tools on the simulated robot. This presented approach allows development, testing and validation of MARIO and required software before implementation on the real system. The presented approach also provides the essential theory and practice for robotic system specialists in modelling and simulation of ground mobile robotic systems using Gazebo simulator and ROS.

ACS Style

Mostafa Sharifi; Xiaoqi Chen; Christopher Pretty; Don Clucas; Erwan Cabon-Lunel. Modelling and simulation of a non-holonomic omnidirectional mobile robot for offline programming and system performance analysis. Simulation Modelling Practice and Theory 2018, 87, 155 -169.

AMA Style

Mostafa Sharifi, Xiaoqi Chen, Christopher Pretty, Don Clucas, Erwan Cabon-Lunel. Modelling and simulation of a non-holonomic omnidirectional mobile robot for offline programming and system performance analysis. Simulation Modelling Practice and Theory. 2018; 87 ():155-169.

Chicago/Turabian Style

Mostafa Sharifi; Xiaoqi Chen; Christopher Pretty; Don Clucas; Erwan Cabon-Lunel. 2018. "Modelling and simulation of a non-holonomic omnidirectional mobile robot for offline programming and system performance analysis." Simulation Modelling Practice and Theory 87, no. : 155-169.

Journal article
Published: 02 July 2018 in Journal of Manufacturing and Materials Processing
Reads 0
Downloads 0

A 3D printer was developed for the 3D printing of cellulose hydrogels using open source software and simple 3D printer hardware. Using a temperature-based sol-gel transition of cellulose dissolved in aqueous solutions of sodium hydroxide (NaOH) and urea, a three-dimensional gel can be created by moving a focused laser beam across a bath of the cellulose solution and lowering the print stage after every layer. A line width of 100–150 µm and layer thickness of 25 µm of the printed part could be achieved. No delamination between printed layers occurred and no additional support material was needed to create free hanging structures due to suspending the printed part in printing liquid. By adding cellulose powder to the solution, the gelation temperature, the gel strength and stiffness can be manipulated while maintaining a high internal porosity of the gel. A laser power of 100 mW was found to produce the highest quality print with an accurate representation of the previously designed part. Lower power settings (80 mW) produced insufficient gelation and as a result reduced print accuracy while higher power settings (120 mW) caused the gel to burn.

ACS Style

Tim Huber; Don Clucas; Mathieu Vilmay; Birte Pupkes; James Stuart; Simone DiMartino; Conan Fee. 3D Printing Cellulose Hydrogels Using LASER Induced Thermal Gelation. Journal of Manufacturing and Materials Processing 2018, 2, 42 .

AMA Style

Tim Huber, Don Clucas, Mathieu Vilmay, Birte Pupkes, James Stuart, Simone DiMartino, Conan Fee. 3D Printing Cellulose Hydrogels Using LASER Induced Thermal Gelation. Journal of Manufacturing and Materials Processing. 2018; 2 (3):42.

Chicago/Turabian Style

Tim Huber; Don Clucas; Mathieu Vilmay; Birte Pupkes; James Stuart; Simone DiMartino; Conan Fee. 2018. "3D Printing Cellulose Hydrogels Using LASER Induced Thermal Gelation." Journal of Manufacturing and Materials Processing 2, no. 3: 42.

Journal article
Published: 23 May 2018 in Metals
Reads 0
Downloads 0

Bobbin friction stir welding (BFSW), with its fully penetrated pin and double-sided shoulder, can provide high rates of heat generation. This produces solid-state thermo-mechanical grain refinement. In this paper, the microstructure evolution of the welded joints of AA6082-T6 obtained using BFSW process was investigated with a focus on grain refinement. Two sheets of the AA6082-T6 alloy were butt-welded with a fixed-gap bobbin tool. The microstructure at a mid-weld transverse cross-section was evaluated using optical microscopy and electron backscatter diffraction (EBSD). Significant grain refinement was observed, with a decrease in grain size from 100 μm in directional columnar grain morphology of the base metal, to an ultrafine size—less than 10 μm—for the equiaxed grains in the stirring zone. The EBSD results showed that with BFSW processing, secondary phase precipitation patterns were produced that are distinct from the primary artificial age-hardening precipitates created by the T6 tempering cycle. The severe plastic deformation and heat generation appear to accelerate dynamic recrystallization and precipitation during the BFSW process. The microstructural studies confirmed that the BFSW process can provide a highly efficient thermodynamically activated grain refinement in the solid-state without requiring additional processes such as heat treatment or external means of grain refinement.

ACS Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. Thermomechanical Grain Refinement in AA6082-T6 Thin Plates under Bobbin Friction Stir Welding. Metals 2018, 8, 375 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Kamil Sued, Don Clucas. Thermomechanical Grain Refinement in AA6082-T6 Thin Plates under Bobbin Friction Stir Welding. Metals. 2018; 8 (6):375.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. 2018. "Thermomechanical Grain Refinement in AA6082-T6 Thin Plates under Bobbin Friction Stir Welding." Metals 8, no. 6: 375.

Journal article
Published: 07 March 2018 in Energies
Reads 0
Downloads 0

Unlike internal combustion engines, Stirling engines can be designed to work with many drive mechanisms based on the three primary configurations, alpha, beta and gamma. Hundreds of different combinations of configuration and mechanical drives have been proposed. Few succeed beyond prototypes. A reason for poor success is the use of inappropriate configuration and drive mechanisms, which leads to low power to weight ratio and reduced economic viability. The large number of options, the lack of an objective comparison method, and the absence of a selection criteria force designers to make random choices. In this article, the pressure—volume diagrams and compression ratios of machines of equal dimensions, using the main (alpha, beta and gamma) crank based configurations as well as rhombic drive and Ross yoke mechanisms, are obtained. The existence of a direct relation between the optimum compression ratio and the temperature ratio is derived from the ideal Stirling cycle, and the usability of an empirical low temperature difference compression ratio equation for high temperature difference applications is tested using experimental data. It is shown that each machine has a different compression ratio, making it more or less suitable for a specific application, depending on the temperature difference reachable.

ACS Style

Jose Egas; Don M. Clucas. Stirling Engine Configuration Selection. Energies 2018, 11, 584 .

AMA Style

Jose Egas, Don M. Clucas. Stirling Engine Configuration Selection. Energies. 2018; 11 (3):584.

Chicago/Turabian Style

Jose Egas; Don M. Clucas. 2018. "Stirling Engine Configuration Selection." Energies 11, no. 3: 584.

Journal article
Published: 05 January 2018 in Metals
Reads 0
Downloads 0

Bobbin friction stir welding (BFSW) is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause uncontrolled weld defects. The entry zone and the exit zone consist of two discontinuity-defects and removing them is one of the current challenges for improving the weld quality. In the present research, the characteristic features of the entry and exit defects in the weld structure and formation mechanism of them during the BFSW processing was investigated. Using stacked layers of multi-colour plasticine the material flow, analogous to metal flow, can be visualised. By using different colours as the path markers of the analogue model, the streamline flow can be easily delineated in the discontinuity defects compared with the metal welds. AA6082-T6 aluminium plates and multi-layered plasticine slabs were employed to replicate the entry-exit defects in the metal weld and analogue samples. The fixed-bobbin tool utilized for this research was optimized by adding a thread feature and tri-flat geometry to the pin and closed-end spiral scrolls on both shoulder surfaces. Samples were processed at different rotating and longitudinal speeds to show the degree of dependency on the welding parameters for the defects. The analogue models showed that the entry zone and the exit zone of the BFSW are affected by the inhomogeneity of the material flow regime which causes the ejection or disruption of the plastic flow in the gap between the bobbin shoulders. The trial aluminium welds showed that the elimination of entry-exit defects in the weld body is not completely possible but the size of the defects can be minimized by modification of the welding parameters. For the entry zone, the flow pattern evolution suggested formation mechanisms for a sprayed tail, island zone and discontinuity-channel. For the exit zone a keyhole-shaped discontinuity is discussed as a structural defect.

ACS Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding. Metals 2018, 8, 33 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Kamil Sued, Don Clucas. Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding. Metals. 2018; 8 (1):33.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. 2018. "Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding." Metals 8, no. 1: 33.

Journal article
Published: 11 October 2017 in Metals
Reads 0
Downloads 0

BACKGROUND—The solid-phase joining of A6082-T6 plates by bobbin friction stir welding (BFSW) is problematic. Better methods are needed to evaluate the microstructural evolution of the weld. However, conventional Al reagents (e.g., Keller’s and Kroll’s) do not elucidate the microstructure satisfactorily, specifically regarding grain size and morphology within the weld region. APPROACH—We developed innovative etchants for metallographic observations for optical microscopy. RESULTS—The macrostructure and microstructure of A6082-T6 BFSW welds were clearly demonstrated by optical microscopy analysis. The microetching results demonstrated different microstructures of the Stir Zone (S.Z) distinct from the Base Metal (B.M) and Heat Affected Zone (HAZ) & Thermo-mechanical Affected Zone (TMAZ). The micrographs showed a significant decrease in grain size from 100 μm in B.M to ultrafine 4–10 μm grains for the S.Z. Also, the grain morphology changed from directional columnar in the B.M to equiaxed in the S.Z. Furthermore, thermomechanical recrystallization was observed by the morphological flow of the grain distortion in HAZ and TMAZ. The etchants also clearly show the polycrystalline structure, microflow patterns, and the incoherent interface around inclusion defects. ORIGINALITY—Chemical compositions are identified for a suite of etchant reagents for metallographic examination of the friction-stir welded A6082-T6 alloy. The reagents have made it possible to reveal microstructures not previously evident with optical microscopy.

ACS Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds. Metals 2017, 7, 423 .

AMA Style

Abbas Tamadon, Dirk J. Pons, Kamil Sued, Don Clucas. Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds. Metals. 2017; 7 (10):423.

Chicago/Turabian Style

Abbas Tamadon; Dirk J. Pons; Kamil Sued; Don Clucas. 2017. "Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds." Metals 7, no. 10: 423.

Journal article
Published: 01 March 2017 in Energy Procedia
Reads 0
Downloads 0
ACS Style

Don Clucas; Jose Egas. Additive Manufactured Functional Prime Mover. Energy Procedia 2017, 110, 136 -142.

AMA Style

Don Clucas, Jose Egas. Additive Manufactured Functional Prime Mover. Energy Procedia. 2017; 110 ():136-142.

Chicago/Turabian Style

Don Clucas; Jose Egas. 2017. "Additive Manufactured Functional Prime Mover." Energy Procedia 110, no. : 136-142.