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Subject = Additive manufacturing;
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Displaying Results 1 - 25 of 28 on page 1 of 2
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3D-Printed Peptide-Hydrogel Nanoparticle Composites for Surface-Enhanced Raman Spectroscopy Sensing
(2019)
Almohammed, Sawsan; Alruwaili, Maha; Reynaud, Emmanuel G.; Redmond, Gareth; Rice, James...
3D-Printed Peptide-Hydrogel Nanoparticle Composites for Surface-Enhanced Raman Spectroscopy Sensing
(2019)
Almohammed, Sawsan; Alruwaili, Maha; Reynaud, Emmanuel G.; Redmond, Gareth; Rice, James H.; Rodriguez, Brian J.
Abstract:
Precise control over the arrangement of plasmonic nanomaterials is critical for label-free single-molecule surface-enhanced Raman spectroscopy (SERS)-based sensing applications. SERS templates should provide high sensitivity and reproducibility and be cost-effective and easy to prepare. Additive manufacturing by extrusion-based three-dimensional (3D) printing is an emerging technique for the spatial arrangement of nanomaterials and is a method that may satisfy these SERS template requirements. In this work, we use 3D printing to produce sensitive and reproducible SERS templates using a fluorenylmethyloxycarbonyl diphenylalanine (Fmoc-FF) hydrogel loaded with silver or gold nanoparticles. The Fmoc-FF template allows the detection of low Raman cross-section molecules such as adenine at concentrations as low as 100 pM.
Enterprise Ireland
European Commission Horizon 2020
Science Foundation Ireland
The Ministry of Higher Education of Saudi Arabia under the King Abdullah S...
http://hdl.handle.net/10197/10962
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A novel paradigm for managing the product development process utilising blockchain technology principles
(2020)
Papakostas, Nikolaos; Newell, Anthony; Hargaden, Vincent
A novel paradigm for managing the product development process utilising blockchain technology principles
(2020)
Papakostas, Nikolaos; Newell, Anthony; Hargaden, Vincent
Abstract:
The product conceptualisation, design and manufacturing phases are becoming increasingly complex, since more available resources, stakeholders and sophisticated technologies are involved during product development. The exchange and management of product-related information is often a challenging task, affecting significantly the intellectual property protection process as well as the distinction of roles among stakeholders. This paper proposes a conceptual framework that utilises blockchain technology principles for managing product development information and processes with the goal of providing new approaches to extending the functionality of product data management systems. A test case focusing on products developed with additive manufacturing technologies is presented.
European Commission - European Regional Development Fund
Science Foundation Ireland
http://hdl.handle.net/10197/11738
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A radiopaque nanoparticle-based ink using PolyJet 3D printing for medical applications
(2021)
Shannon, Alice; O'Connell, Aine; O'Sullivan, Aidan; Byrne, Michael; Clifford,...
A radiopaque nanoparticle-based ink using PolyJet 3D printing for medical applications
(2021)
Shannon, Alice; O'Connell, Aine; O'Sullivan, Aidan; Byrne, Michael; Clifford, Seamus; O'Sullivan, Kevin Jeremiah; O'Sullivan, Leonard
Abstract:
The full text of this article will not be available in ULIR until the embargo expires on the 16/12/2021
The aim of this study was to develop a 3D printable radiopaque ink and successfully print a finished artifact. Radiopaque 3D printing would be hugely beneficial to improve the visibility of medical devices and implants, as well as allowing more realistic phantoms and calibration aids to be produced. Most 3D printing technologies are polymer based. Polymers are naturally radiolucent, allowing X-rays to pass through, showing up as faint dark gray regions on X-ray detectors, as for soft tissues. During this study, a 3D printable ultraviolet (UV) curable resin containing zirconium oxide (ZrO2) nanoparticles was developed. 5 wt.% ZrO2 was dispersed in a base resin using a high-shear mixer. Particles remained in suspension for 6–8 h at room temperature, allowing time for 3D printing. A model of a hand including radiopaque bones and a test block demonstrating a range of internal radi...
http://hdl.handle.net/10344/9680
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A review of factors affecting the mechanical properties of maraging steel 300 fabricated via laser powder bed fusion
(2020)
Mooney, Barry; Kourousis, Kyriakos I.
A review of factors affecting the mechanical properties of maraging steel 300 fabricated via laser powder bed fusion
(2020)
Mooney, Barry; Kourousis, Kyriakos I.
Abstract:
Maraging steel is an engineering alloy which has been widely employed in metal additive manufacturing. This paper examines manufacturing and post-processing factors affecting the properties of maraging steel fabricated via laser powder bed fusion (L-PBF). It covers the review of published research findings on how powder quality feedstock, processing parameters, laser scan strategy, build orientation and heat treatment can influence the microstructure, density and porosity, defects and residual stresses developed on L-PBF maraging steel, with a focus on the maraging steel 300 alloy. This review offers an evaluation of the resulting mechanical properties of the as-built and heat-treated maraging steel 300, with a focus on anisotropic characteristics. Possible directions for further research are also identified.
http://hdl.handle.net/10344/9273
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A review of the as-built SLM Ti-6Al-4V mechanical properties towards achieving fatigue resistant designs
(2018)
Agius, Dylan J.; Kourousis, Kyriakos I.; Wallbrink, Chris
A review of the as-built SLM Ti-6Al-4V mechanical properties towards achieving fatigue resistant designs
(2018)
Agius, Dylan J.; Kourousis, Kyriakos I.; Wallbrink, Chris
Abstract:
Ti-6Al-4V has been widely used in both the biomedical and aerospace industry, due to its high strength, corrosion resistance, high fracture toughness and light weight. Additive manufacturing (AM) is an attractive method of Ti-6Al-4V parts’ fabrication, as it provides a low waste alternative for complex geometries. With continued progress being made in SLM technology, the influence of build layers, grain boundaries and defects can be combined to improve further the design process and allow the fabrication of components with improved static and fatigue strength in critical loading directions. To initiate this possibility, the mechanical properties, including monotonic, low and high cycle fatigue and fracture mechanical behaviour, of machined as-built SLM Ti-6Al-4V, have been critically reviewed in order to inform the research community. The corresponding crystallographic phases, defects and layer orientations have been analysed to determine the influence of these features on the mecha...
http://hdl.handle.net/10344/6485
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Additive Manufacture of Composite Soft Pneumatic Actuators
(2018)
Byrne, Oisín; Coulter, Fergal; Glynn, Mark; Jones, James F. X.; Ní Annaidh, Aisling; O&...
Additive Manufacture of Composite Soft Pneumatic Actuators
(2018)
Byrne, Oisín; Coulter, Fergal; Glynn, Mark; Jones, James F. X.; Ní Annaidh, Aisling; O'Cearbhaill, Eoin D.; Holland, Dónal P
Abstract:
This article presents a direct additive manufacturing method for composite material soft pneumatic actuators that are capable of performing a range of programmable motions. Commonly, molding is the method used to manufacture soft fluidic actuators. This is material, labor, and time intensive and lacks the design freedom to produce custom actuators efficiently. This article proposes an alternative semiautomated method of designing and manufacturing composite soft actuators. An affordable, open-source, desktop three-dimensional (3D) printer was modified into a four-axis, combined, fused deposition modeling, and paste extrusion printer. A Grasshopper 3D algorithm was devised to implement custom actuator designs according to user inputs, resulting in a G-code print file. Bending, contracting, and twisting motion actuators were parametrically designed and subsequently additively manufactured from silicone and thermoplastic elastomer (TPE) materials. Experimental testing was completed on ...
http://hdl.handle.net/10197/9577
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Additive manufacturing: scientific and technological challenges, market uptake and opportunities
(2018)
Tofail, Syed A.M.; Koumoulos, Elias P.; Bandyopadhyay, Amit; Bose, Susmita; O'Dono...
Additive manufacturing: scientific and technological challenges, market uptake and opportunities
(2018)
Tofail, Syed A.M.; Koumoulos, Elias P.; Bandyopadhyay, Amit; Bose, Susmita; O'Donoghue, Lisa M.T.; Charitidis, Costas A.
Abstract:
Additive manufacturing (AM) is fundamentally different from traditional formative or subtractive manufacturing in that it is the closest to the ‘bottom up’ manufacturing where a structure can be built into its designed shape using a ‘layer-by-layer’ approach rather than casting or forming by technologies such as forging or machining. AM is versatile, flexible, highly customizable and, as such, can suite most sectors of industrial production. Materials to make these parts/objects can be of a widely varying type. These include metallic, ceramic and polymeric materials along with combinations in the form of composites, hybrid, or functionally graded materials (FGMs). The challenge remains, however, to transfer this ‘making’ shapes and structures into obtaining objects that are functional. A great deal of work is needed in AM in addressing the challenges related to its two key enabling technologies namely ‘materials’ and ‘metrology’ to achieve this functionality in a predictive and repr...
http://hdl.handle.net/10344/7198
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Biosensors—recent advances and future challenges in electrode materials
(2020)
Otero, Fernando; Magner, Edmond
Biosensors—recent advances and future challenges in electrode materials
(2020)
Otero, Fernando; Magner, Edmond
Abstract:
Electrochemical biosensors benefit from the simplicity, sensitivity, and rapid response of electroanalytical devices coupled with the selectivity of biorecognition molecules. The implementation of electrochemical biosensors in a clinical analysis can provide a sensitive and rapid response for the analysis of biomarkers, with the most successful being glucose sensors for diabetes patients. This review summarizes recent work on the use of structured materials such as nanoporous metals, graphene, carbon nanotubes, and ordered mesoporous carbon for biosensing applications. We also describe the use of additive manufacturing (AM) and review recent progress and challenges for the use of AM in biosensing applications.
http://hdl.handle.net/10344/8977
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Constitutive modeling of additive manufactured Ti-6Al-4V cyclic elastoplastic behaviour
(2016)
Kourousis, Kyriakos I.; Agius, Dylan J.; Wang, Chun H.; Subic, Aleksandar
Constitutive modeling of additive manufactured Ti-6Al-4V cyclic elastoplastic behaviour
(2016)
Kourousis, Kyriakos I.; Agius, Dylan J.; Wang, Chun H.; Subic, Aleksandar
Abstract:
Metal additive manufacturing techniques have been increasingly attracting the interest of the aerospace and biomedical industry. A particular focus has been on high value and complexity parts and components, as there the advantages offered by additive manufacturing are very significant for the design and production organisations. Various additive manufacturing techniques have been tested and utilized over the past years, with laser-based technology being among the preferred solutions – e.g. selective laser melting / sintering (SLM / SLS). Fatigue qualification, as one of the primary design challenges to meet, imposes the need for extensive material testing. Moreover, this need is amplified by the fact that currently there is very limited in-service experience and understanding of the distinct mechanical behaviour of additively manufactured metallic materials. To this end, material modelling can serve as a mediator, nevertheless research particular to additively manufactured metals i...
http://hdl.handle.net/10344/5294
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Cross entropy weight minimization of a compressive strut
(2018)
O'Brien, Eugene J.; Malekjafarian, Abdollah; Micu, Alexandra
Cross entropy weight minimization of a compressive strut
(2018)
O'Brien, Eugene J.; Malekjafarian, Abdollah; Micu, Alexandra
Abstract:
2nd International Conference on Progress in Additive Manufacturing (Pro-AM 2016), Singapore, May, 2016
In this study, a population-based optimization algorithm is used to minimize the weight of a compressive strut. A geometrically nonlinear analysis is carried out to get an accurate measure of the structure's true capacity, allowing for individual member and overall structure (and sub-structure) buckling. To overcome the computational challenge of nonlinear analysis, the study uses a simple definition of the onset of instability and hence the number of iterations is cut to a minimum.
Science Foundation Ireland
Enterprise Ireland
http://hdl.handle.net/10197/9245
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Cyclic plasticity of the as-built EOS maraging steel: preliminary experimental and computational results
(2020)
Mooney, Barry; Agius, Dylan J.; Kourousis, Kyriakos I.
Cyclic plasticity of the as-built EOS maraging steel: preliminary experimental and computational results
(2020)
Mooney, Barry; Agius, Dylan J.; Kourousis, Kyriakos I.
Abstract:
This short communication offers a preliminary view on ongoing research conducted on the as-built EOS maraging steel 300. The material’s cyclic elastoplastic characteristics under strain-controlled loading have been investigated experimentally. Specimens fabricated under two primary orientations, horizontally and vertically to the build plate, have been tested. The obtained stress–strain hysteresis loops exhibited symmetry, with the vertical specimen showing a higher plastic strain energy dissipation capability than the horizontal specimen. Modelling of the material’s elastoplastic behaviour was performed with a commonly used kinematic hardening rule, combined with both isotropic and anisotropic yield functions and elasticity moduli. The obtained simulations of the hysteresis loops, from the implementation of these two plasticity models, indicate the advantage of the anisotropic modelling approach over the isotropic approach. The anisotropic plasticity model describes in a more repre...
http://hdl.handle.net/10344/8626
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Design of a Kelvin cell acoustic metamaterial
(2020)
Kennedy, John; Rice, Henry; Trimble, Daniel; G?ransson, Peter; Dowling, Luke
Design of a Kelvin cell acoustic metamaterial
(2020)
Kennedy, John; Rice, Henry; Trimble, Daniel; G?ransson, Peter; Dowling, Luke
Abstract:
Advancements in 3D print technology now allow the printing of structured acoustic absorptive materials at appropriate microscopic scales and sample sizes. Optimisation of parameter sets associated with a Kelvin Cell structure have the potential to develop various metabehaviours in the associated acoustic responses. The repeatability of the fundamental cell unit also provide a route for the development of viable macro models to simulate built up structures based on detailed models of the individual cell units. This paper describes a process to model, print and test such a sample. Manufacturing restraints will initially guide the optimised design and introduce response uncertainties associated with surface finishes and critical geometric dimensions. A ?micro to macro? model is developed using a full visco thermal acoustic model of a single cell to develop a frequency dependent cell transfer matrix. The transfer matrices for the repeated cells may then be combined until sufficient mate...
http://hdl.handle.net/2262/92757
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Effects of Laser Power on Geometry, Microstructure and Mechanical Properties of Printed Ti-6Al-4V Parts
(2021)
Rossi Kaschel, Frederico; Celikin, Mert; Dowling, Denis P.
Effects of Laser Power on Geometry, Microstructure and Mechanical Properties of Printed Ti-6Al-4V Parts
(2021)
Rossi Kaschel, Frederico; Celikin, Mert; Dowling, Denis P.
Abstract:
This study investigated the effect of laser power on the properties of Ti-6Al-4V alloy parts produced by additive manufacturing. The printing study was carried out using the laser beam powder bed fusion (PBF-LB) technique (Renishaw RenAM 500M). The laser power was altered in the range of 100–400 W, in order to evaluate the effects of changing the input energy received by the powder particles on the as-built parts. The impact of changing laser power was investigated based on printed part dimensions, porosity, morphology, micro/nanostructure, wear, hardness and tensile properties. It was determined that laser power has a direct influence on part dimensional accuracy, with larger dimensions compared with CAD design under the processing conditions used, obtained at higher powers i.e. 2 % at 250 W, while 4 % at 400 W. The border thickness for rounded edges was found to be ∼0.2 ± 0.06 mm greater than that obtained for straight edges, printed on the same quarter circle samples. A more homo...
http://hdl.handle.net/10197/11944
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Enhancing the bearing strength of woven carbon fibre thermoplastic composites through additive manufacturing
(2020)
Dickson, Andrew N.; Dowling, Denis P.
Enhancing the bearing strength of woven carbon fibre thermoplastic composites through additive manufacturing
(2020)
Dickson, Andrew N.; Dowling, Denis P.
Abstract:
This paper examines a novel additive manufacturing (AM) technique for the fabrication of woven multilaminate composites. The printing studies were carried out using nylon coated carbon fibre Tow in the form of a filament. This pathing technique allows for a woven structure to be integrated with features (such as notches) previously only possible through destructive machining processes. In order to evaluate the performance of these printed composites, bearing response studies were carried out. 6 mm holes were routed into a multilaminate woven composite structure, the resulting part’s mechanical performance was then tested and compared with specimens which had been drilled post printing. Specimen were comprised of 9 woven laminates stacked to form a 3.1 mm thick standardised test coupon for single and double shear testing (ASTM D5961). Current industry standard machining techniques result in fibre discontinuity and damage, this results in suboptimal mechanical performance of composite...
http://hdl.handle.net/10197/11731
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Evaluation of cartilage repair by mesenchymal stem cells seeded on a PEOT/PBT scaffold in an osteochondral defect
(2016)
Barron, Valerie; Merghani, Khalid; Shaw, Georgina; Coleman, Cynthia; Hayes, Jessica; An...
Evaluation of cartilage repair by mesenchymal stem cells seeded on a PEOT/PBT scaffold in an osteochondral defect
(2016)
Barron, Valerie; Merghani, Khalid; Shaw, Georgina; Coleman, Cynthia; Hayes, Jessica; Ansboro, Sharon; Manian, Abi; O'Malley, Grace; Connolly, Emma; Nandakumar, Ananda; Van Blitterswijk, Clemen; Habibovic, Pamela; Moroni, Lorenzo; Shannon, Fintan; Barry, Frank; Murphy, Mary
Abstract:
The main objective of this study was to evaluate the effectiveness of a mesenchymal stem cell (MSC)-seeded polyethylene-oxide-terephthalate/polybutylene-terephthalate (PEOT/PBT) scaffold for cartilage tissue repair in an osteochondral defect using a rabbit model. Material characterisation using scanning electron microscopy indicated that the scaffold had a 3D architecture characteristic of the additive manufacturing fabrication method, with a strut diameter of 296 +/- A 52 mu m and a pore size of 512 +/- A 22 mu m x 476 +/- A 25 mu m x 180 +/- A 30 mu m. In vitro optimisation revealed that the scaffold did not generate an adverse cell response, optimal cell loading conditions were achieved using 50 mu g/ml fibronectin and a cell seeding density of 25 x 10(6) cells/ml and glycosaminoglycan (GAG) accumulation after 28 days culture in the presence of TGF beta 3 indicated positive chondrogenesis. Cell-seeded scaffolds were implanted in osteochondral defects for 12 weeks, with cell-free ...
http://hdl.handle.net/10379/5868
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Evolution of 3D printing methods and materials for electrochemical energy storage
(2020)
Egorov, Vladimir; Gulzar, Umair; Zhang, Yan; Breen, Siobhán; O'Dwyer, Colm
Evolution of 3D printing methods and materials for electrochemical energy storage
(2020)
Egorov, Vladimir; Gulzar, Umair; Zhang, Yan; Breen, Siobhán; O'Dwyer, Colm
Abstract:
Additive manufacturing has revolutionized the building of materials, and 3D-printing has become a useful tool for complex electrode assembly for batteries and supercapacitors. The field initially grew from extrusion-based methods and quickly evolved to photopolymerization printing, while supercapacitor technologies less sensitive to solvents more often involved material jetting processes. The need to develop higher-resolution multimaterial printers is borne out in the performance data of recent 3D printed electrochemical energy storage devices. Underpinning every part of a 3D-printable battery are the printing method and the feed material. These influence material purity, printing fidelity, accuracy, complexity, and the ability to form conductive, ceramic, or solvent-stable materials. The future of 3D-printable batteries and electrochemical energy storage devices is reliant on materials and printing methods that are co-operatively informed by device design. Herein, the material and ...
http://hdl.handle.net/10468/10363
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I-nteract: A Cyber-Physical System for Real-Time Interaction With Physical and Virtual Objects Using Mixed Reality Technologies for Additive Manufacturing
(2021)
Malik, Ammar; Lhachemi, Hugo; Shorten, Robert
I-nteract: A Cyber-Physical System for Real-Time Interaction With Physical and Virtual Objects Using Mixed Reality Technologies for Additive Manufacturing
(2021)
Malik, Ammar; Lhachemi, Hugo; Shorten, Robert
Abstract:
This paper presents I-nteract, a cyber-physical system that enables real-time interaction with real and virtual objects in a mixed reality environment to design 3D models for additive manufacturing. The system has been developed using mixed reality technologies such as HoloLens, for augmenting visual feedback, and haptic gloves, for augmenting haptic force feedback. The efficacy of the system has been demonstrated by generating a 3D model using a novel scanning method to 3D print a customized orthopedic cast for human arm, by estimating spring rates of compression springs, and by simulating interaction with a virtual spring in a mixed reality environment.
European Commission - European Regional Development Fund
Science Foundation Ireland
I-Form Industry Partners
http://hdl.handle.net/10197/11964
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Liquid-phase 3D bioprinting of gelatin alginate hydrogels: influence of printing parameters on hydrogel line width and layer height
(2019)
Alruwaili, Maha; Lopez, Jose A.; McCarthy, Kevin; Reynaud, Emmanuel G.; Rodriguez, Bria...
Liquid-phase 3D bioprinting of gelatin alginate hydrogels: influence of printing parameters on hydrogel line width and layer height
(2019)
Alruwaili, Maha; Lopez, Jose A.; McCarthy, Kevin; Reynaud, Emmanuel G.; Rodriguez, Brian J.
Abstract:
Extrusion-based 3D bioprinting is a direct deposition approach used to create three-dimensional (3D) tissue scaffolds typically comprising hydrogels. Hydrogels are hydrated polymer networks that are chemically or physically cross-linked. Often, 3D bioprinting is performed in air, despite the hydrated nature of hydrogels and the potential advantage of using a liquid phase to provide cross-linking and otherwise functionalize the hydrogel. In this work, we print gelatin alginate hydrogels directly into a cross-linking solution of calcium chloride and investigate the influence of nozzle diameter, distance between nozzle and surface, calcium chloride concentration, and extrusion rate on the dimensions of the printed hydrogel. The hydrogel layer height was generally found to increase with increasing extrusion rate and nozzle distance, according to the increased volume extruded and the available space, respectively. In addition, the hydrogel width was generally found to increase with decre...
http://hdl.handle.net/10197/10925
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Low temperature fused deposition modeling (FDM) 3D printing of thermolabile drugs
(2018)
Kollamaram, Gayathri; Croker, Denise M.; Walker, Gavin M.; Goyanes, Alvaro; Basit, Abdu...
Low temperature fused deposition modeling (FDM) 3D printing of thermolabile drugs
(2018)
Kollamaram, Gayathri; Croker, Denise M.; Walker, Gavin M.; Goyanes, Alvaro; Basit, Abdul W.; Gaisford, Simon
Abstract:
Fused deposition modelling (FDM) is the most commonly investigated 3D printing technology for the manufacture of personalized medicines, however, the high temperatures used in the process limit its wider application. The objective of this study was to print low-melting and thermolabile drugs by reducing the FDM printing temperature. Two immediate release polymers, Kollidon VA64 and Kollidon 12PF were investigated as potential candidates for low-temperature FDM printing. Ramipril was used as the model low melting temperature drug (109 °C); to the authors’ knowledge this is the lowest melting point drug investigated to date by FDM printing. Filaments loaded with 3% drug were obtained by hot melt extrusion at 70 °C and ramipril printlets with a dose equivalent of 8.8 mg were printed at 90 °C. HPLC analysis confirmed that the drug was stable with no signs of degradation and dissolution studies revealed that drug release from the printlets reached 100% within 20–30 min. Variable temperat...
http://hdl.handle.net/10344/6837
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Mechanism of Stress Relaxation and Phase Transformation in Additively Manufactured Ti-6Al-4V via in situ High Temperature XRD and TEM Analyses
(2021)
Rossi Kaschel, Frederico; Vijayaraghavan, R. K.; Shmeliov, A.; Dowling, Denis P.; Celik...
Mechanism of Stress Relaxation and Phase Transformation in Additively Manufactured Ti-6Al-4V via in situ High Temperature XRD and TEM Analyses
(2021)
Rossi Kaschel, Frederico; Vijayaraghavan, R. K.; Shmeliov, A.; Dowling, Denis P.; Celikin, Mert; et al.
Abstract:
Additive manufacturing is being increasingly used in the fabrication of Ti-6Al-4V parts to combine excellentmechanical properties and biocompatibility with high precision. Unfortunately, due to the build-up of ther-mal residual stresses and the formation of martensitic structure across a wide range of typical processingconditions, it is generally necessary to use a post-thermal treatment to achieve superior mechanical perfor-mance. This investigation aims to obtain a deeper understanding of the micro/nanostructural evolution(a0martensite phase decomposition), accounting for the kinetics of phase transformation during the heattreatment of 3D-printed Ti-6Al-4V alloy. As the mechanism of phase transformation and stress relaxation isstill ambiguous, in this study the changes in crystal lattice, phase, composition and lattice strain were investi-gated up to 1000°C using bothin situhigh temperature X-ray diffraction (XRD) and transmission electronmicroscopy (TEM). Based on the result a me...
http://hdl.handle.net/10197/11945
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Mitigation and control of the overcuring effect in mask projection micro-stereolithography
(2017)
O'Neill, Paul F.; Kent, Nigel J.; Brabazon, Dermot
Mitigation and control of the overcuring effect in mask projection micro-stereolithography
(2017)
O'Neill, Paul F.; Kent, Nigel J.; Brabazon, Dermot
Abstract:
Mask Projection micro-Stereolithography (MPμSL) is an additive manufacturing technique capable of producing solid parts with micron-scale resolution from a vat of photocurable liquid polymer resin. Although the physical mechanism remains the same, the process differs from traditional laser-galvanometer based stereolithography (SL) in its use of a dynamic mask UV projector, or digital light processor (DLP), which cures each location within each 3D layer at the same time. One area where MPµSL has garnered considerable attention is in the field of microfluidics and Lab-on-a-Chip, where complex multistep microfabrication techniques adopted from the semiconductor industry are still widely used, and where MPµSL offers the ability to fabricate completely encapsulated fluidic channels in a single step and at low cost [1–3]. However, a significant obstacle exists in the prevention of channel blockage due to overcuring of the polymer resin [4, 5]. Overcuring can be attributed to the so-called...
http://doras.dcu.ie/22081/
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Planar semiconductor membranes with brightness enhanced embedded quantum dots via electron beam induced deposition of 3D nanostructures: Implications for solid state lighting
(2020)
Varo, Simone; Li, Xin; Juska, Gediminas; Ranjbar Jahromi, Iman; Gocalinska, Agnieszka M...
Planar semiconductor membranes with brightness enhanced embedded quantum dots via electron beam induced deposition of 3D nanostructures: Implications for solid state lighting
(2020)
Varo, Simone; Li, Xin; Juska, Gediminas; Ranjbar Jahromi, Iman; Gocalinska, Agnieszka M.; Di Falco, Andrea; Pelucchi, Emanuele
Abstract:
The engineering of the surrounding photonic environment is one of the most successful approaches routinely used to increase light extraction efficiency and tune the properties of solid state sources of quantum light. However, results achieved so far have been hampered by the lack of a technology that allows for the straightforward fabrication of large-scale 3D nano- and micro- features, with very high resolution and sufficient flexibility in terms of available materials. In this paper we show that electron beam induced deposition can be a very promising approach to solve this issue, as exemplified by the fabrication of Pt and SiO2 nanofeatures on a membrane containing ordered arrays of site-controlled pyramidal quantum dots. Micro-photoluminescence has been used to compare the emission of the dots before and after the deposition of the structures, remarkably showing both a significant increase in the light extraction efficiency and no degradation of the spectral quality, implying th...
http://hdl.handle.net/10468/10955
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Plastic anisotropy of additively manufactured maraging steel: influence of the build orientation and heat treatments
(2019)
Mooney, Barry; Kourousis, Kyriakos I.; Raghavendra, Ramesh
Plastic anisotropy of additively manufactured maraging steel: influence of the build orientation and heat treatments
(2019)
Mooney, Barry; Kourousis, Kyriakos I.; Raghavendra, Ramesh
Abstract:
This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) system. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However...
http://hdl.handle.net/10344/7510
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Prediction of microstructure evolution for additive manufacturing of Ti-6Al-4V
(2020)
Yang, Xinyu; Barrett, Richard A.; Tong, Mingming; Harrison, Noel M.; Leen, Sean B.
Prediction of microstructure evolution for additive manufacturing of Ti-6Al-4V
(2020)
Yang, Xinyu; Barrett, Richard A.; Tong, Mingming; Harrison, Noel M.; Leen, Sean B.
Abstract:
A key challenge for successful exploitation of additive manufacturing (AM) across a broad range of industries is the development of fundamental understanding of the relationships between process control and mechanical performance of manufactured components. The present work is focused on the development of predictive methods for process-structure-property control of AM. In particular, laser beam powder bed fusion (PBF-LB) is identified as a key process for manufacture of metallic AM components. Ti-6Al-4V alloy is an important metal alloy for numerous high-performance applications, including the biomedical and aerospace industries. This paper presents initial developments on a model for microstructure prediction in PBF-LB manufacturing of Ti-6Al-4V, primarily focused on solid-state phase transformation and dislocation density evolution. The motivation is to quantify microstructure variables which control mechanical behavior, including tensile strength and ductility. A finite element ...
http://hdl.handle.net/10379/16146
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Process phenomena influencing the tensile and anisotropic characteristics of additively manufactured maraging steel
(2019)
Mooney, Barry; Kourousis, Kyriakos I.; Raghavendra, Ramesh; Agius, Dylan J.
Process phenomena influencing the tensile and anisotropic characteristics of additively manufactured maraging steel
(2019)
Mooney, Barry; Kourousis, Kyriakos I.; Raghavendra, Ramesh; Agius, Dylan J.
Abstract:
The tensile mechanical properties and anisotropy levels of identical test-coupons, fabricated from maraging steel 300 (MS300) using two alternative EOS EOSINT M280 Additive Manufacturing (AM) systems, have been examined. The mechanical performance variations resulting from process differences between the two suppliers and the part's build volume orientation (0°, 45°, and 90°) are investigated. Significant microstructural discrepancies, affecting mechanical performance, plasticity and anisotropy levels, have been observed in the as-built samples obtained from the two suppliers. A difference in the angle of the laser scan strategy, in conjunction with unfavourable powder feedstock characteristics, are understood to have had a profound influence on the plasticity and anisotropy divergences observed in the AM MS300 alloy. Plastic anisotropy levels can be largely reduced through application of aging heat-treatments, however, a degree of transverse strain anisotropy is likely to rema...
http://hdl.handle.net/10344/7509
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