Andrew Triantaphyllou

Manufacturing Technology Centre (United Kingdom)

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L.E.J. Thomas-Seale

University of Birmingham

Yijun Liu

Chinese Academy of Tropical Agricultural Sciences

Malcolm D. Glendenning

Glass Technology Services

Rosemary Dyson

University of Birmingham

Barnaby Hawthorn

University of Birmingham

Muhammad Farhan Khan

Quaid-i-Azam University

Shukri Afazov

Nottingham Trent University

Richard Leach

University of Nottingham

Liam Bradley-Smith

Manufacturing Technology Centre (United Kingdom)

Jackson Kirkman‐Brown

Birmingham Women’s and Children’s NHS Foundation Trust

Cooperative Institutions

Manufacturing Technology Centre (United Kingdom)

Coventry (United Kingdom)

University of Birmingham

University of Nottingham

Glass Technology Services

University of Sheffield

Nottingham Trent University

National Physical Laboratory

Engineering and Physical Sciences Research Council

Imperial College London

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Multiscale Design for the Additive Manufacture of Medical Devices

L.E.J. Thomas-Seale S. Kanagalingam D. Shaw Andrew Triantaphyllou Khamis Essa

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Metal|glass Interface Characterisation Of A Multiscale Bioactive Surface Structure On Ti-6Al-4V Alloy With Laser DED Process

Yijun Liu Andrew Triantaphyllou David A. Eustice Robert Ireson Chris Holcroft

The present study demonstrates the feasibility to fabricate a multiscale bioactive surface structure onto a biomedical grade Ti-6Al-4V alloy substrate using a multi-material blown powder laser Direct Energy Deposition process (DED). The multiscale surface structure consisted of two layers: a Ti-6Al-4V transition layer with a customised structure, deposited onto a Ti-6Al-4V alloy substrate, followed by a layer of customised bioactive glass cladded on top. It is possible to create a transition layer with physical interlocking features that are fully bonded with the bioactive glass for enhancement of the metal-glass adhesion. The metal|glass interface was characterised in terms of metallurgical reactions and mechanical properties. Indentation tests confirmed excellent cohesion of the metal-glass interface. The microhardness of the bioactive glass near the interface varied from 5.44 to 7.78 GPa. Fracture toughness of the cladded glass was estimated in the range of 1.40-3.91 MPa m1|2.

Interface (matter)

Titanium alloy

10.59499/wp225370564

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Surface texture measurement for additive manufacturing

Surface Topography Metrology and Properties (2015)

Andrew Triantaphyllou Claudiu Giusca Gavin MacAulay Felix Roerig Matthias Hoebel

The surface texture of additively manufactured metallic surfaces made by powder bed methods is affected by a number of factors, including the powder's particle size distribution, the effect of the heat source, the thickness of the printed layers, the angle of the surface relative to the horizontal build bed and the effect of any post processing/finishing. The aim of the research reported here is to understand the way these surfaces should be measured in order to characterise them. In published research to date, the surface texture is generally reported as an Ra value, measured across the lay. The appropriateness of this method for such surfaces is investigated here. A preliminary investigation was carried out on two additive manufacturing processes—selective laser melting (SLM) and electron beam melting (EBM)—focusing on the effect of build angle and post processing. The surfaces were measured using both tactile and optical methods and a range of profile and areal parameters were reported. Test coupons were manufactured at four angles relative to the horizontal plane of the powder bed using both SLM and EBM. The effect of lay—caused by the layered nature of the manufacturing process—was investigated, as was the required sample area for optical measurements. The surfaces were also measured before and after grit blasting.

Texture (cosmology)

10.1088/2051-672x/3/2/024002

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Citations (236)

On the design workflow of auxetic metamaterials for structural applications

Smart Materials and Structures (2021)

Matthew Wallbanks Muhammad Farhan Khan Mahdi Bodaghi Andrew Triantaphyllou Ahmad Serjouei

Abstract Auxetic metamaterials exhibit an unexpected behaviour of a negative Poisson’s ratio (NPR), meaning they expand transversely when stretched longitudinally. This behaviour is generated predominantly due to the way individual elements of an auxetic lattice are structured. These structures are gaining interest in a wide variety of applications such as energy absorption, sensors, smart filters, vibration isolation and medical etc. Their potential could be further exploited by the use of additive manufacturing. Currently there is a lack of guidance on how to design these structures. This paper highlights state-of-the-art in auxetic metamaterials and its commonly used unit-cell types. It further explores the design approaches used in the literature on creating auxetic lattices for different applications and proposes, for the first time, a workflow comprising design, simulation and testing of auxetic structures. This workflow provides guidance on the design process for using auxetic metamaterials in structural applications.

Auxetics

10.1088/1361-665x/ac3f78

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Citations (48)

3D analysis of thermal and stress evolution during laser cladding of bioactive glass coatings

Journal of the mechanical behavior of biomedical materials/Journal of mechanical behavior of biomedical materials (2016)

Michał Krzyżanowski Szymon Bajda Yijun Liu Andrew Triantaphyllou W.M. Rainforth

Cladding (metalworking)

Thermal shock

Temperature Gradient

10.1016/j.jmbbm.2016.02.023

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Citations (59)

Tailoring surface roughness through the temporal variation of additive manufacturing process parameters

The International Journal of Advanced Manufacturing Technology (2024)

Barnaby Hawthorn Ailsa Mummery Nasim Mahmoodi Muhammad Farhan Khan Andrew Triantaphyllou

Abstract The benefits that additive manufacturing (AM) offers to the industry are generally well understood and appreciated. However, the current design for additive manufacturing (DfAM) methodologies and computer-aided manufacturing (CAM) packages neglect to exploit the full potential that AM can offer through its unique ability to vary material characteristics whilst the final component geometry is being formed. The purpose of this research is to demonstrate that additional design control can be gained through temporal DfAM (TDfAM). In this study, the ability to tailor the surface roughness of fused deposition modelling (FDM) AM polylactic acid (PLA) parts through the variation of two process parameters, nozzle temperature and print speed, is explored. The underpinning hypothesis is that variation of temperature and printing speed, can provide a significant change of surface roughness within one homogeneous part. This research demonstrated that nozzle temperature and print speed have a statistically significant effect on the surface roughness of the top and side surfaces. By increasing temperature and speed, the roughness of the side surfaces decreased and the roughness of the top surface increased. Furthermore, the in-silico implementation of TDfAM is demonstrated. As such, the research supports the hypothesis that TDfAM can enable additional control over the surface characteristics of a homogeneous part.

Fused Deposition Modeling

Deposition

10.1007/s00170-024-13532-9

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SIMULATING BIORESORBABLE LATTICE STRUCTURES TO ENABLE TIME-DEPENDENT STIFFNESS IN FRACTURE FIXATION DEVICES

Proceedings of the Design Society (2023)

Barnaby Hawthorn Andrew Triantaphyllou Farhan Khan Rosemary Dyson L.E.J. Thomas-Seale

Abstract Additive manufacture (AM) enables a greatly increased design freedom owing to its ability to manufacture otherwise difficult or impossible geometries. However, design creativity can often present itself as a barrier to realising the advantages that AM could offer. In this study the use of AM, bioresorbable materials and lattice design is considered as a method of satisfying contradicting design requirements during fracture healing. Often, immediately after a fracture high stiffness fixation is required; contradictingly during the remodelling phase high stiffness can inhibit bone healing. This study proposes the use of a bioresorbable body centred cubic (BCC) or face centred cubic (FCC) lattice structure to meet the need for tailored variation in implant stiffness over time. To reduce computational expense of lattice modelling a method is outlined, including the use of homogenisation. Results show homogenised representations perform within 5.2% and 1.4% for BCC and FCC unit cells respectively, with a 95% reduction in computational expense. Using resorption rates from the literature, time-dependent change in unit cell geometry was also modelled, showing the way in which a decrease in stiffness over time could be achieved.

Lattice (music)

10.1017/pds.2023.318

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Laser polishing of selective laser melted components

International Journal of Machine Tools and Manufacture (2015)

Sundar Marimuthu Andrew Triantaphyllou Mohammad Antar David Ian Wimpenny H. Earl Morton

Selective Laser Melting

10.1016/j.ijmachtools.2015.05.002

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Citations (246)

A methodology for precision additive manufacturing through compensation