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Article
Publication date: 19 January 2015

Jason B. Jones, David I. Wimpenny and Greg J Gibbons

This paper aims to investigate the effects on material properties of layer-by-layer application of pressure during fabrication of polymeric parts by additive manufacturing (AM)…

1662

Abstract

Purpose

This paper aims to investigate the effects on material properties of layer-by-layer application of pressure during fabrication of polymeric parts by additive manufacturing (AM). Although AM, also known popularly as 3D printing, has set a new standard for ease of use and minimal restraint on geometric complexity, the mechanical part properties do not generally compare with conventional manufacturing processes. Contrary to other types of polymer processing, AM systems do not normally use (in-process) pressure during part consolidation.

Design/methodology/approach

Tensile specimens were produced in Somos 201 using conventional laser sintering (LS) and selective laser printing (SLP) – a process under development in the UK, which incorporates the use of pressure to assist layer consolidation.

Findings

Mechanical testing demonstrated the potential to additively manufacture parts with significantly improved microstructure and mechanical properties which match or exceed conventional processing. For example, the average elongation at break and ultimate tensile strength of a conventionally laser-sintered thermoplastic elastomer (Somos 201) increased from 136 ± 28 per cent and 4.9 ± 0.4 MPa, to 513 ± 35 per cent and 10.4 ± 0.4 MPa, respectively, when each layer was fused with in-process application of pressure (126 ± 9 kPa) by SLP.

Research limitations/implications

These results are based on relatively small sample size, but despite this, the trends observed are of significant importance to the elimination of voids and porosity in polymeric parts.

Practical implications

Layerwise application of pressure should be investigated further for defect elimination in AM.

Originality/value

This is the first study on the effects of layerwise application of pressure in combination with area-wide fusing.

Details

Rapid Prototyping Journal, vol. 21 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 19 April 2013

Andrew Johnson, Guy A. Bingham and David I. Wimpenny

The purpose of this paper is to ascertain the stab resistance characteristics of a series of planar and articulated laser sintered (LS) samples, in accordance with the United…

1464

Abstract

Purpose

The purpose of this paper is to ascertain the stab resistance characteristics of a series of planar and articulated laser sintered (LS) samples, in accordance with the United Kingdom Home Office Scientific Development Branch (HOSDB) Body Armour Standard – Publication 39/07.

Design/methodology/approach

A series of LS planar samples were manufactured using an EOS P100 Formiga system, manufactured from 100 per cent virgin or a 50:50 mix of recycled and virgin Nylon (PA2200), ranging in thickness from 1‐10 mm. All planar samples were stab tested to the HOSDB knife‐resistance (KR) level one impact energy of 24 Joules, using an in‐house manufactured HOSDB guided rail drop test impact rig and standardised knives. Penetration through the underside of each sample was measured and recorded. These results were then used to develop an articulated, additive manufactured (AM) scale textile – LS from a 50:50 mix of recycled and virgin PA2200 powder. These samples were then tested using the aforementioned impact rig and stab impact energy.

Findings

The research demonstrated that while virgin PA2200 sample required a minimum thickness of 8 mm to achieve stab‐resistance below the HOSDB maximum penetration limit of 7 mm, this figure can be reduced to 5.6 mm when manufacturing LS planar samples from a 50:50 mix of virgin and recycled PA2200. Results from stab testing the articulated samples indicated a successful AM textile‐like design, with a maximum knife penetration of 1.6 mm – below the 7 mm HOSDB limit.

Originality/value

The paper describes a unique application of AM technologies for the manufacture of high‐performance stab resistant AM textiles.

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Article
Publication date: 14 October 2020

Aldi Mehmeti, Pavel Penchev, Donal Lynch, Denis Vincent, Nathalie Maillol, Johannes Maurath, Julien Bajolet, David Ian Wimpenny, Khamis Essa and Stefan Dimov

The paper reports an investigation into the mechanical behaviour of hybrid components produced by combining the capabilities of metal injection moulding (MIM) with the laser-based…

259

Abstract

Purpose

The paper reports an investigation into the mechanical behaviour of hybrid components produced by combining the capabilities of metal injection moulding (MIM) with the laser-based powder bed fusion (PBF) process to produce small series of hybrid components. The research investigates systematically the mechanical properties and the performance of the MIM/PBF interfaces in such hybrid components.

Design/methodology/approach

The MIM process is employed to fabricate relatively lower cost preforms in higher quantities, whereas the PBF technology is deployed to build on them sections that can be personalised, customised or functionalised to meet specific technical requirements.

Findings

The results are discussed, and conclusions are made about the mechanical performance of such hybrid components produced in batches and also about the production efficiency of the investigated hybrid manufacturing (HM) route. The obtained results show that the proposed HM route can produce hybrid MIM/PBF components with consistent mechanical properties and interface performance which comply with the American Society for Testing and Materials (ASTM) standards.

Originality/value

The manufacturing of hybrid components, especially by combining the capabilities of additive manufacturing processes with cost-effective complementary technologies, is designed to be exploited by industry because they can offer flexibility and cost advantages in producing small series of customisable products. The findings of this research will contribute to further develop the state of the art in regards to the manufacturing and optimisation of hybrid components.

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Article
Publication date: 1 October 2000

David Ian Wimpenny and Gregory John Gibbons

This work was performed within IMI Spray Mould, an EPSRC joint funded programme, aimed at developing a manufacturing route for large aerospace composite forming tooling, based on…

1004

Abstract

This work was performed within IMI Spray Mould, an EPSRC joint funded programme, aimed at developing a manufacturing route for large aerospace composite forming tooling, based on metal spray technologies. Assesses the mechanical properties of Invar steel coatings, deposited using electric arc spraying, and correlates these properties to the spray parameters and processes used so as to offer coatings with characteristics appropriate to the tooling requirements. In particular, two processing methods, inert and air atomisation, and three arc spray gun configurations (air cap design) are evaluated. The mechanical properties of the coatings are found to be low compared to bulk Invar, regardless of the spray parameters and hardware used. Inert arc spraying affords more consistent coating characteristics but this comes with a compromised durability. The spray hardware is found to be more significant in determining the coating properties than the parameters employed.

Details

Aircraft Engineering and Aerospace Technology, vol. 72 no. 5
Type: Research Article
ISSN: 0002-2667

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Publication date: 19 July 2022

C. C. Wolhuter and L. Jacobs

The aim of this chapter is to investigate the potential of the disruption brought about by the COVID-19 pandemic to break the stagnation in the field of comparative and

Abstract

The aim of this chapter is to investigate the potential of the disruption brought about by the COVID-19 pandemic to break the stagnation in the field of comparative and international education, detected on many fronts of the field by various scholars in the field. The chapter commences with a survey of the historical evolution of the field of comparative and international education, showing how the field has historically come to be defined by contextually induced discourse. At the same time, the historically trodden furrows have resulted in the field becoming trapped by historical forces, resulting in some stagnation in the field. It is argued that impediments to progress in the field of comparative and international education are the severance from practice, the “black box” syndrome of paying more attention to the societal context than to education, the tenacious attachment to the nation-state as the sole geographic level of analysis, the lack of an autochthonous theory, persistent Northern hegemony, and the regression of space and infrastructure at universities. Thereafter, the outbreak of the COVID-19 pandemic and the impact thereof on education are discussed. In conclusion, the potential of the disruption brought about by the pandemic for the revisitation of comparative and international education is assessed.

Details

Annual Review of Comparative and International Education 2021
Type: Book
ISBN: 978-1-80382-618-9

Keywords

Available. Open Access. Open Access
Article
Publication date: 15 June 2021

David M. Herold, Katarzyna Nowicka, Aneta Pluta-Zaremba and Sebastian Kummer

The purpose of this paper is to provide new insights into the reactions and lessons learned with regard to the COVID-19 pandemic in terms of how logistics service providers (LSPs…

13926

Abstract

Purpose

The purpose of this paper is to provide new insights into the reactions and lessons learned with regard to the COVID-19 pandemic in terms of how logistics service providers (LSPs) managed to maintain supply chains resilience and what focus areas have been changed to keep operations functional and uphold financial stability.

Design/methodology/approach

Based on data-gathering techniques in interpretive research this study collected primary data via semi-structured interviews, interviewing informants from selected LSPs that operate on a global scale.

Findings

The results show that LSPs have built their reactions and actions to the COVID-19 outbreak around five main themes: “create revenue streams,” “enhance operational transport flexibility,” “enforce digitalization and data management,” “optimize logistics infrastructure” and “optimize personnel capacity.” These pillars build the foundation to LSP resilience that enables supply chains to stay resilient during an external shock of high impact and low probability.

Originality/value

The results of this study provide insights into how LSPs have managed the downsides and found innovative ways to overcome operational and financial challenges during the COVID-19 outbreak. As one of the first studies that specially focuses on the role of LSPs during the COVID-19 pandemic, this study categorizes the LSPs’ reactions and provides a “lessons learned” framework from a managerial perspective. From a theoretical perspective, this paper discusses the strategic role of LSPs in supply chain management and thereby extends current supply chain literature with a focus on LSP resilience.

Details

Supply Chain Management: An International Journal, vol. 26 no. 6
Type: Research Article
ISSN: 1359-8546

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Article
Publication date: 1 October 1954

B.R. Noton

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display…

66

Abstract

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.

Details

Aircraft Engineering and Aerospace Technology, vol. 26 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 27 January 2021

Irina Tatiana Garces and Cagri Ayranci

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the…

1142

Abstract

Purpose

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities.

Design/methodology/approach

This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted.

Findings

This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures.

Originality/value

Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.

Details

Rapid Prototyping Journal, vol. 27 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 March 2002

Brian Rooks

A seminar organised by the Rapid Prototype and Manufacturing Association (RPMA) held at the UK Castings Development Centre in Birmingham presented a series of case studies on the…

1584

Abstract

A seminar organised by the Rapid Prototype and Manufacturing Association (RPMA) held at the UK Castings Development Centre in Birmingham presented a series of case studies on the application of rapid prototyping methods in the manufacture casting tools. Methods described included stereolithography, laser sintering and sand cast moulding. Amongst the case studies were descriptions of the production of a novel A‐post for the Volvo Safety Concept car, the production and ranking for accuracy and repeatability of aerospace components and the direct production of sand moulds for cylinder heads and a hydraulic valve.

Details

Assembly Automation, vol. 22 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

Available. Open Access. Open Access
Article
Publication date: 25 November 2020

Jasmin Mikl, David M. Herold, Marek Ćwiklicki and Sebastian Kummer

Digital freight forwarder (DFF) start-ups and their associated business models have gained increasing attention within both academia and industry. However, there is a lack of…

8613

Abstract

Purpose

Digital freight forwarder (DFF) start-ups and their associated business models have gained increasing attention within both academia and industry. However, there is a lack of empirical research investigating the differences between DFFs and traditional freight forwarders (TFF) and the impact of digital start-ups on incumbents' companies. In response, this study aims to examine the key business model characteristics that determine DFFs and TFFs and propose a framework illustrating the extent to which digital logistics start-ups influence incumbent logistics companies.

Design/methodology/approach

Based on the primary data gathered from eight interviews with experts from start-ups' and incumbents' logistics companies, as well as secondary data, the authors identify the main factors of DFFs start-ups that have an impact on TFFs and analyze the similarities and differences in regard to the business model components' value proposition, value creation, value delivery and value capture.

Findings

The results show that differences between DFFs and TFFs appear in all four business models' components: value proposition, value creation, value delivery and value capture. In particular, the authors identify three main factors that need to be considered when assessing the impact of DFFs on TFFs: (1) the company size, (2) the market cultivation strategy and (3) the transport mode.

Originality/value

This is one of the first studies to specifically examine the key business model differences between DFFs and TFFs and to propose a conceptual framework for understanding the impact of digital logistics start-ups on incumbent companies.

Details

The International Journal of Logistics Management, vol. 32 no. 4
Type: Research Article
ISSN: 0957-4093

Keywords

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