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Article
Publication date: 3 February 2020

Feras Korkees, James Allenby and Peter Dorrington

3D printing of composites has a high degree of design freedom, which allows for the manufacture of complex shapes that cannot be achieved with conventional manufacturing…

Abstract

Purpose

3D printing of composites has a high degree of design freedom, which allows for the manufacture of complex shapes that cannot be achieved with conventional manufacturing processes. This paper aims to assess the design variables that might affect the mechanical properties of 3D-printed fibre-reinforced composites.

Design/methodology/approach

Markforged Mark-Two printers were used to manufacture samples using nylon 6 and carbon fibres. The effect of fibre volume fraction, fibre layer location and fibre orientation has been studied using three-point flexural testing.

Findings

The flexural strength and stiffness of the 3D-printed composites increased with increasing the fibre volume fraction. The flexural properties were altered by the position of the fibre layers. The highest strength and stiffness were observed with the reinforcement evenly distributed about the neutral axis of the sample. Moreover, unidirectional fibres provided the best flexural performance compared to the other orientations. 3D printed composites also showed various failure modes under bending loads.

Originality/value

Despite multiple studies available on 3D-printed composites, there does not seem to be a clear understanding and consensus on how the location of the fibre layers can affect the mechanical properties and printing versatility. Therefore, this study covered this design parameter and evaluated different locations in terms of mechanical properties and printing characteristics. This is to draw final conclusions on how 3D printing may be used to manufacture cost-effective, high-quality parts with excellent mechanical performance.

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Article
Publication date: 15 August 2019

Isaac Ferreira, Margarida Machado, Fernando Alves and António Torres Marques

In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless…

Abstract

Purpose

In industry, fused filament fabrication (FFF) offers flexibility and agility by promoting a reduction in costs and in the lead-time (i.e. time-to-market). Nevertheless, FFF parts exhibit some limitations such as lack of accuracy and/or lower mechanical performance. As a result, some alternatives have been developed to overcome some of these restrictions, namely, the formulation of high performance polymers, the creation of fibre-reinforced materials by FFF process and/or the design of new FFF-based technologies for printing composite materials. This work aims to analyze these technologies.

Design/methodology/approach

This work aims to study and understand the advances in the behaviour of 3D printed parts with enhanced performance by its reinforcement with several shapes and types of fibres from nanoparticles to continuous fibre roving. Thus, a comprehensive survey of significant research studies carried out regarding FFF of fibre-reinforced thermoplastics is provided, giving emphasis to the most relevant and innovative developments or adaptations undergone at hardware level and/or on the production process of the feedstock.

Findings

It is shown that the different types of reinforcement present different challenges for the printing process with different outcomes in the part performance.

Originality/value

This review is focused on joining the most important researches dedicated to the process of FFF-printed parts with different types reinforcing materials. By dividing the reinforcements in categories by shape/geometry and method of processing, it is possible to better quantify performance improvements.

Details

Rapid Prototyping Journal, vol. 25 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 10 July 2021

Stephanie S. Luke, David Soares, Janaye V. Marshall, James Sheddden and Özgür Keleş

Fused filament fabrication of continuous-fiber-reinforced polymers is a promising technique to achieve customized high-performance composites. However, the off-axis…

Abstract

Purpose

Fused filament fabrication of continuous-fiber-reinforced polymers is a promising technique to achieve customized high-performance composites. However, the off-axis tensile strength (TS) and Mode I fracture toughness of fused filament fabricated (FFFed) continuous-glass-fiber-reinforced (CGFR) nylon are unknown. The purpose of this paper is to investigate the mechanical and fracture behavior of FFFed CGFR nylon with various fiber content and off-axis fiber alignment.

Design/methodology/approach

Tensile tests were performed on FFFed CGFR-nylon with 9.5, 18.9 and 28.4 fiber vol. %. TS was tested with fiber orientations between 0 and 90 at 15 intervals. Double cantilever beam tests were performed to reveal the Mode I fracture toughness of FFFed composites.

Findings

TS increased with increasing fiber vol. % from 122 MPa at 9.5 vol. % to 291 MPa at 28 vol. %. FFFed nylon with a triangular infill resulted in 37 vol. % porosity and a TS of 12 MPa. Composite samples had 11–12 vol. % porosity. TS decreased by 78% from 291 MPa to 64 MPa for a change in fiber angle θ from 0 (parallel to the tensile stress) to 15. TS was between 27 and 17 MPa for 300 < θ < 900. Mode I fracture toughness of all the composites were lower than ∼332 J/m2.

Practical implications

Practical applications of FFFed continuous-fiber-reinforced (CFR) nylon should be limited to designs where tensile stresses align within 15 of the fiber orientation. Interlayer fracture toughness of FFFed CFR composites should be confirmed for product designs that operate under Mode I loading.

Originality/value

To the best of the authors’ knowledge, this is the first study showing the effects of fiber orientation on the mechanical behavior and effects of the fiber content on the Mode I fracture toughness of FFFed CGFR nylon.

Details

Rapid Prototyping Journal, vol. 27 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 5 May 2021

Pedram Parandoush, Palamandadige Fernando, Hao Zhang, Chang Ye, Junfeng Xiao, Meng Zhang and Dong Lin

Additively manufactured objects have layered structures, which means post processing is often required to achieve a desired surface finish. Furthermore, the additive…

Abstract

Purpose

Additively manufactured objects have layered structures, which means post processing is often required to achieve a desired surface finish. Furthermore, the additive nature of the process makes it less accurate than subtractive processes. Hence, additive manufacturing techniques could tremendously benefit from finishing processes to improve their geometric tolerance and surface finish.

Design/methodology/approach

Rotary ultrasonic machining (RUM) was chosen as a finishing operation for drilling additively manufactured carbon fiber reinforced polymer (CFRP) composites. Two distinct additive manufacturing methods of fused deposition modeling (FDM) and laser-assisted laminated object manufacturing (LA-LOM) were used to fabricate CFRP plates with continuous carbon fiber reinforcement. The influence of the feedrate, tool rotation speed and ultrasonic power of the RUM process parameters on the aforementioned quality characteristics revealed the feasibility of RUM process as a finishing operation for additive manufactured CFRP.

Findings

The quality of drilled holes in the CFRP plates fabricated via LA-LOM was supremely superior to the FDM counterparts with less pullout delamination, smoother surface and less burr formation. The strong interfacial bonding in LA-LOM proven to be superior to FDM was able to endure higher cutting force of the RUM process. The cutting force and cutting temperature overwhelmed the FDM parts and induced higher surface damage.

Originality/value

Overall, the present study demonstrates the feasibility of a hybrid additive and subtractive manufacturing method that could potentially reduce cost and waste of the CFRP production for industrial applications.

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Article
Publication date: 27 February 2020

Wei Liu, Zicheng Zhu and Songhe Ye

The decision-making for additive manufacturing (AM) process selection is typically applied in the end of the product design stages based upon an already finished design…

Abstract

Purpose

The decision-making for additive manufacturing (AM) process selection is typically applied in the end of the product design stages based upon an already finished design. However, due to unique characteristics of AM processes, the part needs to be designed for the specific AM process. This requires potentially feasible AM techniques to be identified in early design stages. This paper aims to develop such a decision-making methodology that can seamlessly be integrated in the product design stages to facilitate AM process selection and assist product/part design.

Design/methodology/approach

The decision-making methodology consists of four elements, namely, initial screening, technical evaluation and selection of feasible AM processes, re-evaluation of the feasible process and production machine selection. Prior to the design phase, the methodology determines whether AM production is suitable based on the given design requirements. As the design progresses, a more accurate process selection in terms of technical and economic viability is performed using the analytic hierarchy process technique. Features that would cause potential manufacturability issues and increased production costs will be identified and modified. Finally, a production machine that is best suited for the finished product design is identified.

Findings

The methodology was found to be able to facilitate the design process by enabling designers to identify appropriate AM technique and production machine, which was demonstrated in the case study.

Originality/value

This study addresses the gap between the isolated product design and process selection stages by developing the decision-making methodology that can be integrated in product design stages.

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Article
Publication date: 14 June 2018

Swapnil Sinha and Nicholas Alexander Meisel

This paper aims to identify and quantify the effects of additive manufacturing (AM) process interruption on the tensile strength of material extrusion parts, and to find…

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Abstract

Purpose

This paper aims to identify and quantify the effects of additive manufacturing (AM) process interruption on the tensile strength of material extrusion parts, and to find solutions to mitigate it.

Design/methodology/approach

Statistical analysis was performed to compare the tensile strength of specimens prepared with different process interruption time durations and different embedding methods. Subsequently, specimens were reheated at the paused layer before resuming, and tensile strengths were analyzed to observe any improvements.

Findings

Process interruption significantly reduced the tensile strength of printed parts by 48 per cent compared to non-interrupted specimens. Reheating the paused layer immediately before resuming the print improved part strength significantly by 47 per cent compared to regular process interrupted specimens and by 90 per cent compared to specimens with embeds.

Practical implications

The layer-by-layer deposition of material in AM introduces the capability for in situ embedding of functional components into printed parts. This paper shows that tensile properties are degraded during embedding due to the need for process interruption. These effects can be addressed by reheating the paused layer, providing process guidance for embedding with AM.

Originality/value

This paper provides an understanding of process interruption and embedding effects on mechanical properties of the parts, and how to improve them. The results from this experimental analysis provide crucial information toward design guidelines for multi-functional AM with embedded components.

Details

Rapid Prototyping Journal, vol. 24 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 29 August 2019

Hongbin Li, Taiyong Wang, Sanjay Joshi and Zhiqiang Yu

Continuous fiber-reinforced thermoplastic composites are being widely used in industry, but the fundamental understanding of their properties is still limited. The purpose…

Abstract

Purpose

Continuous fiber-reinforced thermoplastic composites are being widely used in industry, but the fundamental understanding of their properties is still limited. The purpose of this paper is to quantitatively study the effects of carbon fiber content on the tensile strength of continuous carbon fiber-reinforced polylactic acid (CCFRPLA) fabricated through additive manufacturing using the fused deposition modeling (FDM) process.

Design/methodology/approach

The strength of these materials is highly dependent on the interface that forms between the continuous fiber and the plastic. A cohesive zone model is proposed as a theoretical means to understand the effect of carbon fiber on the tensile strength properties of CCFRPLA. The interface formation mechanism is explored, and the single fiber pulling-out experiment is implemented to investigate the interface properties of CCFRPLA. The fracture mechanism is also explored by using the cohesive zone model.

Findings

The interface between carbon fiber and PLA plays the main role in transferring external load to other fibers within CCFRPLA. The proposed model established in this paper quantitatively reveals the effects of continuous carbon fiber on the mechanical properties of CCFRPLA. The experimental results using additively manufacturing CCFRPLA provide validation and explanation of the observations based on the quantitative model that is established based on the micro-interface mechanics.

Research limitations/implications

The predict model is established imagining that all the fibers and PLA form a perfect interface. While in a practical situation, only the peripheral carbon fibers of the carbon fiber bundle can fully infiltrate with PLA and form a transmission interface. These internal fibers that cannot contract with PLA fully, because of the limit space of the nozzle, will not form an effective interface.

Originality/value

This paper theoretically reveals the fracture mechanism of CCFRPLA and provides a prediction model to estimate the tensile strength of CCFRPLA with different carbon fiber contents.

Details

Rapid Prototyping Journal, vol. 25 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 12 October 2018

Yehia Ibrahim, Garrett W. Melenka and Roger Kempers

This paper aims to evaluate and predict the tensile properties of additively manufactured continuous wire polymer composites (CWPCs).

Abstract

Purpose

This paper aims to evaluate and predict the tensile properties of additively manufactured continuous wire polymer composites (CWPCs).

Design/methodology/approach

An open-source 3D printer was modified to print CWPCs where metal wires act as a reinforcement within a polymer matrix. The influence of different wire materials and diameters on the tensile modulus and ultimate tensile strength was studied. Different polymer matrixes were used to investigate the effect of the matrix on CWPCs’ tensile properties. The behaviour of samples was predicted analytically using the rule of mixture micromechanical approach and investigated experimentally using an American society for testing and materials standard tensile test.

Findings

Experimental results showed improvement in the elastic modulus and ultimate strength of CWPCs compared with non-reinforced specimens. Deviation between the experimental data and the analytical prediction was found to be dependent on the matrix type, wire volume fraction and wire material.

Originality/value

This paper introduces novel continuous metal wire-reinforced 3D printed composites. The continuous wire inside the print can be used as a strain gauge which can give an early alert for material failure. Applications for CWPCs include 3D-printed pressure and temperature sensors which measure the change in the wire’s electrical resistance and 3D-printed heaters which would work by supplying current through continuous wires.

Details

Rapid Prototyping Journal, vol. 24 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

Content available
Article
Publication date: 19 May 2021

Mohammad Asif Salam and Saleh Bajaba

The purpose of this study is to investigate the role of the COVID-19 health-care system quality (HSQ) and its impact on the individual (satisfaction) and social (quality…

Abstract

Purpose

The purpose of this study is to investigate the role of the COVID-19 health-care system quality (HSQ) and its impact on the individual (satisfaction) and social (quality of life [QOL]) outcomes in the context of a transformative health-care delivery system using service-dominant logic (SDL).

Design/methodology/approach

A sample consisting of 1,008 individuals who have experienced the COVID-19 health-care system was drawn from four different regions of Saudi Arabia using the simple random sampling technique. The survey was conducted using an online survey and 1,008 respondents answered, based on their experience and knowledge of the COVID-19 health-care system. Partial least squares structural equation modeling was applied to test the proposed research model.

Findings

The study findings suggest that service system satisfaction (SAT) significantly mediates the role of the HSQ in delivering and enhancing the QOL. HSQ also has a significant role to play on the SAT as well as the QOL. These findings contribute to the body of knowledge on SDL in the context of HSQ in understanding the significant role of technologies can play in enhancing service satisfaction and better QOL during a crisis such as COVID-19. This study also improves the understanding of the importance of customer-centricity, real-time visibility through tracking and tracing of service flow, agile decision-making, fewer but better-defined service objectives, and finally shaping mindsets and behaviors of all the relevant parties involved in the HSQ service delivery process.

Research limitations/implications

One of the major limitations of this study is that, although COVID-19 is an ongoing global pandemic, cross-sectional data were collected in only one country. The findings may not be generalizable across subsequent waves of the pandemic. The best practices of HSQ could be studied around the globe and the results used to support continuous improvement.

Originality/value

This study advances the understanding of the SDL in the context of a transformative health-care system for a transitional economy by focusing on individual and social well-being during an unexpected crisis such as the COVID-19 pandemic. This study also contributes toward the understanding of the roles of enabling technologies to improve the service delivery system which results in an improved SAT, as well as better QOL for the society at large. Based on SDL this research validates the HSQ model, relevant measures and its overall impact on SAT and QOL in the context of a transformative health-care service system in Saudi Arabia.

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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…

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

Keywords

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