Research

10 pages, 7883 KiB

Open AccessArticle

Development of a System for Additive Manufacturing of Ceramic Matrix Composite Structures Using Laser Technology

by Stefan Polenz, Willy Kunz, Benjamin Braun, Andrea Franke, Elena López, Frank Brückner and Christoph Leyens

Materials 2021, 14(12), 3248; https://doi.org/10.3390/ma14123248 - 12 Jun 2021

Cited by 2 | Viewed by 2213

Abstract

Ceramic matrix composites (CMCs) are refractory ceramic materials with damage-tolerant behavior. Coming from the space industry, this class of materials is increasingly being used in other applications, such as automotive construction for high-performance brake discs, furnace technology, heat coatings for pipe systems and [...] Read more.

Ceramic matrix composites (CMCs) are refractory ceramic materials with damage-tolerant behavior. Coming from the space industry, this class of materials is increasingly being used in other applications, such as automotive construction for high-performance brake discs, furnace technology, heat coatings for pipe systems and landing flaps on reusable rocket sections. In order to produce CMC faster and more cost-efficiently for the increasing demand, a new additive manufacturing process is being tested, which in the future should also be able to realize material joints and higher component wall thicknesses than conventional processes. The main features of the process are as follows. A ceramic fiber bundle is de-sized and infiltrated with ceramic suspension. The bundle infiltrated with matrix material is dried and then applied to a body form. During application, the matrix material is melted by laser radiation without damaging the fiber material. For the initial validation of the material system, samples are pressed and analyzed for their absorption properties using integrating sphere measurement. With the results, a suitable processing laser is selected, and initial melting tests of the matrix system are carried out. After the first validation of the process, a test system is set up, and the first test specimens are produced to determine the material parameters. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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20 pages, 7122 KiB

Open AccessArticle

Development and Processing of Continuous Flax and Carbon Fiber-Reinforced Thermoplastic Composites by a Modified Material Extrusion Process

by Sebastian Kuschmitz, Arne Schirp, Johannes Busse, Hagen Watschke, Claudia Schirp and Thomas Vietor

Materials 2021, 14(9), 2332; https://doi.org/10.3390/ma14092332 - 30 Apr 2021

Cited by 31 | Viewed by 4028

Abstract

Additive manufacturing, especially material extrusion (MEX), has received a lot of attention recently. The reasons for this are the numerous advantages compared to conventional manufacturing processes, which result in various new possibilities for product development and -design. By applying material layer by layer, [...] Read more.

Additive manufacturing, especially material extrusion (MEX), has received a lot of attention recently. The reasons for this are the numerous advantages compared to conventional manufacturing processes, which result in various new possibilities for product development and -design. By applying material layer by layer, parts with complex, load-path optimized geometries can be manufactured at neutral costs. To expand the application fields of MEX, high-strength and simultaneously lightweight materials are required which fulfill the requirements of highly resilient technical parts. For instance, the embedding of continuous carbon and flax fibers in a polymer matrix offers great potential for this. To achieve the highest possible variability with regard to the material combinations while ensuring simple and economical production, the fiber–matrix bonding should be carried out in one process step together with the actual parts manufacture. This paper deals with the adaptation and improvement of the 3D printer on the one hand and the characterization of 3D printed test specimens based on carbon and flax fibers on the other hand. For this purpose, the print head development for in-situ processing of contin uous fiber-reinforced parts with improved mechanical properties is described. It was determined that compared to neat polylactic acid (PLA), the continuous fiber-reinforced test specimens achieve up to 430% higher tensile strength and 890% higher tensile modulus for the carbon fiber reinforcement and an increase of up to 325% in tensile strength and 570% in tensile modulus for the flax fibers. Similar improvements in performance were achieved in the bending tests. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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26 pages, 14806 KiB

Open AccessEditor’s ChoiceArticle

Fabrication and Characterisation of Aligned Discontinuous Carbon Fibre Reinforced Thermoplastics as Feedstock Material for Fused Filament Fabrication

by Lourens Gerrit Blok, Marco Luigi Longana and Benjamin King Sutton Woods

Materials 2020, 13(20), 4671; https://doi.org/10.3390/ma13204671 - 20 Oct 2020

Cited by 23 | Viewed by 3578

Abstract

In this work, aligned discontinuous fibre composite (ADFRC) tapes were developed and investigated as precursors for a novel 3D printing filament. ADFRCs have the potential to achieve mechanical performance comparable to continuous fibre reinforced composites, given sufficient fibre length and high level of [...] Read more.

In this work, aligned discontinuous fibre composite (ADFRC) tapes were developed and investigated as precursors for a novel 3D printing filament. ADFRCs have the potential to achieve mechanical performance comparable to continuous fibre reinforced composites, given sufficient fibre length and high level of alignment, and avoid many of the manufacturing difficulties associated with continuous fibres, e.g., wrinkling, bridging and corner radii constraints. Their potential use for fused filament fabrication (FFF) techniques was investigated here. An extensive down-selection process of thermoplastic matrices was performed, as matrix properties significantly impact both the processing and performance of the filament. This resulted in four candidate polymers (ABS, PLA, Nylon, PETG) which were used to manufacture ADFRC tapes with a V_f of 12.5% using the high performance discontinuous fibre (HiPerDiF) technology and an in-house developed continuous consolidation module. Tensile stiffness and strength up to 30 GPa and 400 MPa respectively were recorded, showing that a discontinuous fibre filament has the potential to compete with continuous fibre filaments. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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11 pages, 4362 KiB

Open AccessArticle

Three-Dimensional Printing of Continuous Flax Fiber-Reinforced Thermoplastic Composites by Five-Axis Machine

by Haiguang Zhang, Di Liu, Tinglong Huang, Qingxi Hu and Herfried Lammer

Materials 2020, 13(7), 1678; https://doi.org/10.3390/ma13071678 - 03 Apr 2020

Cited by 36 | Viewed by 4595

Abstract

A method for printing continuous flax fiber-reinforced plastic (CFFRP) composite parts by five-axis three-dimensional (3D) printer, based on fused filament fabrication (FFF) technology, has been developed. FFF printed parts usually need supporting structures, have a stair step effect, and unfavorable mechanical properties. In [...] Read more.

A method for printing continuous flax fiber-reinforced plastic (CFFRP) composite parts by five-axis three-dimensional (3D) printer, based on fused filament fabrication (FFF) technology, has been developed. FFF printed parts usually need supporting structures, have a stair step effect, and unfavorable mechanical properties. In order to address these deficiencies, continuous natural fiber prepreg filaments were first manufactured, followed by curved path planning for the model for generation of the G-code, and finally printed by a five-axis 3D printer. The surface quality of printed parts was greatly improved. The tensile strength and modulus of CFFRP increased by 89% and 73%, respectively, compared with polylactic acid (PLA) filaments. The flexural strength and modulus of the 3D-printed CFFRP specimens increased by 211% and 224%, respectively, compared with PLA specimens. The maximal curved bending force load and stiffness of the 3D-printed CFFRP specimens increased by 39% and 115%, respectively, compared with the flat slicing method. Advanced light structures, such as leaf springs, can be designed and manufactured by taking advantage of the favorable properties of these composites, which endow them with significant potential for application in the field of automobiles. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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14 pages, 6337 KiB

Open AccessArticle

Nature-Inspired, Ultra-Lightweight Structures with Gyroid Cores Produced by Additive Manufacturing and Reinforced by Unidirectional Carbon Fiber Ribs

by Marco Pelanconi and Alberto Ortona

Materials 2019, 12(24), 4134; https://doi.org/10.3390/ma12244134 - 10 Dec 2019

Cited by 41 | Viewed by 8551

Abstract

This article reports on a nature-inspired, ultra-lightweight structure designed to optimize rigidity and density under bending loads. The structure’s main features were conceived by observing the scales of the butterflies’ wings. They are made of a triply periodic minimal surface geometry called gyroid [...] Read more.

This article reports on a nature-inspired, ultra-lightweight structure designed to optimize rigidity and density under bending loads. The structure’s main features were conceived by observing the scales of the butterflies’ wings. They are made of a triply periodic minimal surface geometry called gyroid and further reinforced on their outer regions with a series of ribs. In this work, the ribs were substituted with carbon fiber-reinforced bars that were connected to the main structure with an innovative concept. Stereolithography was used to print a plastic component in one piece that comprised the core and the connection system. Bending tests were performed on the structures along with a Finite Element Method optimization campaign to achieve the optimum performance in terms of stiffness and density. Results show that these architectures are among the most effective mechanical solutions in respect to their weight because of their particular arrangement of material in space. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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16 pages, 11215 KiB

Open AccessArticle

Dimensional Accuracy and Mechanical Properties of Chopped Carbon Reinforced Polymers Produced by Material Extrusion Additive Manufacturing

by Evren Yasa and Kıvılcım Ersoy

Materials 2019, 12(23), 3885; https://doi.org/10.3390/ma12233885 - 25 Nov 2019

Cited by 42 | Viewed by 4709

Abstract

Fused Filament Fabrication (FFF), classified under material extrusion additive manufacturing technologies, is a widely used method for fabricating thermoplastic parts with high geometrical complexity. To improve the mechanical properties of pure thermoplastic materials, the polymeric matrix may be reinforced by different materials such [...] Read more.

Fused Filament Fabrication (FFF), classified under material extrusion additive manufacturing technologies, is a widely used method for fabricating thermoplastic parts with high geometrical complexity. To improve the mechanical properties of pure thermoplastic materials, the polymeric matrix may be reinforced by different materials such as carbon fibers. FFF is an advantageous process for producing polymer matrix composites because of its low cost of investment, high speed and simplicity as well as the possibility to use multiple nozzles with different materials. In this study, the aim was to investigate the dimensional accuracy and mechanical properties of chopped carbon-fiber-reinforced tough nylon produced by the FFF process. The dimensional accuracy and manufacturability limits of the process are evaluated using benchmark geometries as well as process-inherent effects like stair-stepping effect. The hardness and tensile properties of produced specimens in comparison to tough nylon without any reinforcement, as well as continuous carbon-reinforced specimens, were presented by taking different build directions and various infill ratios. The fracture surfaces of tensile specimens were observed using a Scanning Electron Microscope (SEM). The test results showed that there was a severe level of anisotropy in the mechanical properties, especially the modulus of elasticity, due to the insufficient fusion between deposited layers in the build direction. Moreover, continuous carbon-reinforced specimens exhibited very high levels of tensile strength and modulus of elasticity whereas the highest elongation was achieved by tough nylon without reinforcement. The failure mechanisms were found to be inter-layer porosity between successive tracks, as well as fiber pull out. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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14 pages, 5279 KiB

Open AccessArticle

Selectively Enhanced 3D Printing Process and Performance Analysis of Continuous Carbon Fiber Composite Material

by Huiyan Luo, Yuegang Tan, Fan Zhang, Jun Zhang, Yiwen Tu and Kunteng Cui

Materials 2019, 12(21), 3529; https://doi.org/10.3390/ma12213529 - 28 Oct 2019

Cited by 24 | Viewed by 3872

Abstract

Aiming at the limited mechanical properties of general thermoplastic 3D printed models, a 3D printing process method for selective enhancement of continuous carbon fiber composite material is proposed. Firstly, the selective enhanced double nozzle working mechanism and crafts planning process are put forward. [...] Read more.

Aiming at the limited mechanical properties of general thermoplastic 3D printed models, a 3D printing process method for selective enhancement of continuous carbon fiber composite material is proposed. Firstly, the selective enhanced double nozzle working mechanism and crafts planning process are put forward. Then, based on the double nozzle carbon fiber 3D printing device, test samples are printed by polylactic acid (PLA) and carbon fiber material, and the test samples are enhanced by inserting layers of continuous carbon fiber material. The performance test of the samples is carried out. Experiment results show that when the volume fraction of continuous carbon fiber material increases gradually from 5% to 40%, the tensile strength increases from 51.22 MPa to 143.11 MPa. The performance improvement curve is fitted through experimental data. Finally, field scanning electron microscopy is used to observe the microscopic distribution of continuous fibers in the samples. The results of the research lay the foundation for the performance planning of 3D printed models. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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10 pages, 1921 KiB

Open AccessCommunication

Novel Continuous Fiber Bi-Matrix Composite 3-D Printing Technology

by Adi Adumitroaie, Fedor Antonov, Aleksey Khaziev, Andrey Azarov, Mikhail Golubev and Valery V. Vasiliev

Materials 2019, 12(18), 3011; https://doi.org/10.3390/ma12183011 - 17 Sep 2019

Cited by 44 | Viewed by 5564

Abstract

A new paradigm in continuous fiber-reinforced polymer fused filament fabrication based on a thermoset-thermoplastic bi-matrix material system is proposed and proved. This totally new 3-D printing concept has the potential to overcome the drawbacks and to combine the advantages of separate thermoset and [...] Read more.

A new paradigm in continuous fiber-reinforced polymer fused filament fabrication based on a thermoset-thermoplastic bi-matrix material system is proposed and proved. This totally new 3-D printing concept has the potential to overcome the drawbacks and to combine the advantages of separate thermoset and thermoplastic-based, fused filament fabrication methods and to advance continuous fiber-reinforced polymer 3-D printing toward higher mechanical performances of 3-D printed parts. The novel bi-matrix 3-D printing method and preliminary results related to the 3-D printed composite microstructure and performances are reported. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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24 pages, 8870 KiB

Open AccessArticle

Piezoresistive Behaviour of Additively Manufactured Multi-Walled Carbon Nanotube/Thermoplastic Polyurethane Nanocomposites

by Myoungsuk Kim, Jaebong Jung, Sungmook Jung, Young Hoon Moon, Dae-Hyeong Kim and Ji Hoon Kim

Materials 2019, 12(16), 2613; https://doi.org/10.3390/ma12162613 - 16 Aug 2019

Cited by 29 | Viewed by 3623

Abstract

To develop highly sensitive flexible pressure sensors, the mechanical and piezoresistive properties of conductive thermoplastic materials produced via additive manufacturing technology were investigated. Multi-walled carbon nanotubes (MWCNTs) dispersed in thermoplastic polyurethane (TPU), which is flexible and pliable, were used to form filaments. Specimens [...] Read more.

To develop highly sensitive flexible pressure sensors, the mechanical and piezoresistive properties of conductive thermoplastic materials produced via additive manufacturing technology were investigated. Multi-walled carbon nanotubes (MWCNTs) dispersed in thermoplastic polyurethane (TPU), which is flexible and pliable, were used to form filaments. Specimens of the MWCNT/TPU composite with various MWCNT concentrations were printed using fused deposition modelling. Uniaxial tensile tests were conducted, while the mechanical and piezoresistive properties of the MWCNT/TPU composites were measured. To predict the piezoresistive behaviour of the composites, a microscale 3D resistance network model was developed. In addition, a continuum piezoresistive model was proposed for large-scale simulations. Full article

(This article belongs to the Special Issue Additive Manufacturing of Fiber Composites)

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