Additive manufacture (AM) and rapid prototyping (RP) for fibre-reinforced composites.
PowerPoint
papers
Index
| Automated fibre placement (AFP). Automated tape laying (ATL). Additive manufacture (AM) and rapid prototyping (RP) for fibre-reinforced composites. |
Lecture PowerPoint |
Review papers |
Subject Index |
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Automated fibre placement (AFP) [1, 2]
Fibre placement is a process in which a multi-axis robot is used to wet-wind yarn or roving around a series of pins (or similar restraints within a mould) in a predetermined pattern. The name fibre placement is often taken to include filament winding. The restraints around which the fibres are wound permit the construction of parts without the limitations of geodesic paths. The process has been used to produce Geoform (filament wound lattice-work towers where mandrel coverage is only in specific bands) and has potential for automotive space frames. The process is perhaps more applicable to thermoplastic matrix composites where on-line consolidation and cooling permit its use without the requirement for the fibre restraints. Video with fibre placement at 2'08-2'30.
Automated fibre placement (AFP) normally uses (thermoplastic or thermoset) pre-impregnated tows (towpreg) to build up a component against a mould or mandrel surface (not around pins, but relying on the tackiness of the towpreg). The narrow tows allow more complex parts to be manufactured than when using automated tape layin, with increasing interest in tow steering [3-5].
Sacco et al [6] present a comprehensive overview of machine learning (ML) applications in composites manufacturing, with discussion of novel vision inspection software developed for the Automated Fiber Placement (AFP) process. Defect data integrated into the manufacturing process allows the inspection system to "influence several chains in the composites product lifecycle management".
German company Festo studies nature to inform innovation (biomimetics). Their 3D Cocooner [7-9], which was launched at the Hannover Fair in April 2016, uses a tripod robot to deliver (spin) 2400 tex glass fibre roving coated with UV-curing resin and position the strands into a free-standing 3D lattice structure. The current system extrudes material at 10 mm/s into a volume of 450 x 300 x 600 mm. Video
References
Automated tape laying (ATL) [1-3]
Tape laying is a computer-numerically controlled (CNC) technique similar to automated fibre placement with the obvious difference that (prepreg) reinforcement tapes are laid. The fibre delivery system usually employs a Cartesian framework for gross positioning (rather than a primarily rotational axis robot) with rotational freedoms close to the work-piece. It may be used for thermoset or thermoplastic matrix composites but is usually limited to flat or low curvature surfaces. It is often associated with high quality aerospace composites such as flight control surfaces and wing skins.
References
Additive manufacture (AM) and rapid prototyping (RP) for fibre-reinforced composites
These technologies can be classified by scale into four categories: consumer < desktop < professional < production. Rapid prototyping (RP) in currently used to indiacte products which last only a few days (e.g. for ergonomic assessment of a design). Additive manufacture is used for items sold as durable products. The ASTM Sub-Committee F42.91 published ASTM F2792-12a "Standard Terminology for Additive Manufacturing Technologies" which was withdrawn and replaced by BS ISO/ASTM 52900:2015 Additive manufacturing. General principles. Terminology. The ASTM Standard defined seven distinct Additive Manufacturing (AM) technologies for materials in general (not necessarily composites) as listed in Table 1.
| Process | Examples |
| vat photopolymerisation | stereo lithography (SL), digital light projection (DLP) |
| sheet lamination | laminated object manufacturing (LOM), ultrasonic consolidation (UC) of metal foils |
| material extrusion | fused deposition modelling (FDM) |
| material jetting | similar to ink-jet printing |
| binder jetting | HP multi-jet fusion with heat |
| directed energy deposition (DED) | electron beam, laser or plasma arc |
| powder bed fusion | laser or electron beam melting |
Researchers at MIT (USA) in collaboration with Carbitex (UK) have 3D printed morphing carbon fibre composites that fold, curl, twist and respond to a variety of stimuli (e.g. heat, light or moisture) [1, 2]. Video.
CRP Technology used selective laser sintering process to print the Windform SP ski-boot using carbon fibres in polyamide [3]
The US Oak Ridge National Laboratory (ORNL) used 3D printing technology to make a carbon fibre reinforced plastics Shelby Cobra replica using the Cincinnati Incorporated/ORNL Big Area Additive Manufacturing (BAAM) machine. The replica took six weeks to design, manufacture and assemble including 24 hours of print time. A smaller print-bead, and subsequent work by TruDesign (Knoxville), produced a Class A automotive finish on the completed vehicle [4].
The MarkForged desktop 3D composite printer uses two print heads to separately deliver either continuous aramid/carbon/glass fibre towpreg or a polyamide (PA)/polylactide (PLA) matrix for Fused Filament Fabrication (FFF) and Composite Filament Fabrication (CFF) and build up 200 μm layers. The first printer in the UK was installed at the University of Derby Institute for Innovation in Sustainable Engineering (IISE) [5-7]. Video.
Orbital Composites have introduced a coaxial extruder toolhead which can coat continuous carbon fiber (and materials such as plastic, wire, solder, epoxies, pastes, etc.) before delivery for part manufacture [8].
Two North American universities [9] have developed a hybrid “4-D printed” composite material by embedding light-responsive fibers coated with spirobenzopyran (SP) chromophores (color-sensitive molecules) into a temperature-sensitive gel. They claim the composite can be reconfigured multiple times, bending one way when exposed to light and the other way when exposed to heat, and that they designed “a single composite that creates access to a range of dynamic responses and structures”.
The University of Bristol [10, 11] have developed 3D printing of composite materials using ultrasonic standing waves to position microscopic glass fibres with a focussed laser beam to cure the epoxy matrix component.
The US Department of Energy Oak Ridge National Laboratory (ORNL) has produced a 3D printed trim-and-drill tool in carbon fibre/ABS which is over 5.3 x 1.67 x 0.45 m (L x W x H). The tool was printed in 30 h whereas the metallic equivalent would typically take 3 months to manufacture [12].
Hoa [13] has proposed 4D printing where the process combines 3D printing of a flat form that can be activated to change shape after manufacture to deform into a “curved” or “S” shape. The 3D printing process can then be faster. The materials used are long fiber composite materials where shrinkage of the matrix resin, and/or coefficients of thermal contraction which differ with layer orientation lead to shape change upon curing and cooling.
References
Strategic reports
Additional resources