FW: filament winding AFP: automated fibre placement ATL: tape laying pultrusion tube rolling John Summerscales

Filament winding continuous fibre reinforcements are precisely positioned in a pre-determined pattern on a rotating mandrel (mould tool for filament winding) normally computer numerically controlled (CNC) to permit highly automated production of axisymmetric components

Filament winding simple machine: just two axes rotation of the mandrel translation of the feed eye on an axis parallel to the machine axis complexity characterised by the number of degrees of freedom: up to six separately controlled axes usually three orthogonal and three rotational axes

Filament winding image from http://www.tifac.org.in/news/acfil.jpg

Filament winding - tension fibre tension is critical to the operation of a filament winding machine normal to have fibre tensioners (closed-loop controlled servo-driven "dancers") tension required depends on type of fibre part diameter winding pattern

Filament winding - tension fibre tension directly affects fibre volume fraction void content and, in turn, influences the strength and stiffness of the composite part. difficult to maintain tension on flat surfaces axial winding not a preferred orientation on cylinders.

Filament winding - impregnation resin impregnation image from http://www.pultrex.com/images/productimages/resin2.jpg

Filament winding - winding patterns hoop (90º) a.k.a girth or circumferential winding angle is normally just below 90° degrees each complete rotation of the mandrel shifts the fibre band to lie alongside the previous band. helical complete fibre coverage without the band having to lie adjacent to that previously laid. polar domed ends or spherical components fibres constrained by bosses on each pole of the component. axial (0º) beware: difficult to maintain fibre tension

Filament winding - winding patterns hoop : helical: polar: images from: http://www.tifac.org.in/news/acfil1.jpg http://www.tifac.org.in/news/acfil2.jpg http://www.tifac.org.in/news/acfil3.jpg

Filament winding - winding pattern Kevlar component image from http://www.tifac.org.in/news/acfil5.jpg

Filament winding - geodesic path simplest fibre orientation is the geodesic path assumes non-slip winding once winding has commenced, fixed fibre path at any point dictated by the Clairaut angle ( r.sin a = constant) where r is local radius, a is local angle at bosses, a = arcsin (rb/r) where rb = angle at the boss (polar opening) exploiting friction, it is possible to achieve non-geodesic winding within limits.

Lattice structures (anisogrid) can be produced by partial coverage and careful choice of relative band positions image from Vasiliev et al, Composite Structures, 2001, 54(2-3). GeoformTM communication masts, railway gantries, spray booms, etc

Filament winding - applications pressure vessels, storage tanks and pipes rocket motors, launch tubes Light Anti-armour Weapon (LAW) Hunting Engineering made a nesting pair in 4 minutes with ~20 mandrels circulated through the machine and a continuous curing oven. drive shafts Entec “the world’s largest five-axis filament winding machine” for wind turbine blades length 45.7 m, diameter 8.2 m, weight > 36 tonnes.

AFP: automated fibre placement multi-axis robot wet-winds fibre around a series of pins (or similar restraints within a mould) in a predetermined pattern. not limited by geodesic paths used to produce Geoform (lattice-work with coverage in specific bands) better for thermoplastic matrix composites on-line consolidation and cooling permit use without the requirement for the fibre restraints.

ATL: automated tape laying computer-numerically controlled (CNC) technique laying prepreg reinforcement tape Cartesian framework for gross positioning (rather than a primarily rotational axis robot) rotational freedoms close to the work-piece. used for thermoset or thermoplastic matrix limited to flat or low curvature surfaces high quality aerospace composites e.g. flight control surfaces and wing skins.

Pultrusion continuous constant cross-section profile normally thermoset (thermoplastic possible) impregnate with resin pull through a heated die resin shrinkage reduces friction in the die polyester easier to process than epoxy tension control as in filament winding post-die, profile air-cooled before gripped hand-over-hand hydraulic clamps conveyor belt/caterpillar track systems. moving cut-off machine ("flying cutter")

Pultrusion production of constant cross-section profiles Image from www.acmanet.org/pic/images/schematic.jpg (no longer online) Videos: Soc.Mfg.Eng (1’18”) Strongwell (1’32)

Pultrusion - design manuals by Quinn and Hartley seek uniform thickness in order to achieve uniform cooling and hence minimise residual stress. hollow profiles require a cantilevered mandrel to enter the die from the fibre-feed end.

Pultrusion -applications panels – beams – gratings – ladders tool handles - ski poles – kites electrical insulators and enclosures light poles - hand rails – roll-up doors 450 km of cable trays in the Channel Tunnel plus ...

Pultrusion (ACCS/Composolite®) Advanced Composite Construction System components: plank ............... and connectors used in Aberfeldy and Bonds Mill Lock bridges Images from .. www.ksci.com/graphics/aberf.gif ..and.. www.stroudwater.co.uk/cpsn/bonds%20mill%20bridge%203.jpg (no longer online)

Pultrusion - variations of process pulwinding/pulbraiding: fibres are wound onto the core of the pultrusion before it enters the heated die. pulforming: the profile is subjected to post-die shaping.

Tube rolling (mandrel wrapping) a technique where pre-preg is formed onto a tapered mandrel and consolidated using shrink-wrap. most often used to make fishing rod blanks