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

1. FW: filament windingAFP: automated fibre placementATL: tape laying pultrusion tube rolling John Summerscales

2. 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

3. 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 bythe number of degrees of freedom: • up to six separately controlled axes • usually three orthogonal and three rotational axes

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

5. 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

6. 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 nota preferred orientation on cylinders.

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

8. 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 bandhaving 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

9. 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

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

11. 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.

12. 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).

13. 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 minuteswith ~20 mandrels circulated through the machineand 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.

14. AFP: automated fibre placement • multi-axis robot wet-winds fibrearound 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.

15. 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 compositese.g. flight control surfaces and wing skins.

16. 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")

17. 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)

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

19. 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 ...

20. 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)

21. 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.

22. Tube rolling • a technique where pre-preg isformed onto a tapered mandreland consolidated using shrink-wrap. • most often used to make fishing rod blanks