Patent Description:
It is known to use composite materials comprising a matrix reinforced with fibre reinforcement material such as carbon fibre for components to provide a desirable combination of properties, such as strength and low weight.

It is known to form composite components by providing a lay-up comprising a plurality of plies of fibre reinforcement material, for example over a lay-up surface which defines a profile for the component.

Woven composite structures have been proposed for use in component manufacture owing to desirable properties relating to structural integrity. However, woven preforms are generally provided in sheets, which may be difficult to use to form a complex shape, such as a shape having multiple members. In particular, there are challenges in joining woven structures at a junction between members.

<CIT> discloses a potential means by which four arms may be joined together in a cruciform cross-section structure.

<CIT> discloses a woven composite component having a T-piece junction, wherein a plurality of noodle elements <NUM> is oriented in the warp direction in the centre as a filler and said noodle elements are integrally woven with the warp tows of both of the feeder portions <NUM> and <NUM>, rather than crossed at the T-piece junction to pass around one noodle element.

According to a first aspect there is disclosed a woven composite component for an aerospace structure or according to claim <NUM>.

<FIG> schematically shows a cross-sectional view of an example composite component <NUM>, comprising a compound member <NUM> extending from a junction <NUM> with a feeder member <NUM>. As illustrated, the example composite component <NUM> is in the form of a T-piece, with the compound member <NUM> extending substantially orthogonally with respect to the feeder member <NUM> but it will be appreciated that other configurations are possible and envisaged in the context of the present invention.

Rather than being arranged contiguously end-to-end such that fibre-reinforcement material can extend straightforwardly into the compound member <NUM> from the feeder member, the compound member extends from a junction <NUM> mid-way along the feeder member. The feeder member <NUM> has first and second feeder portions <NUM>, <NUM> disposed either side of the junction <NUM>. Accordingly, the component <NUM> has a relatively complex shape owing to the joining together of multiple members.

<FIG> depicts layers of fibre-reinforcement material, in particular a compound set <NUM> of warp tows extending from the first and second feeder portions <NUM>, <NUM> to the compound portion <NUM>. As shown in <FIG>, some of the warp tows of the compound set <NUM> extend from the first feeder portion into the compound member <NUM> via the junction <NUM>, whereas others extend from the second feeder portion into the compound member <NUM> via the junction <NUM>.

Owing to the turning of the tows at the junction <NUM>, there can be a reduction in fibre volume fraction within a formed composite component. For this reason, it has previously been considered to provide additional fibre reinforcement material at the junction in the form of a noodle element at the junction, for example comprising a bundle of fibre-reinforcement material. Such previous attempts have provided the noodle element in a central location of the junction, with two effectively separate sets of plies extending around the noodle on different sides.

However, the inventors have determined that in such arrangements the noodle element is poorly integrated with the woven structure in its preform state, therefore leading to difficulties in handing and manipulating the preform ready for forming a composite component.

According to the present invention, the inventors have determined that it can be advantageous to bind a noodle element <NUM> within the woven structure as shown in <FIG>. In particular, by causing the compound tows extending from opposing feeder portions <NUM>, <NUM> to cross each other as they extend around the noodle element, the noodle element can be bound within the woven structure. Additionally, by causing the tows to cross and extend around the noodle element <NUM>, the noodle element <NUM> acts as a guide for the profile of the woven structure, in particular by defining a specific location at which the tows are to turn along the lateral extent of the preform. Accordingly, a noodle may be inserted to not only reinforce and increase the fibre volume fraction at a T-piece junction, but also to ensure compliance with the intended location of the T-piece junction and where the fibre reinforcement material is to turn from the feeder member to the compound member.

As shown in <FIG>, there are several layers of warp tows through a thickness direction in each of the first and second feeder portions <NUM>, <NUM>. The compound set <NUM> of warp tows comprises a set of crossing tows, with each crossing tow crossing with a corresponding crossing tow from the opposing feeder portion at the junction as they pass around the noodle element <NUM>. In the example of <FIG>, each compound tow is a crossing tow, but in other examples the set of compound tows may comprise warp tows which do not cross with a corresponding tow from the opposing feeder portion.

In the particular example shown in <FIG>, the crossing tows pass on two opposing sides of the noodle element <NUM> to define an "eye" <NUM> (i.e. a passageway delimited by the crossing tows) through which the noodle element extends. In particular, the component <NUM> has a base side extending between the feeder portions <NUM>, <NUM> and distal to the compound member (i.e. away from the compound member) and a compound side at an interface between the junction and the compound member. The noodle element <NUM> is located in an eye <NUM> defined by the crossing set of warp tows, including warp tows from the first feeder portion that extend past the noodle on both the base side and the compound side, and warp tows from the second feeder portion that extend past the noodle on both the base side and the compound side.

It should be appreciated that <FIG> is a simplified example and there may be more layers of fibre-reinforcement material which together define more eyes for noodle elements, and a junction may comprise one or more than one noodle elements extending through respective eyes. A variant example substantially as described above with respect to <FIG>, but comprising two noodle elements <NUM>, <NUM>' in respective eyes <NUM>, <NUM>' is shown in <FIG>. As shown in <FIG>, in this example there are commensurately more compound tows <NUM> which collectively define the eyes <NUM>, <NUM>'. As stated above, the noodle element <NUM> may comprise a bundle of fibre-reinforcement material. The noodle element <NUM> may have a tow weight (corresponding to a number of fibre filaments) which is greater than a tow weight of the warp tows in the feeder member the compound member. For example, the noodle element may comprise a <NUM> tow (e.g. having a tow weight of <NUM> per meter), whereas the warp tows may comprise a <NUM> tow (e.g. having a tow weight of <NUM> per meter).

As shown in <FIG>, the component <NUM> comprises capping plies <NUM> extending from the first and second feeder portions <NUM>, <NUM> to the compound portion <NUM>. The capping plies <NUM> define an outer surface of the component, and do not cross or interlace with the crossing tows described above. The capping plies <NUM> may be applied as a separate layer of the preform from the compound tows <NUM>, or may be formed integrally with the compound tows <NUM> in a multi-layer weave. By providing the capping plies, the component <NUM> may be provided with a relatively smooth outer profile, particularly at the junction, by overlaying the crossing tows.

As further shown in <FIG>, there is a base ply <NUM> extending from the first feeder portion <NUM> to the second feeder portion <NUM> and defining an outer surface of the feeder member on a side opposite the compound member <NUM>. As with the capping plies <NUM>, the base ply can provide a relatively smooth outer profile of the component, particularly at the junction where it overlays the crossing tows. In manufacturing, the base ply is applied as a separate layer of the preform after the compound tows <NUM> (including crossing tows) are woven to form the crossing structure shown in <FIG>. The capping plies <NUM> and the base ply may each be either a woven ply (for example a 2D weave, or a multi-layer weave), or a ply of unidirectional fibre-reinforcement material.

To aid the further discussion of multi-layer weaves, selected weave terminology is discussed below with reference to <FIG> (comprising <FIG> shows an example woven structure <NUM> comprising a plurality of warp tows W, B extending along a warp direction P. Although not shown, the structure <NUM> further comprises a plurality of weft tows extending along a weft direction F. Although the invention extends to examples in which the woven composite or associated preform comprises two dimensional woven structures (i.e. rather than multi-layer woven structures as also disclosed herein), the example of <FIG> is a multi-layer structure. In a multi-layer weave, there are multiple layers of weft tows extending along a weft direction and layered in a thickness direction of the weave, with warp tows extending along a substantially orthogonal warp direction at respective locations along the weft direction. Each location along the weft direction occupied by one or more warp tows superposed on each other through the thickness direction is referred to herein and in the art as a "stack", such that there are a plurality of stacks defined along the weft direction by respective sets of one or more warp tows. A common configuration of stacks in a multi-layer weave is to provide an alternating arrangement of warp stacks Wand binding stacks B as shown in <FIG>, with binding stacks being stacks in which the or each warp tow is interlaced with weft tows to bind the weft tows (i.e. moving between layers of weft tows, or moving between warp tow positions defined between such layers), whereas warp stacks are stacks in which the or each warp tow extends without interlacing with weft tows (e.g. remaining between the same two layers of weft tows, or remaining at the same warp tow position).

<FIG> shows cross-sectional slices of the woven structure <NUM> normal to the weft direction F at lateral positions along the weft direction corresponding to a warp stack W and a binding stack B. The woven structure is described as a multi-layer woven structure herein as it comprises a plurality of layers of weft tows <NUM> (shown in cross section) defining a plurality of warp tow positions between the layers of weft tows. As shown in <FIG>, in the warp stack W the warp tows <NUM> extend along the warp direction at constant warp tow positions (i.e. remaining in the same warp tow position between weft layers). In contrast, in the binding stack B a warp tow <NUM> extends through the thickness direction of the woven structure between opposing sides to define a multi-layer weave pattern. In this particular example, the multi-layer weave type is an orthogonal through-thickness weave having a float number of two, meaning that each binding warp tow extends through the thickness from side to side of the woven structure, and passes over two weft tows before returning.

<FIG> shows an example woven preform <NUM> for a warp stack for the example component <NUM> of <FIG>, shown in cross-section normal to the weft direction (i.e. in the plane of a thickness direction T and a longitudinal direction). The woven preform has a feeder region <NUM> corresponding to the feeder member <NUM> of <FIG>, and a compound region <NUM> corresponding to the compound member <NUM> of <FIG>. By way of simplified example, four warp tow positions are illustrated in each of the regions by boxes, with warp tows <NUM>, <NUM>, <NUM>, <NUM> extending through adjacent warp tow positions along a thickness direction of the preform that will be referred to herein as warp tow positions <NUM>, <NUM>, <NUM>, <NUM> respectively. Although not shown, the woven preform comprises a plurality of layers of weft tows extending orthogonal to the view of <FIG>, so as to define the warp tow positions therebetween.

<FIG> shows the warp tows <NUM>-<NUM> extending longitudinally along the feeder region <NUM> until reaching a junction with the compound region <NUM>, where the warp tows are woven around the noodle element <NUM> as described above with respect to <FIG>. As shown by the dashed lines separately circumscribing tow positions <NUM> and <NUM> (together) and <NUM> and <NUM> (together), the feeder region <NUM> comprises two leaves corresponding to the respective feeder portions <NUM>, <NUM> of the composite component <NUM> of <FIG>, with first and second warp tows <NUM>, <NUM> extending through a first leaf, and third and fourth tows <NUM>, <NUM> extending through a second leaf in this example.

The first tow <NUM> extends from the first warp tow position <NUM> within the first leaf of the feeder region <NUM> to the third warp tow position <NUM> within the compound region <NUM>, passing the noodle element <NUM> on a side proximal to the compound region <NUM> (a "compound side" as described above with reference to <FIG>), and crossing with third and fourth tows <NUM>, <NUM> from the second leaf.

The second tow <NUM> extends from the second warp tow position <NUM> within the first leaf of the feeder region <NUM> to the fourth warp tow position <NUM> within the compound region <NUM>, passing the noodle element on a side proximal to the feeder region <NUM> (a "base side" as described above with reference to <FIG>), and crossing with third and fourth tows <NUM>, <NUM> from the second leaf.

The third tow <NUM> extends from the third warp tow position <NUM> within the second leaf of the feeder region <NUM> to the first warp tow position <NUM> within the compound region <NUM>, passing the noodle element <NUM> on a side proximal to the feeder region <NUM> (the "base side" as described above), and crossing with first and second tows <NUM>, <NUM> from the first leaf.

The fourth tow <NUM> extends from the fourth warp tow position <NUM> within the second leaf to the second warp tow position <NUM> within the compound region <NUM>, passing the noodle element <NUM> on a side proximal to the compound region <NUM> (the "compound side" as described above), and crossing with first and second tows <NUM>, <NUM> from the first leaf.

The above example illustrates how crossing tows passing each other and around the noodle element can together define an eye for the noodle element to pass through.

The expression "leaf" is used with respect to the two leaves of the feeder region <NUM> because these two separate portions are separable from one another away from the junction, so as to form a feeder member <NUM> as described above with respect to <FIG>. In particular, it will be appreciated that in a multi-layer weave structure, binding warp tows in binding stacks of the weave in the feeder region n306 may only extend between warp tow positions associated with the respective leaf, such that the leaves remain separable. In contrast, warp tows (e.g. the same warp tows) may extend to other warp tow positions or throughout a thickness of the weave in the compound region.

In the example described above with respect to <FIG>, the warp tows <NUM>-<NUM> that cross each other are located in the same stack, such that away from the junction they are superposed on one another along the thickness direction. Accordingly, it should be appreciated that the crossing of the warp tows necessitates a lateral deflection of the warp tows at the point of crossing. It is thought that this can be accommodated owing to the generally lower fibre volume fraction in the location of the junction in the formed component <NUM>, where two feeder portions of relatively low thickness combine to provide a compound tow having a greater thickness.

It should be appreciated that each individual stack in a multi-layer weave need not have a quantity of warp tows sufficient for defining an eye for the noodle - i.e. with warp tows from both leaves extending past the noodle on both the compound and base sides, crossing with the respective other tows to define the noodle. Instead, the eye for the noodle may be cumulatively defined by several stacks of the weave. In particular, some stacks may comprise fewer warp tows than the minimum of four required to create the structure defined above. By way of example, <FIG> shows four laterally adjacent stacks A, B, C, D over a longitudinal extent corresponding to that shown in <FIG>, and with a longitudinal position corresponding to the crossing location and noodle indicated in hatching. In the variant example of <FIG>, tows corresponding to the four tows <NUM>-<NUM> of <FIG> which collectively define the eye around the noodle element <NUM> are located in different stacks of the multi-layer weave, with tows <NUM>-<NUM> in stacks A-D respectively. In other examples, two or more (or all) of the respective tows defining the eye may be located in the same stack.

Nevertheless, it may be that in some examples, at least some of the stacks in the weave comprise warp tows configured to define an eye around the noodle within the stack itself. Although <FIG> does not show features of a multi-layer weave away from the junction, this is because it depicts an example warp stack in which the warp tows extend generally longitudinally within respective warp tow positions, without inter-layer weaving. However, it should be appreciated that in binding stacks one or more warp tows may extend between warp tow positions within the feeder region <NUM> (e.g. within the respective leaf of the feeder region) and/or the compound region <NUM> to define a multi-layer weave. For example, in binding stacks the weave may comprise a layer-to-layer angle interlock weave, a through-thickness angle interlock weave, or an orthogonal through-thickness weave, all of which are terms of the art.

A method of manufacturing a preform for a woven composite component will now be described with reference to the preform <NUM> of <FIG>. The method comprises weaving a preform as described above with respect to <FIG>, and subsequently separating the feeder leaves of the feeder region, for subsequently forming a composite component having respective feeder portions <NUM>, <NUM> as described above with respect to <FIG>. Separation of the leaves simply refers to re-orienting them to extend away from the junction in a manner corresponding to the arrangement of the feeder portions <NUM>, <NUM> as shown in <FIG>.

The preform can be woven using a loom configured to receive warp tows from a warp tow supply, and configured to weave the warp tows around weft tows inserted along the weft direction as is known in the art. The loom may be of any suitable type as is known in the art. For complex weaves, the loom may be programmable (i.e. configured for computer control) to form the woven preform with weave patterns based on computer-readable instructions. Such a loom may be referred to as a computer-controlled jacquard loom.

As is known in the art, a loom can be controlled to separate respective sets of warp tows to define an opening for insertion of a weft tow between them. For example, a set of warp tows may be lifted to an upper side of the opening so as to pass over the weft tow, whereas another set may extend below the opening so as to pass under the weft tow. After insertion of the weft tow, the same or different sets of warp tows can then be repositioned to define another opening for reception of a weft tow.

To form the woven preform <NUM> as described above, the loom may be controlled so that a first subset of the crossing tows <NUM> are caused to cross each other along the thickness direction (e.g. by drawing a warp tow from a relatively higher warp tow position to an underside of an opening in the loom, and drawing a warp tow from a relatively lower warp tow position to an upper side of the opening) prior to insertion of the noodle element. The noodle element may then be received in the loom adjacent to the crossing tows (e.g. in the opening between them). After inserting the noodle element, a second subset of crossing tows may be caused to cross each other, for example by drawing a warp tow extending around an upper side of the noodle element to a relatively lower warp tow position, and by drawing a warp tow extending around a lower side of the noodle element to a relatively higher warp tow position. Accordingly, the first and second subsets of crossing tows can be oriented around the noodle element to define an eye for the noodle element as discussed herein.

To form a composite component from the preform, the preform may be transferred to a die or mould which defines a near net shape for the component, and a matrix material (such as a resin, for example epoxy resin) can be transferred to the die or mould. The matrix material and fibre-reinforcement can then be cured (for example under elevated temperature and/or pressure) to provide the formed composite component. A suitable fibre-reinforcement material for any reform or component disclosed herein may be carbon fibre, but it will be appreciated that any suitable fibre reinforcement material can be used.

While the composite component <NUM> of <FIG> has a T-piece configuration, as does the associated woven preform <NUM> of <FIG>, it should be appreciated that a component comprising a compound member and feeder member as described herein can take any suitable shape.

Merely as a further example, <FIG> shows an I-beam structure <NUM> that has two feeder members at either end of a compound member <NUM>, each feeder member having respective first and second feeder portions <NUM>, <NUM>. As will be appreciated, the I-beam structure may be formed from a preform having a compound region with two feeder regions at either end, with respective T-piece junctions comprising noodle elements therebetween as discussed above.

A further example composite component <NUM> is shown in <FIG>. The component <NUM> is a twin-vane section for a gas turbine engine, having compound members <NUM> and feed members (having feeder portions <NUM>, <NUM>) as described above forming aerodynamic vanes and platforms respectively. While shown schematically in <FIG>, the component <NUM> may be semi-annular for integration into an annular ring of like components disposed around a central axis. The platforms formed of the feeder portions <NUM>, <NUM> may extend substantially circumferentially, whereas the vanes formed of the compound members <NUM> may extend substantially radially.

Claim 1:
A woven composite component (<NUM>) for an aerospace structure or machine, comprising:
a compound member (<NUM>) extending from a T-piece junction (<NUM>) with a feeder member (<NUM>), a noodle element (<NUM>) extending in a weft direction (F) through the junction (<NUM>);
wherein the feeder member (<NUM>) comprises first and second feeder portions (<NUM>,<NUM>) either side of the T-piece junction (<NUM>), each feeder portion (<NUM>,<NUM>) comprising warp tows extending towards the T-piece junction (<NUM>);
wherein there is a compound set (<NUM>) of warp tows extending from the first and second feeder portions (<NUM>, <NUM>), each turning at the T-piece junction (<NUM>) to define warp tows for the compound member (<NUM>); and
wherein, there is a crossing set of warp tows belonging to the compound set (<NUM>), the crossing set comprising warp tows from the first feeder portion (<NUM>) and warp tows from the second portion (<NUM>) which cross each other at the T-piece junction (<NUM>) to pass around the noodle element (<NUM>).