GB2309928A

GB2309928A - Production of a curved fibre-resin composite element

Info

Publication number: GB2309928A
Application number: GB9702424A
Authority: GB
Inventors: Frank Kocian; Markus Wunsch; Uwe Reifegerste; Karsten Reifegerste
Original assignee: Deutsche Forschungs und Versuchsanstalt fuer Luft und Raumfahrt eV DFVLR
Current assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Priority date: 1996-02-06
Filing date: 1997-02-06
Publication date: 1997-08-13
Anticipated expiration: 2017-02-06
Also published as: GB9702424D0; DE19604275C2; DE19604275A1; FR2744464A1; GB2309928B; FR2744464B1

Description

1 Process for the Production of a Structural Element 2309928 The invention

relates to a process for the production of segments of structural elements which extend along a line of curvature and on which forces act with force components extending transversely to the line of curvature, designated in the following as transverse force components.

Structural eleMents of this type are required in many cases in aeronautical engineering and space technology or also in automotive engineering and have so far been produced preferably fror. met-al.

Curved st-ructural elements consisting of a fibre composite material 2re certainly known. However, in these the fibres of the fibre composite run along the line of curvature and so they are not suitable for absorbing transverse force components since, on the one hand, the fibres of fibre composite materials cannot absorb transverse force components and, on the other hand, these transverse force components represent shearing forces easily damaging the fibre composite in such a structure and so the fibre comnosite materials known so far are not suitable for structural elements of this type.

The ob-ect underlying the invention is, therefore, to make a J process for the production of the generic structural elements available which offers the possibility of producing these structural elements in an advantageous light-weight -onstruction.

2 - This object is accomplished in accordance with the invention, in a process of the type described at the outset, in that the structural elements are produced from a fibre composite, that the fibre composite results from laying out fibres in several fibre layers located on top of one another, and that in the segment at least one fibre layer has fibre strand portions arranged to follow one another in the direction along the line of curvature, these strand.portions extending at an angle to the line of curvature, and that the fibre layers extend in surface areas which run parallel or at an acute angle to a plane defined by the line of curvature and the respective, operative transverse force component.

The inventive solution makes a process available which enables the technology of the production of fibre composite materials to also be used in such segments of structural elements which are acted upon with transverse force components and allows the advart-ages of the fibre composite materials to take effect.

The inventive.process has the particular advantage that an adaptation of the segment of the structural element acted upon by transverse force components to these transverse force components is possible in a simple manner in that the angled course of the fibre strand portions relative to the line of curvature can be adapted to the effect of the force in such a wav that the transverse force compenent acts on the fibre strands essentially in the form of pressure and traction forces, the adaptation of the course of the fibre strand portions at an angle to the line of curvature also being dependent on the pressure and traction forces which the individual fibre strand portions are capable of absorbing.

In principle, it would be possible for the fibre strand portions which follow one another in the direction along the line of curvature to always be located next to one another in one direction. It is, however, particularly advantageous when the fibre strand portions of a fibre layer following one another in the direction along the line of curvature are laid out such that one of the fibre strand portions intersects the line of curvature with a positive angle and the next following strand portion intersects the line of curvature with a negative angle. This has the advantage that it is then possible to distribute the transverse forces in the form of pressure and traction forces acting in two different directions.

In this respect, the fibre strand portions could, in principle, be designed as bent portions. However, a particularly simple and advantageous solution provides for the fibre strand portions to extend along straight sections of a zigzag line, the points of reversal of which are located on both sides of the line of curvature, wherein the zigzag line can be any optional, also irregular zigzag line.

With respect to the geometrical design, it is particularly advantaaeous when the line of curvature extends in a central region located between the points of reversal so that the points of reversal are located on both sides of the line of curvature and thus the f-ibre strand portions each extend through the segment of the structural element whilst intersecting the line of curvature.

A particularly favourable solution provides for the line of curvature to extend approximately centrally between the points of reversal.

In addition or alternatively to the process described in the above, a variation of the inventive solution provides for the structural elements to be produced from a fibre composite, for the fibre composite to result from laying out fibres in several consecutive fibre layers, for at least one fibre layer of the fibre composite to have fibre strand portions which extend at an angle to cross-sectional areas extending at right angles to the line of curvature and for the fibre layers to extend in surface areas which run parallel or at an acute angle to a plane defined by the line of curvature and the transverse force comnonents.

With resiDect to several embodiments, this inventive solution com-orises the solution described at the outset and thus also the advantages described in conjunction with it.

It comes closer, in principle, to the solution described at the ')utset when the consecutive fibre strand portions form with one another an angle which is smaller than 1800, wherein this definition of the variation of the inventive solution described above also offers the possibility of havina individual fibre strand portions running tangentially to the line of curvature in order to absorb particular transverse forces acting, for example, on both sides of a curvature.

A particularly advantageous solution provides for the fibre strand portions of this fibre layer to extend at least in partial sections thereof from one point of reversal located on one side of the line of curvature to another point of reversal located on the same side of the line of curvature.

In order to keep the structural element as compact as possible and, in particular, keep the height of the individual f ibre layers as low as possible, it is advantageously provided for the fibre strand portions to be laid out such that they extend without overlapping within each individual fibre layer of the finished structural element. This means that unnecessary elevations of the individual fibre layer, which would result with an overlapping of the individual fibre strand portions, are avoided.

in order to attain, in particular, an intimate bonding of the individual fibre layers with one another, it is preferably provided for the fibre layers laid one on top of the another to be pressed to one another by means of a pressing procedure operative transversely to the surface area of the fibre layers. This means that the individual fibre layers come into intimate contact with one another which is conducive not only to the compactness of the structural element but also to its stability.

Within the scope of the inventive solution described thus far it has been assumed that each fibre layer is built up of consecutive fibre strand portions.

- 6 The bearing strength and rigidity of the structural element may, however, be increased when each fibre layer is built up of groups of fibre strand portions and " each group comprises several fibre strand portions extending next to one another. These groups are preferably built up such that each group comprises the same number of fibre strand portions extending next to one another.

In the simplest case, the fibre strand portions of one group extend parallel to one another.

The fibre strand portions of each group can either be laid out simultaneously with one another in the same direction or it is possible to lay out different fibre strand portions of the group by laying out a fibre with different directions when seen in the longitudinal direction of the line of curvature.

It is, in principle, possible with the inventive process to lay out each fibre strand portion as an individual fibre strand portion. With respect to as economical a process as possible it is, however, advantageously provided for the individual fibre strand portions to be sections of a continuously laid out fibre.

This fibre is preferably laid out such that the individual fibre strand portions extend between two deflection points of the continuously laid out fibre, wherein the fibre is deflected at the deflection points each time into a different direction, thereby forming the next following fibre strand portion.

7 - A particularly advantageous process, particularly when fibre strand portions are intended to be laid out in groups of two, provides for the fibres comprising the fibre strand portions of a group of two extending next to one another to be deflected in the region of the same deflection points. This has the advantage that the number of deflection points can be reduced and, nevertheless, as large a number of fibre strand portions as possible can be laid out in one fibre layer.

This may be realised particularly simply when one of the fibres forming the two fibre strand portions extending next to one another winds around the deflection point with an open loop and the other fibre winds around the deflection point with a closed loop.

Each deflection point could, in principle, be a geometrical point which determines the location where the fibre is deflected.

It is, however, particularly advantageous when the fibre is laid around a deflecting element in the region of each deflection point, and thus the fibre itself and, in particular, the fibre strand portions formed by it are aligned in a defined mariner by means of the deflecting element.

The provision of the deflecting elements provides, in particular, the possibility of laying the fibre around the deflecting elements with tension in the longitudinal direction of the fibre and thus also of laying out the fibre strand portions with tension in the longitudinal direction of the fibre.

- 8 The deflecting elements may be designed particularly advantageously from a constructional point of view such that they form a member rising above a base surface for a lowest fibre layer.

In the simplest case, each deflecting element is thereby of a pin-like design.

With respect to the structure of the structural element resulting overall, no details have been given in conjunction with the preceding explanations concerning the individual embodiments. One advantageous embodiment, for example, provides for the fibres of all the fibre layers to form a structure filling the segment of the structural element over the entire surface area. This results, in particular, when the fibres are fibre bundles consisting of individual fibres and a cross section of the fibre bundles within the structural element can be made oval in shape, in particular by pressing the individual fibres in the direction transversely to the surface areas of the fibre layers.

Alternatively thereto, it is provided for the fibres of all the fibre layers to form a structure filling the segment of the structural element in a latticed manner. This is sufficient in many cases and, in particular, a lattice-like structure allows the provision, in addition, of a filler which can give the structural element addit-ional advantageous properties.

9 No details concerning the relative position of the fibre strand portions and different fibre layers have been given in conjunction with the embodiments explained thus far.

It isf for example, advantageous, particularly in order to obtain as uniform a structure of the structural element as possible, when the fibre strand portions of fibre layers arranged one above the other are arranged so as to be offset relative to one another in the direction along the line of curvature and thus the fibre strand portions are arranged so as to be distributed as uniformly as possible throughout the fibre layers as a whole.

In this respect, a preferred solution provides for the fibre strand portions of two consecutive fibre layers which correspond to one another to be arranged so as to be offset relative to one another by the same distance. This is expedient, in particular, when the arrangement of the fibre strand portions is essentially identical in the corresponding fibre layers so that an essentially homogeneous distribution of the fibre strand portions is obtained, in particular with a distance which amounts to a fraction - preferably an integral fraction - of the distance between two fibres extending in the same way relative to the line of curvature.

It would, in principle, be possible to build up the fibres from individual filaments. It is, however, particularly advantageous when the fibres are fibre bundles produced from individual filaments or also rovings.

For the production of a fibre composite material it is preferably provided for the fibres to be wetted during the production of the segment of the structural element with a material which can be hardened or caused to solidify.

This is possible, for example, when the fibres are first laid out and then wetted with a material which can be hardened or caused to solidify.

Resins or other polymer matrix materials can be used, for example, as materials which can be hardened, melts, glasses or metals, for example, as materials which can be caused to solidify.

Alternatively thereto, it is provided for each fibre to be laid out as a fibre wetted with the material which can be hardened or caused to solidify.

No details have so far been given in conjunction with the preceding explanations of the individual embodiments with respect to the laying out of the fibres. It would, for example, be possible to lay out the fibre strand portions manually. It is, however, particularly advantageous when the fibre strand portions are laid out by a manipulator, for example a compute r-contro 1 led manipulato-r, wherein the position of the individual fibre strand portions in the individual fibre layers can be specified to the manipulator.

In this respect, it is preferably provided for the fibre strand portions to be laid out by means of a movement of the manipulator which lays out the fibre strand portions so as to 11 -- -, n ' - 1 1 - extend from one point of reversal to the other point of reversal.

In this respect, it is possible for the manipulator to lay out the fibre strand portions individually.

This is expediently done by the manipulator cutting the individual fibre strand portions from a continuous fibre.

This may, for example, be realised during the laying out of the fibre strand portions along a-zigzag line when the manipulator cuts the fibre each time after laying out one fibre strand portion and ahead of a point of reversal and following the point of reversal- begins again with the laying out of the next fibre strand portion.

Alternatively to the laying out of the individual, separat-e fibre strand portions, another advantageous solution provides z for the manipulator to lay out the fibre strand portions in the form of a continuous fibre.

In this respect, it is preferably provided for the continuous fibre to extend from point of reversal to point of reversal.

Additionai- features and advantages of the invention are the subject matter of the following description as well as the drawings illustrating several embodiments.

In the drawings:

12 - Figure 1 shows a schematic illustration of a segment of a curved structural element and the position of a line of curvature thereof; Figure 2 shows a perspective view of a concrete embodiment of an inventive structural element in the form of a reinforcing ring for a wheel rim; Figure 3 shows a cross section on one side of an axis of rotation through the wheel rim in Figure 2 with a reinforcing ring inserted; Figure 4 shows a sectional illustration of all the fibre layers located one above the other for the production of the reinforcing ring illustrated in Figures 2 and 3; Figure 5 shows a schema-tic illustration of the inventive process during the production of a fibre layer; Figure 6 shows a plan view in the direction of arrow A in Figure 5; Figure 7 shows a perspective illustration of fibres deformed in their cross section and Figure 8 shows a schematic illustration of a segment of a structural element similar to Figure 1 and a laying out of a fibre layer according to a variation of the inventive process.

13 - An inventive structural element, designated as a whole as 10, extends along a line of curvature 12 which, in the case illustrated in Figure 1, extends in the plane of drawing. However, the line of curvature 12 can, in principle, extend in any optional manner in the space.

The structural element thereby has a first boundary 14 and a second boundary 16, both of which likewise extend in the same surface area as the line of curvature 12, wherein the line of curvature 12 is located between the two boundaries 14 and 16. The course of the line of curvature 12 between the two boundaries is preferably defined by the central points of all the imaginary geometrical spheres, represented in the illustrated, plane case by circles 18 which touch, on the one hand, the first boundary 14 and, on the other hand, the second boundary 16 and are located between them.

The geometrical circles 18 are also located in the same surface area, in which the line of curvature 12 and the boundaries 14 and 16 are located and which can, in principle, be a surface area extending in the space but in the case of Figure 1 coincides with the plane of drawing. The segment of an inventive structural element 10 illustrated in Figure 1 is thereby subject to transverse force components 20 which are directed transversely to the line of curvature 12 and likewise located in the surface area, in which the line of curvature 12 and the boundaries 14 and 16 extend.

Proceeding from this most general of definitions of a curved structural element 10, illustrated in Figure 1 as a structural element curved in one plane, an example of such a curved structural element 10 is a reinforcing ring 110 of a motor vehicle wheel rim 112, which is illustrated in Figure 2. As illustrated in Figure 3 in cross section, the motor vehicle wheel rim 112 comprises a hub 114 which extends around an axis of rotation 116 rotationally symmetric thereto and has an outer member 118 with a rim flange 119, into which the reinforcing ring 110 is inserted for its strengthening.

Such a motor vehicle wheel rim 112 is acted upon during daily use not only by essentially homogeneous forces of gravity directed in radial direction in relation to the axis of rotation 116 but possibly, for example when travelling over uneven ground, by transverse forces 120 which represent punctual loads.

If the reinforcing ring 110 is therefore wrapped as a fibre composite ring with fibres extending azimuthally to the axis of rotation 116 or in the form of a tangential circumferential wrapping, a shearing failure and thus breakage of it can take place due to the transverse forces 120 occurring since the fibres in fibre-reinforced structural elements exert no stabilising effect whatsoever in relation to shearing forces and, in addition, the risk of the fibres breaking exists when such shearing forces Cccur.

A segment of an inventive structural element 10 - for example, the reinforcing ring 110 - illustrated in Figure, is therefore produced from a fibre composite, wherein in this fibre composite fibre strand portions 22 and 24 extend in respective longitudinal directions 26 and 28 which, for their part, run transversely to the line of curvature 12. In this 1---1 --- - 15 respect, the fibre strand portions 22 and 24 form altogether a lattice structure which is suitable for absorbing transverse force components 20 and splits these transverse force components 20 into partial forces which can be absorbed by the fibre strand portions 22 and 24 extending in the directions 26 and 28.

Such a fibre composite illustrated in Figure 4 is built up of several fibre layers lying on top of one another, the production of a single fibre layer 30 being illustrated in Figure 5.

The finished structural element 10 is illustrated in Figure 5 shaded in grey so that the first boundary 14 and the second boundary 16 represent arcs of a circle in view of the fact that this is a circular structural element while the line of curvature 12 forms an arc of a circle illus-rated, centrallv, between the boundar ies 14 and 16, all these being located in surface area formed by the plane of drawing of Figure 5.

Outside the boundaries 14 and 16 of the finished structural element 10, outer deflecting pins 34 are arranged, for its production, on an outer circular arc 32 and inner deflecting pins 38 on an inner circular arc 36.

In Figure 6, the outer deflecting pins 34 are illustrated by dash-dot 11nes while the inner deflecting pins 38 are drawn as solid lines.

All the deflecting pins 34 and 38 ris,-- above a base surface 40 which represents a support surface for the lowest fibre layer 16 - in this case and in the present case is a plane surface area but can, in principle, be a surface area curved in the space (Figure 6).

The base surface 40 is thereby a surface of a carrier 42, on which the deflecting pins 34 and 38 are also preferably held.

The lowest fibre layer 30 is formed, for example, by a first fibre 50 which is illustrated as a solid line, extends with the fibre strand portion 221 transversely to the line of curvature 12 and forms with this a positive angle a,. The fibre strand portion 22,_ is followed by a closed loop 52, with which the fibre 50 winds around the outer deflecting pin 34a following the fibre strand portion 221 and, following this, then extends agaLn between the first boundary 14 and the second boundary 16 in the form of the fibre strand portion 241, the second fibre strand prt-- 'lon 241 forming a negative angle 01 with the line of curvature 12. In the simplest case, the angles cc, and 01 are of 'L:-he same size. However, the angles a, and 01 can, in principle, alsc be of different sizes.

The angles a, and P, are selected depending on size and direction of the expected transverse force components 20.

Following the fibre strand portion 241, the fibre 50 forms a C-shaped arc 54, with which this w-'nds around the inner deflecting pin 38a in a C shape, i.e. in the form of an unclosed loop, in order to then extend again between the second boundary 1.6 and the first boundary 14 through the structural element 10 which later results, thereby forming the fibre 17 - strand portion 221. This fibre strand portion 22 is again followed by a closed loop 52, with which it winds around the outer deflecting pin 34a.

1 Altogether, the fibre 50 thus forms in a direction 56 along the line of curvature 12 fibre strand portions 221 and 241 which are arranged to follow one another, the fibre strand portions 221 always forming the positive angle cc, with the line of curvature 12 and the fibre strand portions 241 the negative angle 01, and thus the fibre strand portions 221 and 241 represent, altogether, straight sections of a zigzag line.

In this respect, the deflecting pins 34a and 38a, which respectively deflect the first fibre 50, are located along the line of curvature in the direction 56 one after the other at predetermined distances, the distances between an outer deflecting pin 34a and the inner deflecting pin 38a, around which the fibre next winds, define the angle P, and the distances between an inner deflecting pin 38a and the next following, outer deflecting pin 34a, around which the fibre 50 winds, define the angle a-,.

In the embodiment illustrated in Figure 5, the deflecting pins 34a and 38a which respectively deflect the fibre 50 are arranged at constant angular distances in relation to a central point of the circular arcs 32 and 36, wherein the angular distances can, however, also vary in order to obtain varying angles a: and P- in relation to the line of curvature 12.

-, _ - 18 In principle, it is sufficient to form the fibre layer 30 by means of one fibre. However, in order to obtain as compact a structure of the structural element as possible, it is preferably provided for a second fibre 60 to extend in the fibre layer 30, this second fibre preferably extending at a distance next to the first fibre 50 and likewise having fibre strand portions 222 and 242. The fibre strand portions 222 of the second fibre 60 likewise form the positive angle a2 with the line of curvature 12 and the fibre strand portions 242 Of the second fibre 60 the negative angle 02 with the line of curvature 12. However, the angles a2 and 02 between the line of curvature 12 and the fibre strand portions 222 and 242 Of the second fibre 60 can, in principle, be completely different to the angles ct and 0 of the first fibre 50.

In order for the second fibre 60 to extend between the boundaries 14 and 16 of the structural el-ement 10 next to the first fibre 50 without crossing, the second fibre 60 preferably L J_ winds around the same outer deflecting pin 34a as the first fibre 50 but wit-h a C-shaped loop 64 while the second fibre 60 winds around the inner deflecting pin 38a with a closed loop 62 so that each of the fibres 50 and 60 winds around each of the outer deflecting pins 34a and the inner deflecting pins 38a. In this respect, one fibre 150 or 60 always winds around the deflecting pin 34a or 38a with a closed loop 52 or 62 and the other fibre 60 or 50 winds around the deflecting pin 34a or 38a with a non-closed, C-shaped loop 64 or 54.

In order to avoid crossing points 58 of the closed loops 52 and crossing points 68 of the closed loops 62 of the first fibre 50 and the second fibre 60, respectively, being located within the structural element 10 which later results, the deflecting pins 34 and 38 are arranged at such a distance from the boundaries 14 and 16 that 'the crossing points 58 and 68 which result are located outside these boundaries 14 and 16.

The fibre layer 30 illustrated in Figures 5 and 6 is followed by a next fibre layer, in which the first fibre 50 and the second fibre 60 are not, however, laid around the same deflecting pins 34a and 36a but around deflecting pins 34b and 38b arranged so as to be angularly offset in relation to them. This means that the fibre strand portions 22 and 24 of the next following fibre layer are arranged in the direction 56 at a distance in relation to the fibre strand portions 22 and 24 of the fibre layer 30 illustrated in Figures 5 and 6 and so the lattice structure illustrated in Figure 4 can be built up by laying severel fibre layers on top of one another, when the number of fibre layers located on top of one another and the number of deflecting pins 34 and 38 are increased and the angular offset between them is reduced.

The fibres 50 and 60 of each fibre layer can be individual filaments. However, fibre bundles consisting of a plurality of individual filaments are preferably used, the individual filaments being wetted with a hardenable substance, in the simplest case a resinous substance which, on the one hand, reinforces the fibre bundles or individual fibres or rovings themselves after its hardening but, on the other hand, also bonds all the fibre strand portions located on top of one another with one another so that the structure illustrated in Figure 4 forms an inherently rigid unit.

- After the hardenable substance has hardened, the boundaries 14 and 16 are produced by severing the parts of the fibres 50 and 60 located outside them, in particular the loops 52 and 54 or 62 and 64.

Particularly when using fibre bundles as fibres 50 and 60 of each fibre layer 30, the entirety of all the fibre strand portions 22 and 24 are pressed together, after producing the entirety of all the fibre layers andprior to the hardening of the hardenable substance, by means of a pressing force 70 preferably directed at right angles to the base surface 40. In this case, as illustrated in Figure 7, the fibres 50 and 60 do not have a round cross section but rather a cross section which is pressed flat and they are, therefore, broadened in the direction 56 so that when the fibre strand portions 22 and 24 in consecutive fibre layers are positioned sufficiently close to one another the lattice structure according to Figure 4 can be pressed to form, altogether, an all-over structure.

In order to create, in a variation of the inventive process, a structural element 10' which is illustrated generally in Figure 8 and which is capable of absorbing particular transverse forces 20', for example transverse force components 201 acting on both sides of a curvature 72, this provides for fibre strand portions 22 and 24 following one another in the direction 56 along the line of curvature 12 to always extend transversely to cross-sectional planes Q which are at right angles to the line of curvature 12 and for the consecutive fibre strand portions 22 and 24 to form with one another an angle y which is smaller than 180.

21 - Furthermore, it is possible with this variation to have individual fibre strand portions, for example the fibre strand portion 221t, running tangentially to the line of curvature 12 in order to create the possibility in the region of the curvature 72 of also absorbing longitudinal forces occurring in tangential direction, for example triggered by the transverse force components 201 acting on both sides of the curvature 72.

- 22

Claims

C L A I M

S Process for the production of a segment of a structural element extending along a line of curvature, said structural element being subject to forces acting thereon with transverse force components extending transversely to the line of curvature, characterized in that the structural element (10) is produced from a fibre composite, that the fibre composite results from laying out fibres (50, 60) in several fibre layers (30) located on top of one another, that in the segment at least one fibre layer (30) has fibre strand portions (22, 24) arranged to follow one another in the direction (56) along the line of curvature (12), said strand portions extending at an angle to the line of curvature (12), and that the fibre layers (30) extend in surface areas running parallel or at an acute angle to a plane defined by the line of curvature (12) and the respectively operative transverse force component- (20).

2. Process as defined in claim 1, characterized in that the fibre strand portions (22, 24) of a fibre layer (30) following one another in the direction (56) along the line of curvature (12) are laid out such that one of the fibre strand portions (22, 24) intersects the line of curvature (12) with a positive angle (a) and the next following portion intersects the line of curvature (12) with a negative angle (0) 3. Process as defined in claim 1 or 2, characterized in that the fibre strand portions (22, 24) extend along straight sections of a zigzag line, the points of reversal (34, 38) thereof being located on both sides of the line of curvature (12).

4. Process as defined in claim 3, characterized in that the line of curvature (12) extends in a central region located between the points of reversal (34, 38).

5. Process as defined in the preamble to claim 1 or as defined in any one of IC-he preceding claims, characterized in that the structural elements (10) are produced from a fibre composite, that the fibre composite results from laying out fibres (50, 60) in several consecutive fibre layers (30'), that in the segment at least one fibre!aver (30') of the fibre composite has fibre strand portions (22', 24') extending at an angle to cross-sectional areas (Q) extending at right angles to the line of curvature (12), and that the fibre layers (301) extend in surface areas running parallel or at an acute angle to a plane defined by the line of curvature (12) and the transverse force components (201).

Process as defined in claim 5, characterized in that the consecutive fibre strand portions (221, 24') form with one another an an-lle (y) smaller than 1800.

24 Process as defined in claim 5 or 6, characterized in that the fibre strand portions (22', 24') of this fibre layer (30) extend at least in partial sections thereof (22't) from one point of reversal located on one side of the line of curvature (12) to another point of reversal located on the same side of the line of curvature (12).

8.

Process as defined in any one of the preceding claims, characterized in that the fibre strand portions (22, 24) are laid out such that they extend without overlapping within each individual fibre layer (30) of the finished structural element (10).

9. Process as defined in any one of the preceding claims, characterized in that the fibre layers (30) laid one on top of the other are pressed to one another by a pressing procedure operative transversely to the surface area cfthe fibre layers (30).

10. Process as defined in any one of the preceding claims, characterized in that a fibre layer (30) is built up of groups of fibre strand portions (22, 24), and each group comprises several fibre strand portions (22, 24) extending next to one another.

11. Process as defined in any one of the preceding claims, characterized in that the individual fibre strand portions (22, 24) are sections of a continuously 'Laid out fibre (50, 60).

- 25 12. Process as defined in claim 11, characterized in that the individual fibre strand portions (22, 24) extend between two deflection points (34, 38) of the continuously laid out fibre (50, 60).

13. Process as defined in claim 11 or 12, characterized in that the fibres (50, 60) comprising the fibre strand portions (22, 24) of a group of two extending next to one another are deflected in the region of the same deflection points (34, 38).

14. Process as defined in claim 13, characterized in that one of the fibres (50, 60) forming the two fibre strand portions (22, 24) extending next to one ano-,her winds around the deflection point (38, 34) with an open loon (54, 64) and the other fibre (60, 50) winds around the deflection point (34, 38) with a closed loop (52, 62).

Process as defined in any one of claims 3 to 14, characterized in that the fibre (50, 60) is laid around a deflecting element (34, 38) in the region of each deflection point.

16. Process as defined in claim 15, characterized in that the fibre (50, 60) is laid around the deflectina elements 134, 38) with tension in the longitudinal direction of the fibre.

17. Process as defIned in either of claims 16 or 17, characterized in that each deflecting element (34, 38) forms a member rising above a,base surface (40) for a - 96 lowest fibre layer (30) 18. Process as defined in claim 17, characterized in that the deflecting element (34, 38) is of a pin-like design.

19. Process as defined in any one of the preceding claims, characterized in that the fibres (50, 60) of all the fibre layers (30) form a structure filling the segment of the structural element (10) over the entire surface area.

20. Process as defined in any one of claims 1 to 19, characterized in that the fibres (50, 60) of all the fibre layers (30) form a structure filling the segment of the structural element in a 'Latticed manner.

21. Process as defined in any one of the preceding claims, characterized in that the fibre strand -,)ortions (22, 24) of fibre lavers (30) arranged one above the other are arrang-d so as tu be o--5'-j-sei relative to one an,--,Eher in the ci-L'--ec'L-io:- along the 'Line of cur-,7a-.,--re (1.2,.

22. Process as defined in claim 21, characterized in that the fibre strand portions (22, 24) of two consecutive fibre lavers (30) corresponding to one another are arranged so as to be offset relative to one another by the same distance.

23. Process as defined in anv one of the preceding claims, characterized in that the---Eibres(50, 60) are individual filaments.

27 24. Process as defined in any one of claims 1 to 22, characterized in that the fibres (50, 60) are fibre bundles produced from individual filaments.

25. Process as defined in any one of the preceding claims, characterized in that the fibres (50, 60) are wetted with a hardening material during the production of the segment of the structural element (10).

26. Process as defined in any one of the preceding claims, characterized in that each fibre (50, 60) is laid oul- as a fibre wet-Led with the hardening material.

Process as defined in any one of the preceding claims, characterized in that the fibre strand portions (212, 24; a--e laid out by a manipulator.

28. Process as defined in claim 27, characte--i7-ed in that the stra-nd P, -)r-Lions (22, 24) a:e laid ouz cy a imovement f the maninulator laying out the fibre strand portions '22, 2) s,: as to extend from one point of reversal (34, 38) to the other point of reversal (34, 38).

Process as defined in claim 27 or 28, characterized in 7-hat the fibre strand -oortions (22, 24) are laid out individually.

30. Process as defined in claim 29, characterized in that the trand portions (22, manipulato.r cuts the individual fibre s,- 24) from a continuous fibre (50, 60).

28 - 31. Process as defined in claim 30, characterized in that the manipulator cuts the fibre each time after laying out one fibre strand portion (22, 24) and ahead of a point of reversal and following the point of reversal begins again with the laying out of the next fibre strand portion (22. 24).

32. Process as defined in either of claims 27 or 28, characterized in that the manipulator lays out the fibre strand portions (22, 24) in the form of a continuous fibre (50, 60).

33. Process as defined in claim 32, characterized in that the continuous fibre (50, 60) extends from paint of reversal to point of reversal.

34. A structural element having a segment produced according to a method as defined in any preceding claim.

35. A process for the production of a segment of a structural element substantially as herein described with reference to the accompanying drawings.

36. A structural element substantially as herein described with reference to the accompanying drawings.