Fiber Composite Body and Method for Producing a Fiber Composite Body

Abstract

A fiber composite body, in particular a structure stiffening element, has a number of struts which are formed by reinforcing fibers which are embedded in a polymer matrix and which in a region of the respective strut run substantially parallel to one another. The struts are arranged in a truss-like profiled structure which is produced by winding or intertwining the reinforcing fibers.

Claims

1.-11. (canceled)

12. A fiber composite body, comprising a plurality of struts, wherein the plurality of struts are formed by reinforcing fibers which are embedded in a plastic matrix and which run substantially parallel to one another in a region of a respective strut; wherein the plurality of struts are arranged in a trusslike profile structure which is formed by wrapping or stitching the reinforcing fibers.

13. The fiber composite body according to claim 12, wherein the trusslike profile structure is formed by wrapping the reinforcing fibers and then pressing the wrapped reinforcing fibers.

14. The fiber composite body according to claim 12, wherein an entirety of the trusslike profile structure is formed by the reinforcing fibers.

15. The fiber composite body according to claim 12, wherein the reinforcing fibers are endless fibers and wherein at least a fraction of each of the endless fibers extends over respective adjacent struts of the plurality of struts.

16. The fiber composite body according to claim 12, wherein, in a transition region between a first strut and a second strut of the plurality of struts, at least one fraction of the reinforcing fibers leaves a bundle orientation of the first strut and transitions into a fiber reinforcement of the second strut.

17. The fiber composite body according to claim 12, wherein a respective connecting point is provided between interconnecting struts of the plurality of struts and wherein at the connecting point the respective reinforcing fibers of the interconnecting struts are formed as respective reinforcing fiber bundles that penetrate one another.

18. The fiber composite body according to claim 12 further comprising an attachment region for fastening the fiber composite body to a part, wherein the attachment region has a fastening element around which the reinforcing fibers extend.

19. The fiber composite body according to claim 18, wherein the fastening element has a fastening opening which is surrounded by an insert and wherein the reinforcing fibers are guided around the insert.

20. The fiber composite body according to claim 19, wherein the insert has an integrally formed plate.

21. The fiber composite body according to claim 18, wherein, in a transition region between one of the plurality of struts and the attachment region, a first fraction of the reinforcing fibers is crossed with second fraction of the reinforcing fibers.

22. A method for producing a fiber composite body, comprising the steps of: a) providing preimpregnated endless reinforcing fibers; b) wrapping the preimpregnated endless reinforcing fibers or stitching the preimpregnated endless reinforcing fibers to a carrier material to form a trusslike profile structure with a plurality of struts, wherein each of the plurality of struts is formed by the preimpregnated endless reinforcing fibers which run substantially parallel to one another in a region of a respective strut; c) inserting the wrapped or stitched preimpregnated endless reinforcing fibers into a compression mold; and d) compressing the inserted wrapped or stitched preimpregnated endless reinforcing fibers to form the fiber composite body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows a schematic illustration of a profile structure of a fiber composite body according to a first embodiment of the invention;

[0021] FIG. 2 shows an illustration of the orientation of the reinforcing fibers in a subregion of the fiber composite body from FIG. 1;

[0022] FIG. 3 shows a side view of the reinforcing fiber orientation in a fiber composite body according to a second embodiment of the invention;

[0023] FIG. 4 shows a side view of a fiber composite body according to a third embodiment of the invention;

[0024] FIG. 5 shows a side view of a fiber composite body according to a fourth embodiment of the invention, and

[0025] FIG. 6 shows a side view of a further embodiment of the invention with a stitched reinforcing insert.

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] FIGS. 1 and 2 show a fiber composite body 10 according to the invention in the form of a structure-stiffening element which serves in particular for stiffening the body of a motor vehicle.

[0027] The fiber composite body 10, which is of flat configuration here and extends substantially in two dimensions, namely in the drawing plane, has a plurality of struts 12 which are arranged in a trusslike profile structure 14. As can be seen from FIG. 2, the struts 12 are formed by reinforcing fibers 18 which are embedded in a plastic matrix 16 and which for the most part run parallel to one another in the region of the respective strut 12.

[0028] It should be pointed out that, in the course of this application, a strut is to be understood as meaning any individual rectilinearly running portion of the profile structure 14, that is to say not only the longer portions arranged along the main load directions, but also the shorter “braces” arranged therebetween, which are also referred to as transverse braces because they extend transversely with respect to the main load directions.

[0029] Here, the entire trusslike profile structure 14 is created by reinforcing fibers 18 which are embedded in the plastic matrix 16 in that the reinforcing fibers 18 preimpregnated with the matrix material are directly wrapped and then compressed. The reinforcing fibers 18 are endless fibers of which at least one fraction extends over a plurality of struts 12, for example 12a and 12b, 12a and 12c, 12e and 12g, 12e and 12f, 12b and 12f. It is even conceivable that the entire structure is wrapped from a single endless fiber bundle.

[0030] Transition regions 20, also referred to as nodes, are provided between in each case two (or more) struts 12 (for example 12a, 12b and 12c, 12e, 12f, 12g and 12b, etc., in FIG. 2), wherein, in a transition region 20, at least one fraction of the reinforcing fibers 18 leaves the bundle orientation of the one strut (for example 12a) and transitions into the fiber reinforcement of the other strut (for example 12b). In particular, bundles of struts which run in the main load direction (struts on the outside) run into transverse struts.

[0031] Furthermore, the fiber composite body 10 has a plurality of attachment regions 22 for fastening the fiber composite body 10 to a neighboring part (not shown), wherein the attachment regions 22 each have a fastening element 24 around which the reinforcing fibers 18 extend. Each fastening element 24 comprises a fastening opening 26 which is surrounded by a sleeve 28 which forms part of an insert 30 around which the reinforcing fibers 18 are guided. In the example shown, the inserts 30 are made of metal; alternatively, inserts 30 made of plastic are also possible.

[0032] In order to securely anchor the inserts 30 in the fiber composite body 10, each insert 30 has an anchoring means in the form of an integrally formed plate, which in FIG. 2 extends substantially parallel to the drawing plane between a plurality of layers of reinforcing fibers 18, but is not illustrated in the Figure.

[0033] In addition, each insert 30 has one or more pinlike extensions 32 which are connected to the plate at a distance from the sleeve 28, wherein a fraction of the reinforcing fibers 18 belonging to the respective strut 12 is crossed with another fraction of the reinforcing fibers 18 between the respective extension 32 and the sleeve 28. This achieves a particularly high stability of the fiber composite body 10 precisely in the transition regions 33 between the struts 12 and the attachment regions 22. In particular, the struts 12 or the entire profile structure 14 can be loaded not only in tension but also very well in compression.

[0034] To manufacture the fiber composite body 10, first of all preimpregnated endless reinforcing fibers are provided which are then wrapped according to a specific wrapping plan to form the trusslike profile structure 14, for instance in a wrapping tool. Here, each individual strut 12 of the profile structure 14 is formed by a plurality (a bundle) of reinforcing fibers 18 running parallel to one another. Here, the inserts 30 can serve as winding aids and are enwrapped concomitantly directly with the wrapping of the profile structure 14. Finally, the wrapped reinforcing fibers 18 (together with inserts 30) are inserted into a compression mold and compressed to form the finished fiber composite body 10, wherein the inserts 30 are connected to the remainder of the fiber composite body 10 in a form-fitting and/or integrally bonded manner (the latter in the case of plastic inserts). An encapsulation of the reinforcing fibers 18 by injection-molding does not take place in the method according to the invention.

[0035] FIG. 3 shows a detail view of the orientation of the reinforcing fibers 18 in a fiber composite body 10 in a slightly modified embodiment. There can be seen particularly clearly here the transition regions 20 in each of which a fraction of the reinforcing fibers 18 leaves a bundle orientation of the one strut 12 and transitions into the fiber reinforcement of another strut 12.

[0036] A further fiber composite body 10 which differs only slightly from that of FIGS. 1 and 2 is shown in FIG. 4. Here, the trusslike profile structure 14 has more short struts 12 which extend between the long struts 12 arranged along the main load directions, which has a positive effect on the stability of the fiber composite body 10.

[0037] A further embodiment of a fiber composite body 10 according to the invention is shown in FIG. 5, with it also being the case here that identical components bear the same reference signs and only the differences from the previously described embodiments will be discussed.

[0038] In the fiber composite body 10 according to FIG. 5, a plurality of struts (for example 12a and 12b, 12c and 12d, etc.) intersect directly, with connection points 34 at which the reinforcing fibers 18 intersect being provided between the intersecting struts 12. In particular, the reinforcing fibers 18 of each strut 12 form a reinforcing fiber bundle, and the reinforcing fiber bundles of two struts 12 penetrate one another at the connection points 34. Here, one bundle can be guided centrally through the other, or both bundles are divided into a plurality of layers which intersect in alternating fashion.

[0039] The preimpregnated reinforcing fibers 18 can be compressed with one another somewhat more at the connection points 34 (or “nodes”) than in the central regions of the struts 12, as a result of which flat connection points 34 and a particularly high stability can be achieved. It is of course also possible for the fiber composite body 10 according to FIG. 5 to have a plurality of attachment regions with fastening openings, although these are not shown here.

[0040] A further embodiment of the invention is provided in FIG. 6. Here, a carrier material 50 composed of a glass fiber textile or a carbon fiber textile is embroidered by means of reinforcing fibers 18, as have already been mentioned above. The carrier material 50 can be a nonwoven, for example. The carrier material 50 is cut off for embroidering (for example by punching, cutting, including laser cutting) in such a way that clearances 52 and struts 12 are produced. Between the struts 12 there can also be connection points 34 here in which the density of the reinforcing fibers 18 is higher. The increased density can occur by repeatedly embroidering or stitching patterns or the like. The reinforcing fibers 18 can be preimpregnated or else not. If they are not preimpregnated, the flat basic shape, as is illustrated in FIG. 6, is embedded in a plastic matrix and compressed in a mold. Excess carrier material 50 can be removed by a machining method or by laser cutting. Alternatively, the carrier material can be in the form of a strip which is then embroidered. The strip is then wrapped, for example as is shown in FIGS. 1 to 5.