DE102014116027A1 - Method for producing a fiber composite component and fiber composite component - Google Patents

Abstract

A method is proposed for producing a fiber composite component (10) which has at least one defined trigger point (28) for failure initiation in the event of an overload, in which a fiber structure (12) having one or more main directions (18; 22; 26) of a fiber path is positioned and at least one displacement element (30) is positioned at which fibers of the fiber structure (12) with respect to the main directions or (18; 22; 26) are deflected.

Description

The invention relates to a method for producing a fiber composite component, which has at least one defined trigger point for a failure initiation in the event of an overload.

The invention further relates to a fiber composite component.

For certain applications, it can be advantageous if a fiber composite component has a defined failure initiation, for example, to reduce acceleration loads on passengers in a passenger compartment in a crash load case or, for example, to purposefully generate a "good-natured" crash kinematics.

The invention has for its object to provide a method of the type mentioned, by means of which a fiber composite component can be produced, which has a high static load capacity outside the overload case.

This object is achieved according to the invention in the method mentioned above in that a fiber structure is positioned with one or more main directions of a fiber flow and at least one displacement element is positioned at which fibers of the fiber structure are deflected with respect to the main directions.

The deflection of the fibers in the vicinity of the at least one displacement element results in a spatially defined local weakening. In an overload case, crack initiation due to a local voltage increase by the fiber deflection can occur there and / or the bulge stability is reduced locally and / or a voltage increase due to a local jump in stiffness occurs.

Since the fibers are not severed in the vicinity of the displacer element, the static load capacity is substantially retained compared to the undisturbed area outside the surroundings of the displacer element. The "normal load capacity" of the fiber composite component thus produced is thus not significantly adversely affected. However, for the overload case and, for example, crash load case, a defined triggering can be achieved in order to generate, for example, a defined crash kinematics.

The defined trigger points can be produced in a simple manner via at least one displacement element.

In particular, the fiber structure comprises endless fibers.

The fiber structure in the fiber composite component is favorably influenced by the at least one displacement element such that crack initiation occurs in an overload due to a local voltage increase due to fiber deflection and / or buckling stability is locally reduced and / or a voltage increase occurs due to a local jump in stiffness. It can thereby achieve a targeted failure initiation in an overload case and, for example, crash without significant deterioration of the static load capacity.

In particular, a change in the course of fibers with respect to the main direction (s) is produced by the at least one displacement element without interruption of the fibers. As a result, a defined weakening can be installed locally, but this does not significantly impair the static load-bearing capacity.

It is also possible that a fiber spacing in the vicinity of the at least one displacement element is reduced by the at least one displacement element. As a result, for example, in the case of overload, a local jump in stiffness can be achieved, which is due to the increased strength due to the reduced fiber spacing. This in turn can lead to a voltage overshoot and to a defined failure initiation at such a location.

In the manufacture, in particular fibers of the fiber structure are applied for deflection to the at least one displacement element and / or are placed following an outer contour of the at least one displacement element. As a result, a defined trigger point for the failure initiation in case of overload can be established.

In one embodiment, the at least one displacement element at least in a partial region has a curved and / or rounded outer contour and in particular an edge-free outer contour. This allows a defined deflection can be achieved without the risk of fiber separation is present. Basically, the shape of the displacer element (geometric shape and size) is a parameter for the mode of failure initiation.

For example, the at least one displacement element has a circular or oval or lenticular shape in cross section. As a result, a diversion can be achieved in a simple manner.

The at least one displacement element is made of plastic or metal, for example.

In one embodiment, the at least one displacement element remains after the fiber structure laying in the fiber composite component. The displacer is therefore not removed.

The at least one displacement element can then have at least one additional function as an insert, wherein the additional function, for example, an introduction of force, a force discharge, a holding, a line function (for fluids and / or electrical current and / or optical signals, etc.), a sensor function, a fastening function , an assembly function, etc. may be.

For example, the at least one displacement element is designed as part of a ventilation device for ventilating the component.

It is also possible, for example, for the at least one displacement element to be designed as an inspection opening or as part of an inspection opening.

In principle, the at least one displacement element can also be used to facilitate resin infiltration of the fiber structure. The at least one displacement element is then formed as part of a Harzinfiltrationseinrichtung.

It can also be provided that the at least one displacement element is removed after the deposition of the fiber structure and in particular is removed when a defined fiber deflection is achieved in the vicinity of the displacement element. The place where previously was the displacer can then be filled with resin, for example, or remain as a "hole" or cavity.

In particular, after deposition of the fiber structure, a resin infiltration and / or the fiber structure is impregnated with resin. After curing of the resin, a fiber composite component is then produced as a composite component (CFRP component).

The fiber structure is in particular a knit fabric and / or woven fabric and / or a braid and / or a scrim or has such. As a result, optimized structural properties can be obtained.

It is advantageous if, in a region adjacent to the at least one displacement element, a material which is viscous with regard to crack propagation is positioned. The corresponding area is purposefully consolidated or modified with the tough material in order to inhibit crack propagation. It can thereby better preserve the structural integrity of the fiber composite component which is manufactured accordingly. Tough crack propagation in this adjacent area can increase absorbed energy in an overload condition. The tough material has a higher toughness with respect to crack propagation than the fiber composite outside of this range. The tough material is for example an aramid plastic or a metal (with plastic deformability).

In particular, the material which is tough with respect to the crack propagation has an elongation at break greater than the breaking elongation of the fiber composite material outside the region with the viscous material. This gives a higher energy absorption, which causes a "tougher" crack propagation and thereby inhibits crack propagation.

In particular, the material which is tough with respect to the crack propagation has an elongation at break greater than 1% and in particular greater than 1.5% and in particular greater than 2%. Elongation at break is the yield strength at which material breakage occurs with one or more cracks. By the adjacent area around the at least one displacement element with increased elongation at break, the crack progress is inhibited.

In particular, a fiber composite component is produced according to the method of the invention.

A fiber composite component according to the invention comprises a fiber structure with one or more main directions for a fiber path and at least one defined trigger point for a failure initiation in case of overload, wherein at the at least one trigger point there is a fiber deflection with respect to the main direction (s) without fiber interruption.

The fiber composite component according to the invention has the advantages already explained in connection with the method according to the invention.

In one embodiment, at least one displacement element for fibers is or was arranged at the at least one trigger point. As a result, a defined deflection can be achieved.

The at least one displacement element may have at least one additional function as an insert, wherein the additional function may include: forming the at least one displacement element for force introduction, force discharge, as a holder, as a line (for fluids, electrical current, signals, etc.), as a sensor, as a fastener , as a mounting element, as part of a ventilation device, as an inspection opening or part of an inspection opening, as part of a Harzinfiltrationseinrichtung.

The fibrous structure may be or include a knit fabric (such as a knit fabric) and / or a woven fabric (such as a fabric) and / or a braid and / or a scrim.

It is favorable if, in a region adjoining the at least one trigger point, a material which is viscous with regard to crack propagation is positioned. This material inhibits crack propagation and increases absorbable energy. As a result, a structural integrity of the fiber composite component can be better ensured in case of overload.

In particular, the material which is tough with respect to the crack propagation has an elongation at break greater than the breaking elongation of the fiber composite material outside the region with the viscous material. This results in an inhibition of crack propagation compared to the case where the tough material is absent.

In particular, the material which is tough with respect to the crack propagation has an elongation at break greater than 1% and in particular greater than 1.5% and in particular greater than 2%. This provides increased energy absorption capacity to inhibit crack propagation.

According to the invention, the method mentioned at the outset or a fiber composite component according to the invention can be used for a vehicle (land vehicle, watercraft, aircraft, spacecraft), with a design in particular for a crash case being an overload case. For example, one or more fiber composite components according to the invention are used to form a passenger compartment of a vehicle. In a crash, a corresponding protection for passengers in the passenger compartment can then be achieved by a defined arrangement and design of the trigger points.

For example, the fiber composite component is designed as a bulkhead.

The following description of preferred embodiments is used in conjunction with the drawings for further explanation of the invention. Show it:

1 a schematic representation of an embodiment of a fiber composite component according to the invention in sectional view; and

2 a schematic representation of another embodiment of a fiber composite component according to the invention in a sectional view.

An embodiment of a fiber composite component according to the invention, which in a schematic sectional view in 1 shown schematically and there with 10 is designated comprises a fiber structure 12 made of continuous fibers.

This fiber structure 12 is in one embodiment with a resin 14 impregnated. The resulting fiber composite component 10 is a composite component (CFRP component), which is just a fraction of hardened resin 14 and the fiber structure 12 having.

The fiber structure 12 has one or more main directions. In the embodiment according to 1 includes the fiber structure 12 fibers 16 which are in a first main direction 18 are oriented. It also includes fibers 20 which are in a second main direction 22 are oriented.

The first main direction 18 and the second main direction 22 lie across each other.

Furthermore, the fiber structure comprises 12 fibers 24 which are in a third main direction 26 are oriented. The third main direction 26 is transverse to the first main direction 18 and transverse to the second main direction 22 ,

The fiber structure 12 may be a textile fabric, such as a knit fabric (such as a knit fabric) or woven fabric (such as a fabric). Depending on the application, the fiber structure 12 also be a braid or include or comprise a scrim.

For the production of the fiber composite component 10 First, the fibers of the fiber structure 12 placed. There is then a resin infiltration. In principle, in the fiber fabric, the fiber structure may already be preimpregnated with resin.

The fibers 16 . 20 . 24 the fiber structure 12 are in particular designed as rovings (bundles of individual fiber filaments).

After the resin infiltration or in the case of preimpregnated fiber structures after the fiber has been laid, the resin is cured.

Optionally, then a mechanical post-processing such as grinding, etc., to produce the final fiber composite component.

According to the invention, in the production of the fiber composite component 10 the fiber orientation specifically affects trigger points 28 , which are spatially defined, for a Failure initiation in an overload case and in particular crash case produce.

The trigger points 28 be by targeted deflection of fibers of the fiber structure 12 produced, wherein the fiber flow is not interrupted, that is at the trigger points 28 are fibers of the fiber structure 12 continuing throughout. This allows the fibers "normal" loads also at trigger points 28 take up.

In the production of the fiber composite component and in particular before the resin infiltration is (at least) a displacement element 30 positioned. The displacer element 30 steers in the environment 32 of the displacement element 30 Fibers in relation to the main directions 18 . 22 . 26 around. This diversion is in 1 by the reference numeral 34 indicated. The displacer element 30 So changes the fiber flow with respect to the direction in the environment 32 , wherein also a distance between fiber layers can change and in particular can decrease.

The displacer element 30 is positioned, for example during fiber laying.

The displacer element 30 is braided with deflected fibers, for example.

In one embodiment, the displacer becomes 30 in the process again after reaching the deflection 34 away. For example, the displacer element 30 during resin infiltration removes when the diversion 34 is enough "stable".

In another embodiment, the displacer remains 30 in the fiber composite component 10 that means it will not be removed.

The displacer element 30 is for example made of a plastic material or metallic material.

When the displacer element 30 remains in the fiber composite component, it can take on additional functions. It then forms an insert. It can be used, for example, to initiate forces, to divert forces, it can be used as a holder (for example, for sensors or actuators), it can have a conductive function for fluids, electrical current, optical signals, etc., it can have a sensor function, it can have a fixing function or have a mounting function. The displacer element 30 may be part of a ventilation device for the fiber composite component 10 be. It can serve as an inspection opening or be part of an inspection opening.

The displacer element 30 can also during the manufacture of the fiber composite component 10 to serve for resin infiltration and in particular to be part of a resin infiltration device.

It is basically possible that during the manufacture of the fiber composite component 10 several displacement elements 30 be used, with only a part of these displacement elements 30 is removed again.

In one embodiment, a displacer element 30 a curved or rounded outer contour 36 on. In particular, the outer contour is edge-free. Fibers for deflection at the displacer element 30 are applied to this or the fiber flow in the environment 32 follows the outer contour 36 of the displacement element 30 ,

In cross-section is a displacement element 30 for example, circular, oval or lenticular. Other shapes are possible depending on the application.

By the position of the displacement element 30 in the manufacture of the fiber composite component 10 is at a defined position in the component 10 generates a trigger point.

In "normal operation" of the fiber composite component 10 takes over the fiber structure 12 also in the environment 32 of the displacement element 30 the normal functions of fibers. Because the fibers in the environment 32 are not severed, although a weakening (see below), but the first comes to bear in the event of overload. Outside the overload case, fibers are also used in the environment 32 of the displacement element 30 for load transfer, as they are not interrupted.

The displacer element 30 or that region in which the displacement element 30 was positioned during manufacture, basically weakening the fibers of the fiber structure 12 wrapped around and wrapped, for example. The weakening is defined locally and it is a trigger point 28 provided. This trigger point 28 has a relatively high static load capacity, as at least approximately outside the environment 32 is present.

The diversion in the environment 32 causes crack initiation in case of overload due to local voltage overshoots. These local stress peaks are due to the deflection of fibers with respect to the main directions 18 . 22 . 26 causes. It takes place at the environment 32 a local reduced strength due to the fiber deflection. Furthermore, in the environment 32 locally a reduction of the bulge stability, so that a targeted buckling failure is present. Furthermore, local to the environment 32 a voltage increase due to a local jump in stiffness take place, wherein the jump in stiffness due to increased strength in the environment 32 the trigger site 28 due to increased fiber deposition (reduced distance from fiber layers) is achieved.

Due to the shape of the deflection, it is possible to set a failure force in accordance with a requirement profile during the production of the fiber composite component. By appropriate braiding (in particular two-dimensional) can be at the displacer 30 achieve the desired deflection.

Through the defined provision of trigger points 28 on the fiber composite component 10 For example, acceleration loads may be applied to passengers in a passenger compartment, which may consist of one or more components 10 is produced, can be lowered in a crash load case or it can produce a good-natured crash kinematics targeted.

A corresponding fiber composite component 10 will be used in particular for a vehicle (land vehicle, aircraft, spacecraft, watercraft, etc.). For example, a bulkhead of such a fiber composite component 10 or more of such components. For example, a passenger compartment is manufactured by means of such components.

The fiber composite component 10 has outside of the environment 32 an undisturbed fiber composite area. In the environment 32 of the displacement element 30 there is a weakening due to the deflection. In the component 10 can thereby the displacer 30 be positioned or there may be a hole or it may, for example, where the displacer 30 There was a resin collection available. By providing the displacement element 30 is a defined trigger point without significant deterioration of the static load capacity, as no fibers are severed 28 prepared for failure initiation in case of overload.

Also the special shape of the outer contour 36 a displacement element 30 is a parameter related to setting failure initiation.

In a further embodiment ( 2 ), wherein for like elements the same reference numerals as in the embodiment according to 1 is used in an area 38 , which to the environment 32 a displacement element 30 adjacent or adjacent to a trigger point in the manufactured component, a tough material 40 arranged. The material 40 is tough in terms of crack propagation. It is outside this range compared to the fiber composite 38 (For example, to the fiber composite material in the component according to 1 ) increased toughness with respect to crack propagation. This increased toughness inhibits crack propagation. It can be absorbed a higher energy, which the crack propagation (in 2 with the reference number 42 indicated) inhibits.

The tough material is selected to have an elongation at break greater than 1%, and more preferably greater than 1.5%, and most preferably greater than 2%. Elongation at break is the ductility at which a break occurs with one or more cracks. The breaking elongation of the material 40 is greater than the breaking elongation of the fiber composite outside of the range 38 ,

An area 38 So then has an increased energy absorption due to tough crack propagation. As a result, under certain circumstances, the structural integrity can also be maintained or better maintained in the event of an overload.

The material 40 is for example a plastic material or a metallic material. Metallic materials usually have an increased elongation at break due to their plastic properties. One possible plastic material is, for example, an aramid plastic.

The one to the environment 32 adjacent area surrounds in particular the trigger point on all sides to a crack propagation in all spatial directions, starting from the corresponding trigger point 28 to inhibit.

Otherwise, the fiber composite component works according to 2 in the same way as described above. In particular, the displacer element may also have been removed during the production of the component.

LIST OF REFERENCE NUMBERS

10

 Fiber composite material component

12

 fiber structure

14

 resin

16

 fibers

18

 First main direction

20

 fibers

22

 Second main direction

24

 fibers

26

 Third main direction

28

 trigger point

30

 displacement

32

 environment

34

 redirection

36

 outer contour

38

 Area

40

 material

42

 Crack Growth

Claims (28)

Method for producing a fiber composite component ( 10 ), which has at least one defined trigger point ( 28 ) for a failure initiation in an overload case where a fiber structure ( 12 ) with one or more main directions ( 18 ; 22 ; 26 ) of a fiber flow is positioned and at least one displacement element ( 30 ) on which fibers of the fiber structure ( 12 ) with regard to the main direction (s) ( 18 ; 22 ; 26 ) are redirected. Method according to claim 1, characterized in that the fiber structure ( 12 ) in the fiber composite component ( 10 ) by the at least one displacement element ( 30 ) is influenced so that in an overload, a crack initiation due to a local voltage increase by fiber deflection takes place and / or bulge stability is locally reduced, and / or a voltage overshoot occurs due to a local jump in stiffness. Method according to claim 1 or 2, characterized in that by the at least one displacement element ( 30 ) a change in the course of fibers with respect to the main direction (s) ( 18 ; 22 ; 26 ) is produced without interruption of the fibers. Method according to one of the preceding claims, characterized in that by the at least one displacement element ( 30 ) a fiber distance in the environment ( 32 ) of the at least one displacement element ( 30 ) is reduced. Method according to one of the preceding claims, characterized in that fibers of the fiber structure ( 12 ) for deflection to the at least one displacement element ( 30 ) and / or an outer contour ( 34 ) of the at least one displacement element ( 30 ). Method according to one of the preceding claims, characterized in that the at least one displacement element ( 30 ) at least in a partial area a curved and / or rounded outer contour ( 34 ) and in particular an edge-free outer contour ( 34 ) having. Method according to one of the preceding claims, characterized in that the at least one displacement element ( 30 ) has a circular or oval or lenticular shape in cross-section. Method according to one of the preceding claims, characterized in that the at least one displacement element ( 30 ) is made of plastic or metal. Method according to one of the preceding claims, characterized in that the at least one displacement element ( 30 ) after laying the fiber structure in the fiber composite component ( 10 ) remains. Method according to claim 9, characterized in that the at least one displacement element ( 30 ) as an insert has at least one additional function, wherein the additional function may include: a force application, a force discharge, a holding, a line function, a sensor function, a fastening function, a mounting function. Method according to claim 9 or 10, characterized in that the at least one displacement element ( 30 ) is formed as part of a ventilation device. Method according to one of claims 9 to 11, characterized in that the at least one displacement element ( 30 ) is formed as an inspection opening or part of an inspection opening. Method according to one of claims 9 to 12, characterized in that the at least one displacement element ( 30 ) is formed as part of a Harzinfiltrationseinrichtung. Method according to one of the preceding claims, characterized in that the at least one displacement element ( 30 ) after the filing of the fiber structure ( 12 ) Will get removed. Method according to one of the preceding claims, characterized in that after deposition of the fiber structure ( 12 ) a resin infiltration takes place and / or the fiber structure ( 12 ) is impregnated with resin. Method according to one of the preceding claims, characterized in that the fiber structure ( 12 ) is or has a knitwear and / or woven fabric and / or a braid and / or a scrim. Method according to one of the preceding claims, characterized in that in one of the at least one displacement element ( 30 ) adjacent area ( 38 ) a material that is tough with respect to crack propagation ( 40 ) is positioned. Method according to claim 17, characterized in that the material which is tough with respect to crack propagation ( 40 ) an elongation at break greater than the breaking elongation of the fiber composite material outside the zone with the tough material ( 40 ) having. A method according to claim 17 or 18, characterized in that the crack propagation material ( 40 ) has an elongation at break greater than 1% and in particular greater than 1.5% and in particular greater than 2%. Fiber composite component, which is produced in particular by the method according to one of the preceding claims, comprising a fiber structure ( 12 ) with one or more main directions ( 18 ; 22 ; 26 ) for a fiber course and at least one defined trigger point ( 28 ) for a failure initiation in an overload case, wherein at the at least one trigger point ( 28 ) a fiber deflection with respect to the main direction or directions ( 18 ; 22 ; 26 ) is present without fiber interruption. Fiber composite component according to claim 20, characterized in that at the at least one trigger point ( 28 ) at least one displacement element ( 30 ) is or was arranged for fibers. Fiber composite component according to claim 21, characterized in that the at least one displacement element ( 30 ) has as insert at least one additional function, wherein the additional function may include: forming the at least one displacement element ( 30 ) for force introduction, force discharge, as a holder, as a conduit, as a sensor, as a fastener, as a mounting element, as part of a ventilation device, as an inspection opening or part of an inspection opening, as part of a Harzinfiltrationseinrichtung. Fiber composite component according to one of claims 20 to 22, characterized in that the fiber structure ( 12 ) is or comprises a knitwear and / or a woven fabric and / or a braid and / or a scrim. Fiber composite component according to one of claims 20 to 23, characterized in that in one of the at least one trigger point ( 28 ) adjacent area a material which is tough with respect to crack propagation ( 40 ) is positioned. Fiber composite component according to claim 24, characterized in that the material which is tough with respect to crack propagation ( 40 ) an elongation at break greater than the breaking elongation of the fiber composite material outside the zone with the tough material ( 40 ) having. Fiber composite component according to claim 24 or 25, characterized in that the crack propagation material ( 40 ) has an elongation at break greater than 1% and in particular greater than 1.5% and in particular greater than 2%. Use of the method according to one of claims 1 to 19 or the fiber composite component according to one of claims 20 to 26 for a vehicle, wherein in particular a design for a crash occurs as an overload case. Use according to claim 27, characterized in that the fiber composite component is designed as a frame.

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