DE102007062082A1 - Core composite, particularly for use in aerospace area, has upper cover layer, lower cover layer and core element arranged between cover layers, where core element is formed as honeycomb structure - Google Patents

Abstract

The core composite has an upper cover layer (9), a lower cover layer (10) and a core element (1) arranged between the cover layers. The core element is formed as honeycomb structure, where the cover layers have a carbon furnish layer (2,3,4,5) facing the core element and a fiber glass layer (6,7,8) turned away from the core element.

Description

The The present invention relates to a core composite structure a core element and cover layers with carbon fiber and glass fiber layers.

Even though Applicable to any range, the present invention as well as the underlying problems with regard to air and gas Space travel closer explained.

In aircraft construction, identical structures are currently used at Oberdecks for both cargo and passenger aircraft. These composite structures have a core element, on the top and bottom of each a cover layer of fiber layers is applied. The Anmelderen are core elements with a honeycomb structure with an aramid fiber, for example a Nomex ^® -Wabe known. On both sides of the core element there may be a variable number of fiber layers. These fiber layers may differ in their resin content, the type of resin used, and the type of glass fiber used. To build up the systems, prepreg glass fiber materials are commonly used.

adversely the use of glass fibers as fiber reinforcements for a core element is high Weight of glass fiber reinforcements. Especially in the aerospace sector, however, is the weight an important factor.

It is therefore an object of the present invention, a weight-reduced To provide core composite structure. Another task of the present Invention is a core composite structure with increased bending stiffness and impact resistance provide.

According to the invention this Task by a core composite structure with the features of the claim 1 solved.

Accordingly, a Core composite structure with upper and lower cover layers and a core element disposed between the cover layers, which is formed as a honeycomb structure provided, wherein the cover layers each on the core element facing side, d. H. core element side, at least one carbon fiber layer and on the core element opposite side, d. H. core composite structure on the outside, at least one Have fiberglass layer.

The The idea underlying the present invention is that that by using carbon fiber layers instead of fiberglass layers in the interior of the core composite structure a weight reduction at the same time increased Flexural strength and impact resistance or shock resistance achieved can be.

In the dependent claims find advantageous embodiments and improvements of Invention.

According to one preferred development, the honeycomb structure has an aramid fiber on.

aramid are characterized by very high strength, high impact strength, high elongation at break, good vibration damping and durability across from acids and alkalis. They are above In addition, very heat and fire resistant. Aramid fibers do not melt at high temperatures, but begin from about 400 ° C to char.

According to one Particularly preferred development is the honeycomb structure of a Aramid fiber paper constructed. For example, the aramid fiber paper by means of usual Paper manufacturing process are formed. Particularly preferred the honeycomb structure of a paper with meta-aramid fibers and / or composed of a paper with a mixture of meta-aramid fibers and para-aramid fibers.

Commercially such aramid papers are known, for example as Nomex ^® -paper. This paper may be soaked or coated with a synthetic resin, such as an epoxy or phenolic resin, to further enhance stability and prevent liquid ingestion of the paper. Aramid fiber paper made from meta-aramid fibers is less penetrated by a synthetic resin than a paper made from a mixture of meta-aramid fibers and para-aramid fibers. The meta-aramid fiber paper is therefore coated in the form of a lacquer. If the synthetic resin penetrates the fiber paper, a lighter structure compared to only coated papers with the same stability can be produced.

According to one another preferred embodiment of the present invention has the honeycomb structure has a hexagonal structure or an approximately hexagonal one Structure on.

By the use of hexagonal honeycomb structures, also called honeycombs can be called high mechanical strength at the same time low weight can be achieved.

In accordance with yet another preferred development of the present invention, at least two coals are present in one or both cover layers fabric fiber layers included. Preferably, these layers directly adjoin one another.

The Carbon fibers are oriented within a layer. there Preferably, the fibers within a layer are in one direction. If there are several different carbon fiber layers, show Here are the orientations of the carbon fibers in the different Strata particularly preferably has different directions. In a particularly preferred development in this case have the carbon fibers in different directions and form an angle between the fibers of 80 ° -100 °, in particular preferably an angle of about 90 °, between the different ones Layers. However, it is also possible that the carbon fibers include other angles. Prefers are also angles between 40 ° and 50 °, in particular about 45 °.

Become more than two carbon fiber layers in one or both layers introduced, can the carbon fibers contained in the layers differ Include angle. For example, has the first carbon fiber layer in one direction from 0 °, For example, parallel to the fuselage of an aircraft, so can the orientation the fibers in another carbon fiber layer in one direction of 45 °, in a direction of 90 ° and / or in a direction of 135 ° with respect to the fibers of the first carbon fiber layer.

Become the carbon fiber layers oriented in different directions, can the forces occurring deliberately transmitted become. It is thus possible to design the composite structure such that the carbon fiber layers in the directions of the main ones power transmission are oriented.

According to one Another preferred embodiment of the present invention the carbon fibers in the carbon fiber layers scrim.

The Clutch can advantageously be formed from prepreg carbon fibers. By the Use of prepreg fibers can the fibers are directed to be introduced into the layers and the different layers are produced inexpensively.

According to one Another preferred embodiment of the present invention the glass fibers of the fiberglass layers are laid or woven.

The Fiberglass layers can both laid and woven. Again, can advantageously prepreg glass fibers for the Training the glass fiber layers are used. The fiberglass layers are preferred on the outside directed side of the core composite structure, d. h., the Carbon fiber layers lie between the core element and the or the glass fiber layer (s). The glass fiber layers scold zen the inner carbon fiber layers from wear. Additionally serve the glass fiber layers as corrosion protection. Because of the high Conductivity of the Carbon fibers become adjacent to the carbon fibers and easily corroded with these materials in contact. Since glass fibers can serve as an insulator, prevent layers made of glass fibers a corrosion. In addition, glass fibers resistant to scrubbing and therefore offer good protection Wear of the core composite structure. Finally, increase fiberglass layers the outside a core composite structure the impact resistance of the core composite structure.

It is also advantageous that the formation of the carbon fiber layers and the glass fiber layers used resin identical for all layers is. Is for all layers used the same resin, so the contact between the layers are made better.

According to one more preferred embodiment of the present invention has the core composite structure a total thickness of 5-30 mm, preferably from 7-15 mm, more preferably about 10 mm.

The Use of the carbon fibers in the cover layers the core composite structure high strength and bending stiffness at the same time low weight.

The Invention will be described below with reference to exemplary embodiments with reference closer to the enclosed figures explained.

there shows

1 a core composite structure according to a first embodiment; and

2 a core composite structure according to a second embodiment.

1 illustrates the structure of a core composite structure according to a first embodiment of the present invention. The core element here is a honeycomb structure containing meta-aramid fibers 1 used with a specific weight of 1267 g / m ² and a thickness of 8.8 mm of the type Nomex ^® -144.

On this honeycomb structure there is a carbon fiber layer on each side 2 . 3 with a specific gravity of 420 g / m ² using a HTS (High Tenacity Strength) carbon fiber with 12000 (12K) filaments applied per thread. These carbon fiber layers are scrims of the carbon fibers. Preferably, these carbon fiber layers are made from prepreg materials. The tape orientation of the carbon fibers is preferably in the first layer 2 . 3 along the stress, for example in the longitudinal direction of an aircraft, arranged.

On these carbon fiber layers 2 . 3 is according to embodiment in each case a further carbon fiber layer 4 . 5 applied. The fibers of the second carbon fiber layer are oriented perpendicular to the orientation of the fibers in the first carbon fiber layer. The specific gravity of this layer is 308 g / m ² .

On the outside of the core composite structure is a glass fiber layer 6 . 7 applied. Here, an S-glass fiber is preferably used on the higher stress side of the core composite structure. Preferably, on the side of higher stress, another glass fiber layer 8th be applied from S-glass. The specific gravity of the S-glass fiber layer is 192 g / m ^{2 in} each case. On the bottom is a glass fiber layer 7 applied, which has an E-glass fiber. The specific weight of the glass fiber layer 7 the bottom is 86 g / m ² .

The two carbon layers 2 . 4 and the two fiberglass layers 6 . 8th form the upper cover layer 9 and the two carbon fiber layers 3 . 5 and the glass fiber layer 7 the lower cover layer 10 ,

According to the first embodiment of the present invention, all fiber layers 2 . 3 . 4 . 5 . 6 . 7 . 8th That is, both the fiberglass and the carbon fiber layers, an epoxy resin as a matrix material. The total thickness of the core composite structure of the first embodiment is 9.8 mm.

2 shows the structure of a core composite structure according to another embodiment of the present invention. Here, the core element is a honeycomb structure containing meta-aramid fiber 11 with a specific weight of 72 kg / m ² and a thickness of 9 mm.

On each side of this honeycomb structure is a carbon fiber layer 12 . 13 applied with a specific weight of 125 g / m ² . The fibers in this layer are IMS (intermediate modulus strength) fibers with 24,000 (24 K) filaments per filament. The carbon fiber layers according to this embodiment are scrims of the carbon fibers, wherein the fibers are respectively laid parallel to each other. The tape orientation of the carbon fibers is preferably in the first layer 12 . 13 along the stress, for example arranged in the longitudinal direction of an aircraft.

On both sides of the core composite structure are two additional carbon fiber layers directly afterwards 14 and 15 appropriate. The specific gravity of these carbon fiber layers is 123 g / m ² inclusive of the resin. Again, IMS-24K carbon fibers are used again. The scrim of the carbon fibers is preferably at an angle of 45 ° to the scrim of the first layers 12 . 13 ,

On the other side, these layers become two further layers 16 . 17 applied. These third layers are identical to the second layers in construction. Only the direction of the carbon fibers within the fabric differs from the second layers 14 . 15 , The carbon fibers of the layers 16 . 17 are at an angle of 45 ° with respect to the first layers 12 . 13 and at an angle of 90 ° with respect to the second layers 14 . 15 arranged.

Finally, another layer of carbon fibers is applied on each side of the core composite structure on the outside. Again, IMS-24K carbon fibers are used again, with the carbon fiber layer having a specific gravity of 154 g / ^m2 including the resin. The scrim of the carbon fibers is arranged such that the carbon fibers of the fourth layer 18 . 19 an angle with respect to the first layer 12 . 13 of 90 ° and an angle with respect to the third adjacent layer 16 . 17 of 45 °.

Finally, on each outside of the core composite structure, a glass fiber-containing layer 20 . 21 applied. This glass fiber-containing layer comprises an F-glass and serves as corrosion or impact protection.

The Arrangement of the carbon fiber layers within the core composite structure can be made variable. The sequence of orientation of the eggs can change become. For example, it is conceivable that the first layer has a relative orientation of 0 °, the second a relative orientation with respect to the first layer of -45 °, the third Layer a relative orientation with respect to the first layer of 90 ° and the fourth layer is a relative orientation with respect to first layer of 45 °. Any other conceivable construction re the layer sequences and the orientation of the fibers within the Layer is also possible.

The carbon layers 12 . 14 . 16 . 18 and the glass fiber layer 20 make up the upper deck layer 22 and the carbon fiber layers 13 . 15 . 17 . 19 and the glass fiber layer 21 the lower cover layer 23 ,

According to a third embodiment of the present invention, according to the first embodiment, as a core element 1 a honeycomb structure comprising a mixture of para-aramid fibers and meta-aramid fibers.

Commercially, honeycomb structures are available for example as N636 ^® -123. At a thickness of 8.8 mm, such a honeycomb structure according to the second embodiment has a specific gravity of 1082 g / m ² . Such a honeycomb structure thus offers a further weight advantage over the honeycomb structure used according to the first exemplary embodiment. However, this weight advantage does not result in adverse performance data for the honeycomb structure.

According to another embodiment of the present invention, further carbon fiber layers may be applied, for example at an angle of 45 ° and / or 135 ° (corresponding to -45 °) with respect to the fiber direction of the first layer 2 . 3 , However, it is also possible to apply only one carbon fiber layer to the honeycomb structure.

Even though the present invention with reference to preferred embodiments has been described herein, it is not limited thereto, but on diverse Modifiable way.

For example can further carbon fiber and / or glass fiber layers integrated into the structure become. The glass fiber layers can also be formed as a fabric be.

1

Core element made of Nomex ^® honeycomb with a thickness of 8.8 mm

2

layer with HTS-12K carbon fiber in 0 ° direction

3

layer with HTS-12K carbon fiber in 0 ° direction

4

layer with HTS-12K carbon fiber in 90 ° direction

5

layer with HTS-12K carbon fiber in 90 ° direction

6

layer with S-glass fiber

7

layer with E-glass fiber

8th

layer with S-glass fiber

9

Upper topcoat

10

Lower topcoat

11

core element with a honeycomb containing meta-aramid

12

layer with IMS-24K carbon fiber in 0 ° direction

13

layer with IMS-24K carbon fiber in 0 ° direction

14

layer with IMS-24K carbon fiber in 45 ° direction

15

layer with IMS-24K carbon fiber in 45 ° direction

16

layer with IMS-24K carbon fiber in 135 ° direction

17

layer with IMS-24K carbon fiber in 135 ° direction

18

layer with IMS-24K carbon fiber in 90 ° direction

19

layer with IMS-24K carbon fiber in 90 ° direction

20

layer with F-glass fiber

21

layer with F-glass fiber

22

Upper topcoat

23

Lower topcoat

Claims (10)

Core composite structure, in particular in the aerospace sector, with an upper cover layer ( 9 ; 22 ); a lower cover layer ( 10 ; 23 ); and one between the cover layers ( 9 . 10 ; 22 . 23 ) core element ( 1 ; 11 ), which is formed as a honeycomb structure; the cover layers ( 9 . 10 ; 22 . 23 ) facing the core element at least one carbon fiber layer ( 2 . 3 . 4 . 5 ; 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 ) and the core element facing away from at least one glass fiber layer ( 6 . 7 . 8th ; 20 . 21 ) exhibit. Core composite structure according to claim 1, characterized in that the honeycomb structure of the core element ( 1 ; 11 ) has an aramid fiber. Core composite structure according to claim 1 or 2, characterized in that the honeycomb structure of the core element ( 1 ; 11 ) is constructed of an aramid fiber paper. Core composite structure according to at least one of claims 2 or 3, characterized in that the aramid fiber is a para-aramid fiber and / or contains a meta-aramid fiber. Core composite structure according to at least one of the preceding claims, characterized in that the honeycomb structure of the core element ( 1 ; 11 ) has a he xagonal structure. Core composite structure according to at least one of the preceding claims, characterized in that on each side of the honeycomb structure at least two carbon fiber layers ( 2 . 3 . 4 . 5 ; 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 ) are applied. Core composite structure according to claim 6, characterized in that the fibers of the carbon fiber layers ( 2 . 3 . 4 . 5 ; 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 ), preferably in different directions, more preferably at an angle of 80 ° to 100 ° to each other. Core composite structure according to claim 6, characterized in that the fibers of the carbon fiber layers ( 2 . 3 . 4 . 5 ; 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 ), preferably in different directions, more preferably at an angle of 40 ° to 50 ° to each other. Core composite structure according to at least one of the preceding claims, characterized in that the fibers of the glass fiber layer ( 6 . 7 . 8th ; 20 . 21 ) a scrim or a tissue, preferably a scrim, are. Core composite structure according to at least one of the preceding Claims, characterized in that the core composite structure has a total thickness from 5 to 30 mm, preferably from 7 to 15 mm, more preferably of 10 mm.