DE19726799C2 - Connection arrangement for fiber composite sandwich structures in modular construction and method for producing the connection arrangement - Google Patents

Description

The invention relates to a connection arrangement for fiber composite sandwich Structures in modular construction from parts to be joined, which are attached to their ends Lip joints are provided, and in which connecting elements are provided, which are fitted between the joining lips of joined parts in order to to form a non-positive connection of the parts to be joined. The invention relates also a method for producing such a connection arrangement.

Nowadays large fiber composites are used structures in the field of aircraft, ship and rail vehicle construction becoming more and more important. Due to the high load capacity in Verbin With a low structural weight, sandwiches are often offered structures, but their large-scale production often involves manufacturing technology African problems fail. The ideal solution is therefore a modular one Structure of the overall structure from individual prefabricated semi-finished products hen. The individual prefabricated semi-finished products must then be protected by suitable ver binding technology combined to form the large-area fiber composite structures become.

It is known to use individual joining parts as prefabricated semi-finished products To provide shaft. With such a shaft, both joining parts are at an angle of about 1:20, so L = 20 H, where L is the length and H the The height of the shaft is touched. By means of this shaft to the individual Joined parts are then set up a non-positive joining connection. This Technology has proven itself for repair measures. The in relation to Component thickness 20 times longer joining area includes a large fer technical effort, in addition to high demands on the contour accuracy is also associated with considerable space requirements. This technology is less for the series and large because of the costly effort suitable for series production.  

By Gerd Hintersdorf, "glued honeycomb constructions", in: Ferti gungstechnik und Betrieb, 12th year 1962, number 8, page 533-537, is in another connection has already been proposed, two so-called Wa assemble benplatten in that the adjacent one end face Honeycomb areas are removed and a honeycomb flap in the resulting free space is glued in.

A similar construction is in DE-GM 18 76 723 for the together keep proposed by sandwich panels. It is also about two completely to connect flat sandwich panels to each other at the front and it will proposed between protruding ends of the outer layers of the Sandwich panels with a core insert corresponding to their thickness and area insert the sandwich plate adapter.

DE 25 05 232 A1 also suggests shell construction panels of this type and Way to connect each other at the front. Finally, DE 94 18 409 U1 would like to create a tent floor plate in which wipe two cover layers Core is inserted, at least one of the cover layers as a metal plate be trained. This is particularly important here to keep the panels completely level to keep. A coupling between the core elements is provided, wherein the coupling profiles are connected to the cover layers.

These well-known concepts are neither intended nor suitable To create fiber composite sandwich structures in modular design that too high demands have grown, such as in the area of Aircraft, ship and rail vehicle construction can occur. All these Known proposals essentially come from the construction sector and are not be able to cope with changing loads caused by movement can arise.  

The invention is therefore based on the object of a non-positive connection arrangement for fiber composite sandwich structures in modular construction create a high degree of automation at low cost siert, where also high demands are met. About that In addition, a method for producing such Connection arrangement are proposed.

The object is achieved in a device by both in claim 1 and solved by the invention defined in claim 5. In one case it will solved by the invention defined in claim 7. Further training of the Invention are defined in the subclaims. This will make one Connection arrangement for fiber composite sandwich structures in modular construction created the defined and reproducible connections by friction realized. The outer surface of the sandwich structures assembled individual fiber composite modules or joining parts is uniformly smooth and avoids thereby adverse influences on the profile of an adjacent flow. The Joining surfaces of the individual joining parts advantageously enable self-zening tration and therefore a high degree of automation with simple Handling tools. A series and large series production can take place with a connection arrangement according to the invention.

The firmly inserted between the joint lips in the area of the joining surfaces connecting elements, in particular glued therein, are manufactured separately and surrounded on all sides by a skin opposite the joining surfaces.

This skin ensures an absolutely complete connection and thus power transfer the connecting elements with all joining surfaces of the two adjoining Fiber composite sandwich structures. All suggestions from the state of the art only connect certain sub-areas of the connection used there elements with the cover layers. However, skin becomes all-round Gluing or similar fastening possible.  

In principle, a connection arrangement for fiber composite sandwich structure tures in modular design, with joining parts of the structures being provided, ge create, in which the parts to be joined are provided with joint lips on their end faces, and in which connecting elements are provided which are shaped so that they fit between the joining lips of joined parts or are fitted and a non-positive connection of the joining parts is formed. An upper and a lower joint lip are preferably provided. The upper Joint lip is preferably in the plane of the outer surface of the parts to be joined arranged, whereas the lower joint lip at an angle to the bottom or the inner surface of the joining parts is arranged so that self-centering the joining surfaces of the joined parts is achieved.

The skin surrounding the connecting elements can in particular in two variants can be provided.

A first variant of the connecting elements is constructed so that a thin fiber-reinforced outer skin and a foam core by the fiber reinforced outer skin is provided. The outer skin has plans preferably a fiber orientation that meets the requirements. Should she against Protected against torsion, it preferably has a ± 45 ° fabric Carbon fibers. However, the individual fibers are at a 90 ° angle  Arranged as unidirectional layers to each other, tensile or compressive forces be intercepted.

The foam core preferably has a low density. This makes it very light, according to the requirements. The outer skin of the connecting elements can either be particularly preferably made by braiding technology; it is particularly advantageous for the connecting element as a semifinished product to be produced in large quantities. The Verbindungsele element can also preferably have sewn fiber fabrics or knitted fabrics with moderate elasticity. Such a moderate elasticity lies at values higher than the current assessment basis of ε _crit = 0.4% for fiber composite structures used for example in aviation. The damage tolerance of the structure is significantly improved by three-dimensional reinforcement as a result of sewing the fiber scrim or fiber fabric, since cracks that occur are severely hampered in their spread. As a result, the extensibility can be increased, for example, to values of ε _crit = 0.7 to 0.8%.

In an alternative variant, a corresponding connecting element is of this type manufactured that a flexible fabric hose pre-soaked with liquid resin is provided with an inner liner. Such a fabric hose with an inner liner is in the joint surface between the joint lips of two abutting Joined parts inserted. Overpressure is generated inside the inner liner. Before the excess pressure is preferably raised by inflating the inner liner with a hot water sen or warm medium, especially with warm air or superheated steam. The fabric hose surrounding the inner liner lies against the con the joining surfaces of the abutting joining parts. Especially before is added by means of the heating medium to inflate the inner liner at the same time the temperature required to harden the resin of the fabric hose condition defined. This connects the resin to the fabric hoses the parts to be joined in the area of the joining surfaces between the joining lips of the abutting joining parts advantageously with one another, glues them into the special with each other.

In order to explain the invention in more detail, the following are examples play a connection arrangement for fiber composite sandwich structures in Modular construction described using the drawings. These show in:

Fig. 1 is a perspective view of a flat joining part with OF INVENTION to the invention joining lips,

Fig. 2 is a perspective sectional view of the joined parts to be joined according to Fig. 1 according to the invention connecting elements,

Fig. 3 is a perspective view of a first embodiment of a connecting element according to the invention,

Fig. 4 shows a second embodiment of a connec tion element according to the invention, and

Fig. 5 is a perspective sectional view of a curved sandwich structure in modular design with joint lips and connecting elements according to the invention.

Fig. 1 shows a perspective view of a substantially flat joining member 10 with joining lips 11, 12. The joining part 10 is built up as a sandwich structure. At its outer edge protrude on all sides on the top 13 and the underside 14 of the joining part 10, the joining lips 11 , 12 protrude. The upper joining lip 11 is arranged in the plane of the top 13 or outer surface of the joining part 10 . The lower joining lip 12 is arranged at an angle to the underside 14 or the inner surface of the joining part 10 . The underside of the upper joining lip 11 , an outer wall 15 of the joining part 10 and the top of the lower joining lip 12 together form a joining surface 16 .

FIG. 2 shows a perspective sectional view through the joining part 10 shown in FIG. 1 with joining parts 20 , 30 attached on both sides. The joining parts 20 , 30 also each have an upper joining lip 21 , 31 and a lower joining lip 22 , 32 . The respective upper joint lips 11 , 21 , 31 abut each other plan. Characterized in that the upper joining lips lie in one plane, there is a flat outer surface of the entire structure on the upper sides 13 , 23 , 33 of the joining parts. The outer contour of the individual modules joined together in the form of the joining parts in sandwich construction is not affected by this.

The two joining parts 20 , 30 also have lower joining lips 22 , 32 arranged at an angle to the respective underside 24 , 34 of the joining parts. In the by the adjacent joining parts 10 , 20 and 10 , 30 with Außenwan openings 25 , 35 resulting joining surfaces 16 , 26 and 16 , 36 , positive and non-positive connection elements 40 are inserted.

The connecting elements 40 are shaped and fastened within the joining surfaces in such a way that they enable a non-positive connection of the joining parts 10 , 20 or 10 , 30 which are joined together. By providing the lower joining lips arranged at an angle to the underside of the respective joining parts, self-centering of the connecting elements 40 in the respective joining surfaces 16 , 26 and 16 , 36 is created.

The connecting elements 40 are preferably glued within the joining surfaces 16 , 26 and 16 , 36 , respectively.

The structure of the separately manufactured fasteners is as follows Figures described using two examples.

In Fig. 3, a first embodiment of a connec tion element 40 according to the invention is shown in a perspective view. The connecting element 40 has a thin fiber-reinforced outer skin 41 . The outer skin 41 completely encloses an inner foam core 42 . The foam core 42 preferably has a low density. The outer skin 41 is preferably provided with a fiber orientation of its fabric that is suitable for the stress. For example, a ± 45 ° orientation of a carbon fiber fabric can be provided. The fiber-reinforced outer skin 41 can, for example, be produced by fiber braid technology. This makes it possible to produce in large numbers. Alternatively, however, production can also be carried out by means of sewn fiber fabrics or knitted fabrics with moderate stretchability. In any case, the fiber-reinforced outer skin 41 should adapt to the shape of the foam core 42 .

The foam core 42 is shaped in such a way that it fits optimally into the joint surfaces between the individual joined parts. The foam core is rod-shaped and essentially hen with a pentagonal cross-section. Three sides of the pentagon are arranged at 90 ° to each other. The two remaining sides are joined at an obtuse angle and are half the length of the opposite side. Due to the obtuse-angled joining of the two lower sides, these form the angle of the two lower joining lips to one another and to the perpendicularly arranged outer wall 15 , 25 and 15 , 35 of the respective joining parts 10 , 20 and 10 , 30 according to FIG. 2.

In Fig. 4, a second embodiment of a connec tion element 50 is shown. At the same time in Fig. 4, the connecting element 50 is shown in the insertion within the joining parts 10 , 20 and 10 , 30 of FIG. 2.

The connecting element 50 has an outer fabric hose 51 . An inner liner 52 is provided on the inside of the fabric hose 51 . The fabric hose 51 is manufactured as a flexible component that is pre-saturated with liquid resin. The fabric hose with inner liner initially has a round cross section when it is not inserted into the joining surfaces.

For the frictional joining of the joining parts 10 , 20 or 10 , 30 , the fabric hose with inner liner is inserted into the joining surfaces 16 , 26 or 16 , 36 a. An overpressure is then generated in the inner liner. The overpressure is preferably generated with a warm or hot medium. For example, warm air or hot steam is blown into the inner liner, which inflates it. The fabric liner surrounding the inner liner 51 thereby lies against the contour of the joining surfaces 16 , 26 or 16 , 36 of the abutting joining parts 10 , 20 or 10 , 30 . By blowing in a warm or hot medium, the temperature required for curing the resin of the fabric tube 51 is generated. A corresponding temperature condition can be set in a defined manner by appropriately selecting the heating medium for blowing in and inflating. The resin of the fabric hose is thereby heated and connects, or glued the joint parts 10 , 20 and 10 , 30 in the area of their joining surfaces 16 , 26 and 16 , 36 mitein other. As a result, the resin contributes to the stability of the connecting element 50 .

After the inflation and curing of the resin, the connecting element 50 has the shape corresponding to the cavity between the joining surfaces 16 , 26 and 16 , 36 , respectively. This shape also corresponds to the external shape of the connecting element 40 according to the previous figure.

In Fig. 5, an alternative embodiment of the central joining part is shown as a curved joining portion 60. The curved joining part 60 also has an upper joining lip 61 and a lower joining lip 62 . The abutting upper joint ribs 61 and 21 or 61 and 31 form a flat outer surface of the overall structure. The respective lower joint lip 62 protrudes from the underside 64 of the curved joining part 60 at an angle. In the existing joining surfaces 66 , 26 and 66 , 36 connecting elements 70 are inserted. These correspond essentially to the connecting elements according to FIG. 3 and FIG. 4. Because of the outer walls 65 of the curved joining part 60 provided with a slight inclination to the vertical, the connecting elements 70 are also provided with a corresponding inclination of their walls abutting these outer walls 65 . The other structure of the connecting elements corresponds to the connecting elements according to FIG. 3 or 4. Alternatively, of course, instead of the structure according to FIG. 3, a structure of the connecting elements according to FIG. 4, namely by providing a fabric hose with an inner liner, can be provided. Precisely because of the inclined outer walls 65 and the resulting different joint surface angle, a construction of the connecting elements according to FIG. 4 proves to be particularly advantageous.

By providing the corresponding joining lips on the joining parts in the form of The individual joining module can be fitted in the upper and lower joining lips Glue the sandwich structure together to complete structures. In the area of Lightweight structures made of fiber composite materials are the connector according to the invention elements in connection with the upper and lower joint lips on the individual joining parts very useful tools for the assembly of the light sandwich structures.

Such overall structures made up of modules in sandwich construction fiber composite materials are particularly advantageous in the flight area, used in rail vehicle construction and shipbuilding.  

Reference list

10th

Parts to be joined

11

Joint lip / upper joint lip

12th

Joint lip / lower joint lip

13

Top

14

bottom

15

Outer wall

16

Joining surface

20th

Joining part

21

upper joint lip

22

lower joint lip

23

Top

24th

bottom

25th

Outer wall

26

Joining surface

30th

Joining part

31

upper joint lip

32

lower joint lip

33

Top

34

bottom

35

Outer wall

36

Joining surface

40

Fastener

41

Outer skin

42

Foam core

50

Fastener

51

Fabric hose

52

Inner liner

60

curved joint

61

upper joint lip

62

lower joint lip

63

Top

64

bottom

65

Outer wall

66

Joining surface

70

Fastener

Claims (11)

1. Connection arrangement for fiber composite sandwich structures in modular construction, from joining parts ( 10 , 20 , 30 , 60 ), which are provided on their end faces with joining lips ( 11 , 12 , 21 , 22 , 31 , 32 , 61 , 62 ), and at the connecting elements ( 40 , 50 , 70 ) are provided, which are fitted between the joining lips of joined parts ( 10 , 20 , 30 , 60 ) to form a non-positive connection of the joined parts, characterized in that
that the connecting elements ( 40 , 50 , 70 ) are manufactured separately and are firmly glued into the joining surfaces for producing the non-positive connection, and
that the connecting elements ( 40 , 50 , 70 ) have a thin fiber-reinforced outer skin ( 41 ) and a foam core ( 42 ). 2. Connection arrangement according to claim 1, characterized in that the outer skin ( 41 ) has a stress-oriented fiber orientation and the foam core ( 42 ) has a low density. 3. Connection arrangement according to claim 1 or 2, characterized in that the outer skin ( 41 ) of the connecting elements ( 40 ) is made by braiding technology. 4. Connection arrangement according to claim 1 or 2, characterized in that the outer skin ( 41 ) of the connecting elements ( 40 ) consists of sewn fiber fabrics or knitted fabrics with moderate elasticity, in particular with an elasticity of ε = 0.7 to 0.8% . 5. Connection arrangement for fiber composite sandwich structures in modular construction, from joining parts ( 10 , 20 , 30 , 60 ), which are provided on their end faces with joining lips ( 11 , 12 , 21 , 22 , 31 , 32 , 61 , 62 ), and the connecting elements ( 40 , 50 , 70 ) are provided, which are fitted between the joining lips of joined parts ( 10 , 20 , 30 , 60 ) to form a non-positive connection of the joined parts, characterized in that
that the connecting elements ( 40 , 50 , 70 ) are manufactured separately and are firmly glued into the joining surfaces for producing the non-positive connection, and
that the connecting elements were formed from a flexible fabric hose ( 51 ) pre-impregnated with liquid resin with inner liner ( 52 ) and hardening of the resin. 6. Connection arrangement according to one of the preceding claims, characterized in
that an upper joint lip ( 11 , 21 , 31 , 61 ) lies in the plane of the outer surface of the joining parts, and
that a lower joint lip ( 12 , 22 , 32 , 62 ) is arranged at an angle to the inner surface or underside ( 14 , 24 , 34 , 64 ) of the joining parts such that self-centering of the joining surfaces ( 16 , 26 , 36 , 66 ) from mutually joined parts is achieved. 7. The method for producing the connection arrangement according to claim 5 or according to claim 5 and 6, characterized in that for the production of the connecting elements ( 50 ) flexible fabric hoses ( 51 ) with inner liner ( 52 ) are soaked with liquid resin. 8. The method according to claim 7, characterized in that the fabric hoses ( 51 ) with inner liner ( 52 ) are inserted into the joining surfaces ( 16 , 26 , 36 , 66 ) between the joining lips, and an overpressure is generated in the inner liner ( 52 ) . 9. The method according to claim 7 or 8, characterized in that the fabric hose ( 51 ) to the contour of the joining surfaces ( 16 , 26 , 36 , 66 ) by inflating the inner liner with a warm or hot medium, in particular with warm air or hot steam , creates. 10. The method according to any one of claims 7 to 9, characterized in that by means of the warm or hot medium for inflating the inner liner ( 52 ) temperature conditions for curing the resin of the fabric tubes ( 51 ) are set in a defined manner. 11. The method according to any one of claims 7 to 10, characterized in that the resin of the fabric hoses ( 51 ) connects the joining parts ( 10 , 20 , 30 , 60 ) in the region of their joining surfaces between the joining lips, or glues them together.