DE102009002404B4 - Biegeträger for forming a bottom plate of a cargo compartment floor of an aircraft, base plate with such a bending beam and aircraft with such a bending beam - Google Patents

Abstract

Bending support (1) for forming a base plate (2) of a cargo compartment floor of an aircraft with a plurality of juxtaposed profiles (3), characterized in that at least between two adjacent profiles (3) means (4) for thermal insulation and mechanical stabilization of Profile (3) is arranged as a foam block (4) made of polyetherimide and the respective profile (3) is designed so weight-reduced that it tends to buckle at an applied load, the respective foam block (4) for thermal insulation and for mechanical stabilization Occurrence of buckling prevented by applied load.

Description

The invention relates to a bending beam for forming a bottom plate of a cargo compartment floor of an aircraft, a bottom plate with such a bending beam and an aircraft with such a bending beam.

The cargo hold floor in aircraft, especially in cargo aircraft, is subject to increased mechanical requirements. The generally substantially flat and continuous cargo hold floor is formed with a plurality of adjoining floor slabs.

The cargo floor construction is exposed to, among other things, high mechanical loads from the cargo itself. The result is usually high local surface pressures by trolleys, the tires of vehicles and dirt particles that can be pressed by tires, rollers or chain links in the surface of the cargo compartment floor. In addition, the so-called "impact" behavior ("impact" behavior) must be given more attention. Handling loads, chains or tools that fall to the ground must not impair the integrity of the cargo hold floor.

Furthermore, due to the high temperature differences of up to 125 ° C occurring during flight operations, no appreciable mechanical stresses can be generated within the hold floor. To achieve this, the floor panels are connected to the cargo compartment floor substructure or so-called "fuselage cell" by means of suitable connecting elements, which permit slight movements in at least one direction parallel to the cargo compartment floor plane (so-called "floating" storage of the cargo compartment floor).

This would provide thermal decoupling of the cargo compartment floor and the fuselage of the aircraft. The outer skin of the aircraft cools during flight to the outside temperature of, for example -55 ° C, the interior, however, is heated. These temperature differences cause a relative expansion of about 1 mm per m in the example of an aluminum structure between the cargo hold floor and the outer skin. For example, for a 17 m cargo compartment floor, this would be 17 mm. For this reason, it is necessary to choose such solutions or materials or constructions, which have only small relative dimensions.

A conventional solution is to use a honeycomb structure with an impact-insensitive surface. Disadvantageously, however, such honeycomb are limited in their local carrying capacity and beyond very sensitive to their Decklagenverklebung in Impact. Conventionally best protection with the highest load-bearing capacity is provided by the metal-string-based plate. A disadvantage of this solution, however, lies in the high heat capacity of the material of the metal stringers. Thus, a relatively large amount of heating energy must be applied to heat a cooled-down aircraft. It is noteworthy that even low relative temperatures to the body temperature of humans lead to increased heat dissipation, thus for example to cold feet of the passengers. The need to heat up such a system leads to an additional change in length of the respective floor panel in the aircraft, which in turn must be compensated design-technically.

In addition, the floor panels also have a supporting function. Because the floor panels have the task to transfer loads, for example, from lashing points in the cargo hold floor via shear forces in the lateral connection to the fuselage skin, whereby their displacement and thus their length is limited. The floor panels, in conjunction with channels in the cargo hold floor, which serve to receive so-called "lashing points", roller conveyors, guide rails or the like, form a statically effective composite and increase its flexural rigidity overall. The bottom plates thus also define the optimum load introduction point for loads which are fastened by means of the lashing points on the cargo hold floor, in the x-direction, ie parallel to the longitudinal axis of the aircraft in the direction of flight.

Due to the required displaceability of the floor panels to compensate for thermal expansion, the floor panels do not act as a continuous beam, but are interpretable only as a carrier on two columns. A weight-optimized solution for this is the "carrier of the same voltage".

Such a carrier or bending beam can be made, for example, in the form of an integrally milled plate. The cutting effort is very high in this case. In addition, such a carrier in milling technology can not be produced with optimum weight.

Alternatively, the floor panels can be formed with sandwich panels whose cover layer is formed with metal. At high local loads and large spans the weight advantage is no longer given. Moreover, the impact strength at which high mechanical point loads occur is problematic. Among other delamination caused by impacts of compact objects are difficult to detect, which weight-increasing security surcharges must be taken into account in the static design.

The US Pat. No. 6,247,747 B1 discloses a panel for a cargo compartment of a truck, the panel comprising two spaced apart FRP plates facing each other, each of the plates comprising a web of reinforcing fibers as a rigid main member, and the panel integrally connecting the FRP plates comprises formed bridge, which is arranged in the space between them.

The DE 103 61 655 A1 discloses a floor heating system for an aircraft, in particular for a cargo aircraft, comprising a floor formed of heatable plates, the panels having continuous first hollow chambers and a supply connected to the first hollow chambers for warm, derived from the cooling electronic devices of the aircraft exhaust air.

The EP 1 864 792 A1 discloses a delamination development preventing structure for a composite panel comprising a foam resin core, two surface plates respectively connected to opposite surfaces of the core with respect to a direction parallel to the thickness of the core, and delamination development preventing members projecting inwardly from the surface plates each sink into the core with respect to directions parallel to the thickness of the core.

Accordingly, it is an object of the invention to provide a bending beam for a floor panel of a cargo hold floor of an aircraft, which does not have the disadvantages described above.

According to the invention, this object is achieved by a bending beam having the features of patent claim 1, by a base plate having the features of claim 11, and by an aircraft having the features of patent claim 12.

Accordingly, a bending beam for forming a floor panel of a cargo compartment floor of an aircraft is proposed which has a plurality of juxtaposed profiles, wherein at least between two adjacent profiles, a device for thermal insulation and for mechanical stabilization of the profiles is arranged.

According to the invention, the device for thermal insulation and for mechanical stabilization of the profiles is designed as a foam block.

According to the invention, the foam block is made of a high-performance thermoplastic. The high performance thermoplastic is especially polyetherimide.

According to the invention, the respective profile is designed so weight-reduced that it tends to buckle at an applied load, the respective device for thermal insulation and for mechanical stabilization prevents the occurrence of buckling with applied load.

Furthermore, a base plate is proposed for forming a substantially continuous cargo compartment floor in a cargo hold of an aircraft, which has a plurality of inventive bending beams explained above, which are arranged next to one another.

Furthermore, an aircraft with at least one bending carrier as described above is proposed.

An advantage of the invention is that the device arranged between two adjacent profiles can fulfill a dual function, namely, on the one hand, the function of the thermal insulation and, on the other hand, the function of the mechanical stabilization of the profiles. In addition, the respective device between the profiles is arranged to save space.

Due to the mechanical stabilization of the profiles according to the invention by the arranged between the profiles devices, the profiles can be interpreted stability-reduced weight, because the profiles must be designed as such not stable.

Such a weight reduction of the plurality of profiles caused as a foam block formed according to the invention a significant weight reduction of the aircraft. In addition to the stabilizing function, the device according to the invention also performs the function of thermal insulation, in particular the function of thermal insulation.

In the subclaims there are advantageous embodiments and improvements of the invention.

According to a preferred development, a respective device for thermal insulation and mechanical stabilization of the profiles between all adjacent profiles of the bending beam is arranged.

An advantage of this development is the optimization of the dual function of the device according to the invention, namely the thermal insulation and the mechanical stabilization.

According to a further preferred development, a respective device for thermal insulation and for the mechanical stabilization of the profiles between the adjacent profiles of a selection of the profiles of the bending beam is arranged.

An advantage of this development is the optimization of the weight reduction, because only between a selection of profiles a device for thermal insulation and mechanical stabilization is provided. The selection of profiles is smaller than the total number of profiles.

An advantage of this development is that the foam block as such is flexible and thus can protect necessary bonds of the bending beam from impact damage.

According to a further preferred development of the foam block is formed as a hollow chamber block. This has the advantage of further weight reduction.

The high-performance thermoplastic is advantageously optimized as a device for thermal insulation and mechanical stabilization of the profiles with regard to the thermal insulation function.

According to a further preferred development, an upper cover layer and a lower cover layer are provided, between which the plurality of juxtaposed profiles and arranged between the profiles foam blocks are arranged.

According to a further preferred development, the upper cover layer is made of a fiber-reinforced aluminum.

According to a further preferred development, the lower cover layer is made of a carbon fiber reinforced plastic, in particular of CFRP.

According to a further preferred development of the respective foam block is glued to the respective two adjacent profiles.

Furthermore, the device is preferably designed to be flexible and thus protects the bond with the cover layer against impact damage.

According to a further preferred embodiment, the upper cover layer, the profiles, the foam blocks and the lower cover layer are glued together, in particular glued over a large area.

According to a further preferred development, the upper cover layer is made of glare or S-glass. Preferably, the upper cover layer has an alternating layer structure of aluminum layers and glass fiber reinforced plastic layers. The glass fiber reinforced plastic layers are in particular GFRP layers.

According to a further preferred embodiment, the respective profile is made of a carbon fiber reinforced plastic and glued to a glass fiber reinforced plastic layer of the upper cover layer of glare. The respective profile is preferably made of CFRP or CFRP.

According to a further preferred development, the respective profile is designed as a C-profile or as an I-profile. Alternatively, the respective profile can also be designed as a T-profile or as a double-T-profile.

The invention will be explained in more detail below with reference to embodiments with reference to the accompanying figures.

From the figures show:

1 a schematic sectional view in the direction of flight of an embodiment of a bending beam according to the invention;

2 a schematic cross-sectional view of the embodiment of the bending beam according to 1 ;

3 a schematic representation of a load case for the embodiment of 1 and 2 ; and

4 a schematic sectional view in the direction of flight of an embodiment of a floor panel according to the invention.

In the figures, the same reference numerals designate the same or functionally identical components, unless indicated otherwise.

In 1 is a schematic sectional view in the direction of flight of an embodiment of a bending beam 1 represented according to the invention.

The bending beam 1 is to form a bottom plate 2 a cargo hold floor of an aircraft and has a plurality of juxtaposed profiles 3 ,

Between at least two adjacent profiles 3 is a facility 4 for thermal insulation and mechanical stabilization of the profiles 3 arranged.

Without restriction of generality shows 1 a bending beam 1 with six profiles 3 and six facilities 4 for thermal insulation and mechanical stabilization of the profiles 3 ,

Preferably, one device each 4 for thermal insulation and mechanical stabilization of the profiles 3 between all neighboring profiles 3 of the bending beam 1 arranged. Alternatively, a respective device 4 only between the neighboring profiles 3 a selection of profiles 3 of the bending beam 1 be arranged (not shown).

The device 4 for thermal insulation and mechanical stabilization of the profiles 3 is formed as a foam block. The foam block 4 is preferably of a high performance thermoplastic.

Furthermore, the bending beam has 1 preferably an upper cover layer 5 and a lower cover layer 6 , Between the upper cover layer 5 and the lower cover layer 6 are the multitude of profiles arranged side by side 3 and those between the profiles 3 arranged foam blocks 4 arranged.

In particular, the upper cover layer 5 made of a fiber-reinforced aluminum. Here is the upper cover layer 5 preferably made of glare (glass-fiber reinforced aluminum) or S-glass. In particular, the upper cover layer has 5 from glare an alternating layer structure of aluminum layers and glass fiber reinforced plastic layers, in particular GFRP layers (GFRP, glass-fiber reinforced polymer).

The lower cover layer 6 is preferably made of a carbon fiber reinforced plastic, in particular CFRP.

Preferably, the respective foam block 4 with the respective two adjacent profiles 3 bonded. In particular, the upper cover layer 5 , the profiles 3 , the foam blocks 4 and the lower cover layer 6 glued together, preferably glued together over a large area.

The respective profile 3 is preferably made of a plastic fiber reinforced plastic, in particular CFK or CFRP (carbon-fiber reinforced plastic). Here is the profile 3 from the carbon fiber-reinforced plastic, preferably with a glass fiber reinforced plastic layer of the upper cover layer 5 glued from glare.

Next is the respective profile 3 designed so weight-reduced that it tends to buckle at an applied load, the respective device 4 for thermal insulation and mechanical stabilization prevents the occurrence of buckling when the load is applied.

Preferably, the respective profile 3 formed as a C-profile or as an I-profile. In relation to 1 shows 2 a schematic cross section of the embodiment of the bending beam 1 to 1 ,

Next shows 3 a schematic representation of a load case for the bending beam 1 after the 1 and 2 ,

Furthermore, in 4 a schematic sectional view in the direction of flight of an embodiment of a bottom plate 2 represented according to the invention. The embodiment of the bottom plate 2 has at least one bending beam 1 to 1 , The dimensions in 4 refer to mm.

Although the invention has been described with reference to preferred embodiments, it is not limited thereto, but modifiable in many ways.

LIST OF REFERENCE NUMBERS

1

bending beam

2

baseplate

3

profile

4

Device for thermal insulation and stabilization of the profiles, in particular foam block

5

upper cover layer

6

lower cover layer

7

rib

Claims (12)

Bending beam ( 1 ) to form a bottom plate ( 2 ) of a cargo compartment floor of an aircraft having a plurality of juxtaposed profiles ( 3 ), characterized in that at least between two adjacent profiles ( 3 ) An institution ( 4 ) for thermal insulation and mechanical stabilization of the profiles ( 3 ) as a foam block ( 4 ) is arranged from polyetherimide and the respective profile ( 3 ) is designed so weight-reduced that it tends to buckle at an applied load, wherein the respective foam block ( 4 ) For thermal insulation and mechanical stabilization prevents the occurrence of buckling when the load is applied. Bending support according to claim 1, characterized in that the respective device ( 4 ) for thermal insulation and mechanical stabilization the profiles ( 3 ) between all neighboring profiles ( 3 ) of the bending beam ( 1 ) is arranged. Bending support according to claim 1, characterized in that the respective device ( 4 ) for thermal insulation and mechanical stabilization of the profiles ( 3 ) between the adjacent profiles ( 3 ) of a selection of profiles ( 3 ) of the bending beam ( 1 ) is arranged. Bending support according to one of claims 1 to 3, characterized in that an upper cover layer ( 5 ) and a lower cover layer ( 6 ) are provided, between which the plurality of juxtaposed profiles ( 3 ) and between the profiles ( 3 ) arranged foam blocks ( 4 ) are arranged. Bending support according to claim 4, characterized in that the upper cover layer ( 5 ) is made of a fiber-reinforced aluminum and / or the lower cover layer ( 6 ) is made of a carbon fiber reinforced plastic, in particular CFK. Bending support according to one of the preceding claims, characterized in that the respective foam block ( 4 ) with the respective two adjacent profiles ( 3 ) is glued. Bending support according to one of claims 4 to 6, characterized in that the upper cover layer ( 5 ), the profiles ( 3 ), the foam blocks ( 4 ) and the lower cover layer ( 6 ) are glued together. Bending support according to one of claims 5 to 7, characterized in that the upper cover layer ( 5 ) is made of glare or S-glass, which has an alternating layer structure of aluminum layers and glass fiber reinforced plastic layers, in particular GFRP layers. Bending support according to one of claims 4 to 8, characterized in that the respective profile ( 3 ) made of a carbon fiber reinforced plastic, in particular of CFRP or CFRP, and with a glass fiber reinforced plastic layer of the upper cover layer ( 5 ) is glued from glare. Bending support according to one of claims 1 to 9, characterized in that the respective profile ( 3 ) is formed as a C-profile or as an I-profile. Bottom plate ( 2 ) to form a substantially continuous cargo compartment floor in a cargo hold of an aircraft, which has a plurality of juxtaposed bending beams ( 1 ) according to one of claims 1 to 10. Aircraft with one or more bending beams according to one of claims 1 to 10.

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