WO2013107650A1

WO2013107650A1 - Aircraft landing gear part made of fiber composite material

Info

Publication number: WO2013107650A1
Application number: PCT/EP2013/000154
Authority: WO
Inventors: Martin Eckart; Anton Straub; Jörg Meyer
Original assignee: Liebherr-Aerospace Lindenberg Gmbh
Priority date: 2012-01-20
Filing date: 2013-01-18
Publication date: 2013-07-25
Also published as: DE102012001055B4; DE102012001055A1

Abstract

The invention relates to a component consisting of or having at least one fiber composite material. The component is an aircraft landing gear or a part of an aircraft landing gear, in particular of an airplane. According to the invention, the fiber composite material has one or more first fibers which run at an angle of ±10°, preferably at an angle of ±5° and particularly preferably at an angle of 0°, relative to the local central line of the component and/or one or more second fibers which run at an angle of ±30° to ±60°, preferably at an angle of ±40° to ±50° and particularly preferably at an angle of ±45°, relative to the local central line of the component.

Description

CHASSIS COMPONENT OF A FIBERGLASS FUEL AIRCRAFT

The present invention relates to a component consisting of or comprising at least one fiber composite material, wherein the component is a chassis or a part of a chassis of an aircraft, in particular an aircraft.

Fiber composite structural components and methods for their production are known from the prior art.

In known from the prior art components of this type, there is sometimes the disadvantage that the fiber properties are not optimally utilized. Further

Disadvantages consist in a sometimes limited or non-existent damage tolerance as well as inadequate torsion properties as well as inadequate transverse strength and rigidity. The present invention is therefore the object of developing a component of the type mentioned in such a way that this has very good mechanical properties.

This object is achieved by a component having the features of claim 1. Thereafter, it is envisaged that the fiber composite material comprises one or more first fibers which extend relative to the local center line of the component at an angle of ± 10 °, preferably at angles of ± 5 ° and more preferably at an angle of 0 °, that is the component curvature and / or having one or more second fibers which are at an angle of ± 30 ° to ± 60 °, preferably at an angle of ± 40 ° to ± 50 °, and more preferably at an angle of ± 45, relative to the local center line of the component ° run.

The present invention is thus based on the solution concept of achieving particularly good mechanical properties of the component through the use of directed fiber orientation. Thus, it is conceivable to use the good properties in the fiber direction with the setting of a non-quasi-isotropic characteristic. It is conceivable to provide a 0 ° fiber orientation, in particular for tensile and compressive forces and preferably a ± 45 ° orientation of the fibers for torsional loads, wherein the orientation of said first fibers preferably follows the local component curvature.

In a preferred embodiment of the present invention, there is a force flow oriented fiber course. In this case, the first fibers preferably extend at 0 ° angle, that is, they follow the component curvature. These fibers are used in particular for absorbing tensile and compressive loads. Alternatively or additionally, it may be contemplated that fibers in the ± 45 ° angle, e.g. run net-shaped and are wound, for example in a layer around the component. These second fibers provide excellent torsional rigidity of the component.

The first-mentioned fibers follow in a preferred embodiment of the invention, the geometry of the component, that is, ultimately always run tangentially or at 0 ° - Angle relative to the respective local center line of the component. In a preferred embodiment of the invention it is provided that the component comprises a tissue and that the first fibers and / or the second fibers are connected by threads or the like or by an adhesive bond to the tissue. The said fabric, which may also consist of fibers, thus forms in a preferred embodiment of the invention, the substrate for the first and / or second fibers.

The connection between these fibers and the fabric can be made for example by a thread, wire or the like, by the fibers themselves or by an adhesive, for example.

The fibers thus connected to the fabric can then be formed, for example, by folding or winding into a three-dimensional structure, which then ultimately forms said component.

The component may have a matrix which is formed, for example, by a resin or has this.

In a further embodiment of the invention, it is provided that the component has at least one force introduction region, in particular at least one receptacle for a fastening means preferably at least one bolt receptacle and that the first fiber extend completely or partially in the form of one or more loops around this force introduction region. In this case, the so-called loop principle is thus used on the bolt or connections for receiving, for example, tensile forces. Alternatively or additionally, it may be provided that the first fibers are connected to the end face of the force introduction region. Conceivable is thus the connection of an axial force on end faces for the absorption of compressive forces.

As an alternative to the use of the loop principle for the mechanical strengthening of the force introduction region, it is also conceivable to use the state of the art Technology known to achieve force application of tensile and / or compressive forces on bolts in the laminate of the component.

In a further embodiment of the invention, it is provided that the component is designed in several layers, that is forms a laminate of several layers. It is preferably provided that a layer of isotropic or quasi-isotropic material, in particular a fiber composite material follows a position of said first fibers or that the aforementioned layers are arranged alternately. Thus, it is conceivable to combine the known from the prior art construction of a quasi-isotropic layer or fabric with unidirectional fibers, that is, for example, the former fibers. In this way it is possible to combine the favorable impact properties in the outer layers, which are formed by the quasi-isotropic or isotropic material, with the advantageous properties of the unidirectional fibers, that is to say the first fibers, which are particularly advantageous with respect to the transmission of force in the main power flow direction.

By increasing the strength in the main power flow direction, it is possible to reduce the wall thickness of the component.

In a further embodiment of the invention it is provided that the component is at least partially hollow and is preferably designed in cross section with a circumferential wall. Of the invention, however, also includes the case that the wall is not completely circumferential, but for example, is designed as a U-profile or the like.

It is conceivable to design the component such that it provides a variable structure over the circumference of the main cross sections, on the one hand with constant wall thickness but variable fiber orientation (bending effects) on the other hand with variable wall thickness but homogeneous fiber orientation as well as the combination of both possibilities with variable wall thickness and variable fiber orientation , In a further embodiment of the invention, it is provided that the component is designed in multiple layers, for example, consists of a sequence of fabric layers and first fibers and that at least one local thickening is provided in the force introduction region. It is thus possible to reduce the number of individual layers by using so-called sub-preforms with local thickening in the area of force injections or bolt connections.

In a further embodiment of the invention it is provided that in order to increase the ductility and improve the resin properties multiwalled carbonanotubes (MW-CNT) are used. An advantageous proportion is 3% to 5% of the volume of the resin portion. As a resin for the component, which may for example also be part of a component matrix, for example, epoxy resins are used. Alternatively or additionally, the basic materials other than epoxy resin include bismaleimide resin and thermoplastics such as PEEK, PPS, PBT, as well as the fibers e.g. Carbon, aramid, glass, boron etc.

In a further embodiment of the present invention, it is provided that the first and / or the second fibers are present in the form of a continuous, that is to say endless fiber structure or in the form of an interrupted fiber structure. It is therefore conceivable, for example, in the case of continuous fibers, to lay them in a loop shape or else in a wound form, for example the second fibers, which can be wound around the component.

An interrupted fiber structure is conceivable, as they occur, for example, in tissue blanks from roll material.

Furthermore, it can be provided that the surfaces of the component consist completely or partially of isotropic or quasi-isotropic material, in particular of a fiber composite material or have this material. Preferably, the outer layers, that is to say the layers forming the surface of the component, are formed from a quasi-isotropic or isotropic material, in particular fiber material, which with regard to the impact properties of the component Because of the excellent properties of the quasi-isotropic or isotropic material is advantageous. These surface-area fibers are made, for example, of fibers having increased elongation at break, such as glass fibers, as compared to carbon fibers.

In wetterer embodiment of the invention it is provided that the component comprises one or more variably axial tensile cords and / or one or more variable axial pressure strands, which strands are preferably formed loop-shaped and / or wherein these strands preferably consist of the first fibers.

In a preferred embodiment of the invention, the component is a bending strut and / or a tension strut of an aircraft landing gear.

Furthermore, it is advantageous if said fibers and / or said fabric and / or said matrix consist of or comprise carbon fibers and / or the component consists of carbon fiber reinforced plastic (CFRP) or comprises CFRP.

The present invention further relates to a method for producing a component according to one of claims 1 to 14, wherein the method is the Taylor Fiber Placement technique (TFP), the method of Automated Tape Laying (ATL) or is the process of Automated Fiber Placement (AFP). Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing. It is conceivable to carry out a power flow-compatible fiber deposition, which is made possible in particular by an adapted structural calculation and failure analysis. Show it:

1 is a plan view of a bending strut according to the present invention,

2 is a sectional view along section line AA in Fig. 1, 3 is a sectional view along the section line BB in Fig. 1,

4 shows a further schematic plan view of the bending strut according to the present invention,

Fig. 5 is a further schematic plan view of an inventive

Landing gear struts,

6 is an enlarged view of the variable axial fiber orientation of a component according to the present invention;

7 shows a further plan view of a bend strut according to the invention with the sections according to the line A-A and with the detail C.

Fig. 8-11 different embodiments of an upper bend strut for

Connection to the aircraft structure.

Fig. 1 shows by reference numeral 10, a bending strut according to the present invention.

As is apparent from Fig. 1, the bending strut in its plan view in approximately the shape of a Y. In the upper end portions of the two legs 12, 14 are bolt connections or bolts 120, 140th

Furthermore, the buckling strut has a downwardly pointing leg 16, in the lower end region of which there is a further bolt connection 160. This lower bolt connection 160 serves to receive further legs, while the bolt connections 120, 140 serve for the pivotable arrangement of the articulated strut 10 on the aircraft body. By the reference numeral 20, 20 'single fibers, so-called UD fibers are characterized, that is, unidirectional fibers that form the first fibers in the context of the present invention. As can be seen from FIG. 1, these UD fibers 20, 20 'run along the component curvature, that is to say run at a 0 ° angle relative to the local center line and thus tangentially to this local center line.

These fibers extend in the direction of the force flow, wherein the fibers 20 serve in the embodiment shown here to accommodate transverse loads and the fibers 20 'for receiving tensile and compressive forces. In both cases, the fibers, that is to say the first fibers according to the invention run parallel to the center line, that is to say run along the component curvature.

The reference numeral 22 denotes further fibers, which run crosswise according to FIG. 1 and in each case preferably at a 45 ° angle to the local center line of the component 10. These fibers likewise run along the force flow when torsional forces or torsional loads occur. They run at a ± 45 ° angle to the local midline. Advantageous embodiments of this are possible between approximately ± 35 ° and ± 55 ° angles.

Fig. 2 shows a sectional view along the line A-A or B-B in Fig. 1st

As can be seen from this section line, the buckling strut 10 consists of a hollow profile, whose material / material is formed by a quasi-isotropic material 30 (Ql material). This material may also be a fibrous structure, in particular a fibrous web. This may be provided with an epoxy resin and optionally also with Carbonanotubes or multi-walled carbonanotubes in order to increase the ductility and to improve the resin properties, for example of the epoxy resin.

The reference numeral 22 again in Fig. 2, the extending at 45 ° angle fibers or fiber webs, which serve to absorb torsional forces and by the reference numeral 20, 20 ', the unidirectional fibers, in the Main force direction with respect to tensile and compressive forces and shear forces or transverse loads run.

Fig. 3 shows another possible sectional view along the line A-A and B-B in Fig. 1 and illustrates another possible structure of the component 0 in these sectional planes. The reference numeral 30 again denotes the Q1 material and the reference numeral 20, 20 'denotes the unidirectional material (UD), that is to say the unidirectionally extending fibers.

The reference symbol B in FIG. 2 denotes a dominant bending axis of the component.

As can be seen from the sectional views according to FIGS. 2 and 3, the quasi-isotropic material 30 forms the respective surfaces of the component, which is advantageous with regard to the impact properties.

4 again shows a bending strut 10 in a schematic plan view, wherein the reference numeral 20, 20 'again clarifies the fiber course for tensile loads and compressive loads and shows that these fibers 20, 20' follow the component curvature φ. Reference numeral 2 designates the fiber path of the fibers 22 which are suitable for or accommodate thrust loads or torsional loads. The reference numeral 3 finally indicates the loop-like looping of the bolt receiving area 50 through the UD fibers 20, 20 '. About a cross member 170 direct tensile and compressive loads between the bolt connections 120 and 1 0 are recorded.

5 shows a plan view of a bending strut 10. Here, the reference numeral 1 denotes a broken fiber structure which occurs in the case of tissue blanks made of roll material. This figure is illustrative of the prior art without the fibers 20, 20 ^' . Alternatively, these are the fibers 22 without representation of the fibers 20, 20 ^' . Fig. 6 shows an embodiment of a portion of a component 10 according to the invention, wherein by the reference numeral 1, a fiber strand of a standard fabric or scrim and by reference numeral 2 by 90 ° to the fibers 1 offset fiber strand of a standard fabric or jelly is shown.

The reference numeral 3 denotes a variable axial tensile strand and the reference numeral 4 a variable axial pressure cord. These strands 3 and 4 are preferably fixed or positioned on or at 1 and 2.

FIG. 7 shows a further plan view of a bending strut 10 according to the invention. The sectional view AA according to FIG. 7, which is likewise shown in detail in FIG. 7, shows that the bolt region 50 can be formed by a metallic bush 60 which is formed by tension loops is surrounded.

The reference numeral 80 in the upper alternative of the sectional view A-A is a pressure loop or pressure bar.

The lower alternative according to the sectional view A-A differs from the aforementioned embodiment in that instead of the metallic bushing 60, a metallic bushing element 62 is used which has a round side and a straight side. The round side is surrounded by the pull loops 70, while attaching to the straight side pressure loops or pressure bars 80. Both the pull loops 70 and the pressure loops 80 may consist of UD fibers 20, 20 '.

The detail C according to FIG. 7 shows, by the reference numeral 90, a fabric layer. Furthermore, it is shown that between the fabric layers train compression strands or fibers 95 extend, which may be formed as UD fibers. The reference numeral 100 denotes local thickenings, which may be located, for example, in the region of a bolt connection or in a force introduction region. The component according to the invention may consist wholly or partly of a fiber composite material and preferably of CFRP.

The above-described fabrics or the matrix may consist of the same fiber material as, for example, the UD fibers as well as the fibers running at 45 [deg.] And the UD fibers may be made of the same material as the second fibers. This means that, for example, the Q1 material can likewise be a fiber material, in particular a fiber fabric or mesh. To reinforce this fabric, the fabric may be surrounded by or embedded in an epoxy or other resin.

The component according to the invention is preferably produced by the so-called tailored fiber placement technique (TFP), in which the fibers 20, 20 'and / or the fibers 22 are applied to the fabric, for example to the quasi-isotropic fabric 30 by a gluing process or a sewing process be applied. By draping, kinking or folding this fabric, after introduction of a suitable resin, a three-dimensional structure can be obtained, for example the bend strut according to the present invention.

A particularly advantageous embodiment here is the resin injection process, in which the fibers are placed in a cavity and then, after the application of vacuum, the matrix resin is injected under pressure and then cured under pressure.

Alternatively, premixed fiber-matrix materials, so-called pre-pregs, can also be used. In this case, after the fiber-matrix composite deposition, consolidation takes place, for example, by autoclaving or pressing. Also thermoplastic matrix systems can be used. A conceivable field of application for the component according to the invention is a bend strut, preferably upper bend strut, which is preferably used in a nose landing gear of an aircraft.

In today's aircraft on the market, the upper crease strut of nose landing gear is tethered with two bolts to the aircraft structure. A distinction is made here between bolts, which are mounted from "inside", as shown in FIG. 8, and bolts, which come from "outside", as shown in FIG. 9. This is specified depending on the design of the aircraft (connection point in the printed area yes / no). The upper crease struts are correspondingly different.

For an upper bending strut, the variant according to FIG. 9 is significantly more advantageous, since a closed cross section can be used here in the pinhole area and the weight is thereby reduced.

For a lightweight buckling strut, this closed cross-section 200 may be implemented as a pipe or rectangle or other closed profile, as shown in FIG.

So far, only upper crease struts made of CFK are known in which the upper Pintle area is designed open. In these, the pinhole pin, as shown in Figure 8 inserted from the inside. The open-plan area must be reinforced by appropriate material expenditure so that he gets a sufficient rigidity. This rigidity can be achieved by a closed profile with less weight.

The use of a closed profile in the pinhole area is thus advantageous. The pins must then be plugged in from the outside.

The advantage is a lightweight, ie reduced weight upper bending strut in lightweight construction, preferably made of CFRP. It is thus advantageous to form the upper bend strut in lightweight construction (eg CFRP) with a closed profile 200 (eg tube) in the pinhole area, in which the pin-pins are mounted from the outside, as shown in FIG. As a result, a weight reduction of the upper bending strut can be achieved.

Basically, all of the arrangements shown in Figures 8 to 11 can be realized by a bending strut in lightweight construction, preferably CFRP. Particularly advantageous is the use of a component according to the invention as an upper bending strut.

Claims

Component claims

Component consisting of or comprising at least one fiber composite material, wherein the component is a chassis or a part of a chassis of an aircraft, in particular an aircraft, characterized in that the fiber composite material has one or more first fibers relative to the local center line of the component at an angle of ± 10 °, preferably at an angle of ± 5 ° and particularly preferably at an angle of 0 °, ie following the component curvature, and / or having one or more second fibers which are at an angle of ± 30 ° to ± 60 ° relative to the local centerline of the component, preferably at an angle of ± 40 ° to ± 50 ° and more preferably at an angle of ± 45 °.

Component according to claim 1, characterized in that the component comprises a fabric and that the first fibers and / or the second fibers are connected by threads or the like or by an adhesive connection with the tissue.

3. Component according to one of the preceding claims, characterized in that the component has at least one force introduction region, in particular a receptacle for a fastening means and preferably at least one bolt receptacle and that the first fibers extend completely or partially in the form of a loop around the force introduction region and / or that the first fibers are in communication with the face of the force application area.

4. Component according to one of the preceding claims, characterized in that the component is formed of several layers, wherein it is preferably provided that a layer of isotropic or quasi-isotropic material, in particular a fiber composite material follows a position of said first fibers or that the aforementioned layers are arranged alternately.

5. Component according to one of the preceding claims, characterized in that the component is at least partially hollow and is preferably designed in cross section with a circumferential wall.

6. Component according to claim 5, characterized in that the wall thickness of the component over the extent thereof is constant or variable and / or that the fiber orientation of the first and / or the second fibers over the extension of the component is homogeneous or variable.

7. Component according to one of the preceding claims, characterized in that the component is formed in multiple layers and that the component has at least one force introduction region, in particular a receptacle for a fastening means and preferably at least one bolt receptacle, wherein at least one local thickening is provided in the region of the force introduction region ,

8. Component according to one of the preceding claims, characterized in that the component carbon nanotubes, in particular multiwalled carbon Nanotubes and / or at least one resin, in particular at least one epoxy resin.

9. Component according to one of the preceding claims, characterized in that the first and / or the second fibers are in the form of an uninterrupted or in the form of an interrupted fiber structure and / or that the second fibers are present at least partially in wound form.

10. Component according to one of the preceding claims, characterized in that the surfaces of the component completely or partially made of isotropic or quasi-isotropic material, in particular fiber composite material, or comprise this material.

11. Component according to one of the preceding claims, characterized in that the component comprises one or more variably axial tensile cords and / or one or more variable axial pressure strands, which strands are preferably formed loop-shaped and / or these strands preferably of the first fibers consist.

12. Component according to one of the preceding claims, characterized in that it is the component is a bending strut or train-strut of an aircraft landing gear.

13. Component according to one of the preceding claims, characterized in that said fibers and / or said fabric and / or said matrix consist of or comprise carbon fibers and / or the component is made of CFRP or CFK.

14. A method for producing a component according to one of claims 1 to 13, characterized in that the component by the Tailored Fiber Placement technique (TFP), by the method of automated tape laying (ATL) or by the method of the automated fiber placement ( AFP) is produced.