DE102008006981B3 - Producing a sandwich structure in air- and space flight area, comprises applying a heating material on a side of a sandwich structure material, and bringing a reinforcing element into the core structure material and the heating material - Google Patents

Abstract

The method for the production of a sandwich structure (1) in air- and space flight area, comprises applying a heating material (8, 9) on a side of a sandwich structure material (2, 3), bringing a reinforcing element (16, 17, 18) in the structure material and the heating material in such a way that the element extends itself through the sandwich structure material and the heating material and has a section overcoming over the heating material, heating-up the heating material for softening the section and forming the section with the softened area as pivot for forming the structure. The method for the production of a sandwich structure (1) in air- and space flight area, comprises applying a heating material (8, 9) on a side of a sandwich structure material (2, 3), bringing a reinforcing element (16, 17, 18) in the sandwich structure material and the heating material in such a way that the reinforcing element extends itself through the sandwich structure material and the heating material and has a section overcoming over the heating material, heating-up the heating material for areawisely softening the overcoming section and forming the overcoming section with the softened area as pivot for forming the structure. The overcoming section is molded in such a way that it comes to the heating material or to an intermediate material applied between the heating materials for the fabrication. A covering material is applied on the heating material or the intermediate material together with the overcoming section overlying on the intermediate material or the heating material. The heating material, the intermediate material, the further intermediate material, the reinforcing element and/or the covering layer have a matrix (36), which is hardened by heating the heating material. The matrix flows in a ring area between the reinforcing element and the sandwich structure material and tightly locks the element and the sandwich structure material. A further intermediate material is subjected on the other side of the sandwich structure material in the area of the ring area. The matrix of the intermediate material is flow freely by heating the heating material. The overcoming section of the reinforcing element has a partially cross-linked duroplastic material, thermoplastic material and/or fibers. The heating material is formed as ohmic heating material with electric contacts for a connection to a current source. The heating material is formed out of carbon material and glass.

Description

The The present invention relates to a method for producing a Structure, in particular a core network in the aerospace sector, as well as such a structure, in particular a core composite in the air and space area.

In High-tech areas, such as aircraft construction, find core networks because of their good relationship from stiffness and strength to density a wide range of applications. A core network usually consists of a core layer, which and on each side has a cover layer.

Around to strengthen such a core network, it has become known rod-shaped Reinforcing elements, For example, so-called "pins", in the core layer, for example, a rigid foam, to stab in the thickness direction, before the cover layers are applied on the top and bottom sides. Such pins can be prepared for example in the pultrusion process. In the pultrusion process be initial dry fibers impregnated with a thermosetting matrix and then by a nozzle pulled, this is heated. This leads to at least partial crosslinking the matrix, eliminating the reinforcing elements a certain rigidity for have a piercing thereof in the core layer.

Around now another reinforcement of the core network is the next step in the state the technique has been developed. The reinforcing elements are equipped with a of such length, they have a projecting portion both above and below the core layer exhibit. This supernatant Sections of reinforcing elements be in a further step by means of a heated pliers individually folded over so that they engage behind the core layer. In one further step then on the top and bottom of the core layer together each on these resting, protruding portions of the reinforcing elements applied the two above-mentioned cover layers. The two usually of a fiber-prepreg impregnated with a resin matrix Cover layers are then together with the partially crosslinked reinforcing elements and the core layer cured under pressure and heat.

at the approach described above has proved to be disadvantageous, that first each of the outstanding ones Sections of reinforcing elements individually gripped with the heated pliers and then one must be waited for predetermined period of time until the supernatant Section is sufficiently softened, then this behind to fold over the core layer. This process is comparative time and thus expensive.

The DE 10 2005 035 681 A1 describes a manufacturing process for reinforcing core materials for core composites as well as core composite structures. The DE 10 2005 024 408 A1 describes a method for reinforcing foam materials. The US 6,291,049 B1 describes a sandwich structure and a method for producing such using pins.

It is therefore an object of the present invention, an improved method for producing a structure, in particular a core composite in the air and space area, and / or a structure, in particular a Aerospace Core Alliance to provide what or which in particular a reduction of the waiting time for heating the protruding Sections to soften the same allows.

According to the invention this Task by a method having the features of the claim 1 solved.

Accordingly, a Method for producing a structure, in particular a core composite in the Aerospace area, provided with the following steps. First becomes a heating material on one side of a core structural material applied. In a further step, a reinforcing element introduced into the core structure material and the heating material in such a way that is the reinforcing element through the core structure material and the heating material and one over the heating material protruding Section has. After that, the heating material for at least partially softening the protruding Heated section. Subsequently becomes the supernumerary Section with the softened area as a fulcrum to make the Structure reshaped.

The The idea underlying the present invention is that that the heating - compared to the initially described approach according to the prior art - parallelized can be because the heating material is substantially adjacent (ie contacting or with slight gap) at each of the pivots of the protruding sections is arranged and thus upon activation of the heating material Heat is supplied to each of these fulcrums substantially simultaneously. in the Ways of this parallelization thus results in a time and cost savings across from the well-known, sequential approach.

In the dependent claims are advantageous Adhesive embodiments and improvements of the invention.

Under the term "reinforcing element" is intended here preferably a rod-shaped Semi-finished goods are understood. This semi-finished product can be used in pultrusion or extrusion process can be produced. The semi-finished product can for example, a round, triangular, quadrangular, hexagonal, tubular or other cross-section. The reinforcing element can with or without reinforcing fibers, for example carbon fibers be. The reinforcing element can also additionally to the reinforcing fibers - a thermoplastic or thermosets.

Under The term "core structure material" is presently preferred a foam material, in particular a rigid foam, a prepreg material or a dry scrim or tissue, a metallic foil, as well any combination of the same, to understand. Especially preferred is the core structure material self-supporting, that is, that It has its own stability without tools.

If in the present case of the "application" of a material is spoken to another material, so is in particular a Laying (and / or applying) and cohesive bonding between the one and the other material meant.

Prefers Become a variety of reinforcing elements introduced into the core structure material and the heating material.

Prefers becomes the supernumerary Section formed by means of a roller, which substantially is moved parallel to the core structure turmaterial. To be favoured by means of the roller several protruding Sections of the plurality of reinforcing elements transformed at the same time.

For example For example, the structure may be made as a hollow structure, i. H. there are provided two core structure materials, which provide a distance between have. The distance between the two core structure materials is bridged by the reinforcing element, which connecting them together. The heating material can then each facing away from the other core structural material Side be applied. The reinforcing element extends through both core structure materials as well as through both heating materials and optionally by an applied to each of the heating materials Intermediate material. The cover layers are in turn on each of the Heating materials or each of the intermediate materials together the one resting on these, standing over Applied portion of the reinforcing element.

Of course you can in the above-described arrangement, the core structural material as well be formed as a solid structure. That is, the one described above Cavity between the two core structural materials is also filled by core structure material; So it's just one - though in certain circumstances thicker - core structure material intended.

This reinforcing elements can For example, with different angles through the core structure material extend. Preferably, they extend in the event that the core structural material is formed as a core structure layer, in the thickness direction or at an angle not equal to 90 °, for example 30 to 70 °, to the thickness direction through this. The struts thus formed reinforce that Core structural material.

According to one preferred embodiment of the method according to the invention is the supernatant Section reshaped so that it on the heating material or on a lying on this intermediate material comes to rest. There is a possibility after or before the heating material on the core structure material is applied to apply an intermediate material on the heating material. The supernumerary Section may be in a reshaping step for Harden the entire structure with the heating material or the intermediate material firmly connected. For this points the heating material or the intermediate material, preferably a matrix, in particular, an epoxy resin, into which the reshaped, projecting portion at least partially immersed and then cured with this. Advantageously, the intermediate material of a very strong fiber composite material formed, for example, a CFRP prepreg with a very high Fiber density. The intermediate material can then have a very firm anchoring point for the supernumerary Section of the reinforcing element form.

The Heating material is preferably applied directly to the core structure material applied. The intermediate material is preferably also directly applied to the heating material.

According to one further preferred embodiment of the method according to the invention becomes a covering material on the heating material or the intermediate material together with the resting on this section of the reinforcing element applied. This will be the supernumerary Section of the reinforcing element advantageous between the heating material or intermediate material and the deck material "sanded", resulting in one more higher Strength of the structure produced leads.

According to one further preferred embodiment of the method according to the invention has the heating material, the intermediate material and / or the cover layer a matrix, which by means of the heating of the heating material becomes fluid, causing the matrix in an annulus between the reinforcing element and the core structural material flows and thus closes tightly. The reinforcing element is preferred by piercing the core structural material and introduced the heating material. This forms - at the microscopic level - an annulus between reinforcing element and core structure material or heating material. In the way of Above described development of the annulus can thus easily be sealed, thereby preventing ingress of harmful Substances in the structure can be prevented.

If in the present case is spoken by a "matrix", so preferably a thermoset matrix is meant. alternative however, it may also be a thermoplastic or other type of matrix be meant.

Prefers Advantageously, the heating material has, in addition to the components, which the release of heat allow - for example one or more electrical resistance elements -, the matrix for the Annulus on. As a result, the matrix no longer needs to be separated be provided, resulting in a process simplification can. Alternatively, the intermediate material or the cover layer the matrix for have the annulus.

According to one further preferred embodiment of the method according to the invention becomes at least on the other side of the core structural material in the region of an annular space between the reinforcing element and the core structure material applied a further intermediate material, wherein a matrix of Intermediate material becomes fluid by heating the heating material, whereby the matrix flows into the annulus and thus closes it tight. The other side of the core structure material is preferably one side opposite, where the annulus from one to the other side of the core structure material extends. The annulus can also by piercing the reinforcing elements be formed. The matrix of the intermediate material closes the annulus substantially on the other side of the core structure material. This may be additional or alternatively to the closure of the annulus described above on one side of the core structure material. Also by this will be an intrusion of harmful Prevents substances from the environment in the structure. Will that be further intermediate material, for example in the form of a coating only in the area of the annulus on the other side of the core structure material adjacent to the reinforcing element applied, for example, sprayed, the desired tightness be achieved material saving.

According to one further preferred embodiment of the method according to the invention shows the heating material, the intermediate material, the additional intermediate material, the reinforcing element and / or the cover layer on a matrix, which by means of the heating of the Heating material is cured. Advantageously, the entire structure can thus be cured, d. H. it is no longer necessary to put the structure in an oven or Insert autoclave to harden them there under pressure and heat. The Matrix is for it as a thermosetting matrix, in particular epoxy resin matrix formed.

According to one further preferred embodiment of the method according to the invention has the reinforcing element a only partially crosslinked thermoset material and / or fibers. It is crucial that the supernumerary Section of the reinforcing element by heating the heating material (still sufficient) softened is.

Under "partially crosslinked" is present Degree of crosslinking between 0 and 100% meant. Preferably, the supernatant Section of the reinforcing element but a degree of crosslinking of, for example, 30 to 80%, which a dimensional stability of the reinforcing element guaranteed, so that this is inserted into the core structure material can be.

Under "curing" is present in the increase of the degree of crosslinking in the matrix, in particular including, in this case, achieving a degree of crosslinking of nearly 100% to understand.

According to one further preferred embodiment of the method according to the invention is the heating material as ohmic heating material with electric Contacts for a connection formed on a power source. The ohmic heating material has such a resistance that when flowing through the same This provides a suitable heating power with electricity. alternative It is also conceivable to provide the heating material inductively heated. It could the heating material such as carbon fibers, carbon nanoparticles or Have metal particles. These can then by means of an induction device to release the desired Heating power "wireless" to be stimulated.

According to a further preferred development of the method according to the invention, the heating material is made of one with electrical contacts provided carbon material and / or glass formed. Such heating material is readily available.

The Heating material, core composite material, intermediate material, other intermediate material and / or Cover material is preferably formed as a layer.

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

The figure shows in a sectional view a process state in the manufacture of a structure 1 according to a preferred embodiment of the invention.

First, two core structure layers 2 and 3 with a distance 4 held each other, where they have a cavity 5 form between them (referred to herein as a hollow structure). The core structure layers 2 and 3 are preferably formed from a foam, in particular a rigid foam.

As an alternative to the hollow structure, it is also possible to use a single core structure layer (in the present case referred to as a solid structure), in which case the reference symbol in FIG 5 designated cavity would be filled with core structural material. All versions below apply accordingly to the full structure.

The core structure layers 2 . 3 are each on their side facing away from each other 6 respectively 7 with heating layers 8th respectively 9 Mistake. The heating layers 8th and 9 are preferably formed from an ohmic heating material. This may be, for example, carbon fiber material 9a act with glass and a matrix 9b , in particular an epoxy resin, is added. The heating layers 8th . 9 have electrical connections 10 and 11 respectively 12 and 13 on. Here are the connections 11 and 12 by means of an electrical conductor 14 directly coupled with each other. To the connections 10 and 13 becomes a power source 15 coupled, which is adapted to receive a current from the contact 10 through the heating layer 8th (ie through the fibers 9a ) through the contact 11 , through the pipe 14 , through contact 12 , through the heating layer 9 and through contact 13 turn back to the power source 15 to send.

Before or afterwards, for example, reinforcing elements produced in the pultrusion process 16 . 17 and 18 (the reinforcing element 18 is only shown in dashed lines, since it is located behind the section shown in the figure) at an angle of for example 45 ° through the heating layer 8th , through the core structure layer 2 , through the core structure layer 3 the cavity 5 bridging and through the heating layer 9 stung. This forms - in the figure for the sake of better understanding exaggeratedly large - annular spaces 19 . 20 . 21 and 22 in the core structure layers 2 and 3 as well as the heating layers 8th . 9 ,

The reinforcing elements 16 . 17 and 18 are elongated and preferably have a substantially circular cross-section. The reinforcing elements 16 . 17 and 18 are provided with such a length and so with respect to the heating layers 8th . 9 and the core structure layers 2 . 3 arranged that they each with respect to the heating layers 8th . 9 protruding sections 25 . 26 respectively 27 . 28 have (on the reinforcing element 18 will not be discussed in more detail below, as it is not necessary to explain the following steps).

Before piercing the reinforcing elements 16 . 17 can still intermediate layers 23 . 24 on the heating layer 8th respectively 9 be applied. The intermediate layers 23 . 24 preferably have a CFRP prepreg material with in particular in comparison to the heating material of high fiber density. However, for the sake of clarity, the method will be described below without the intermediate layers 23 and 24 be further explained (therefore these are shown in the figure, only dashed).

Then there is the possibility of further intermediate layers 29 . 30 on each side facing each other 31 respectively 32 the core structure layers 2 or 3 apply. In the other intermediate layers 29 . 30 these may be, in particular, coatings, for example of duroplastic or thermoplastic material. These coatings 29 . 30 can simply be applied by means of a device (not shown) which enters the cavity 5 is moved in. As can be seen from the figure, coatings border 29 . 30 directly to the reinforcing elements 16 . 17 in areas 33 . 34 (by way of example only for the reinforcing element 16 shown).

For better understanding, the reinforcing elements 16 and 17 shown in different states of the process. The reinforcing element 16 shows the state after piercing the heating layers 8th . 9 as well as the core structure layers 2 . 3 ,

At least the protruding sections 25 ... 28 as exemplified in the section 26 shown, in the longitudinal direction of the reinforcing element 16 running fibers 35 , for example Carbon fibers, which are in a matrix 36 , For example, an epoxy resin matrix, are steeped on. The matrix 36 located at the piercing of the reinforcing element 16 in an at least partially crosslinked state with, for example, a degree of crosslinking of 60-80%, so that the reinforcing element 16 has sufficient rigidity.

Now to the protruding sections 25 . 26 of the reinforcing element 16 in the for the protruding sections 27 . 28 of the reinforcing element 17 Being able to fold shown state becomes the power source 15 activated, leaving the heating layers 8th and 9 With current flowing through, they then deliver a defined heat output.

The heating layers 8th and 9 can also be designed such that they only heat output in the region of the reinforcing elements 16 . 17 submit.

Because of the heating layers 8th . 9 heat generated softens the matrix 35 in the protruding sections 25 and 26 , Now, a force, for example by means of a single Lich schematically indicated roller 37 , on the protruding sections 25 . 26 applied, which on the heating layer 8th respectively 9 executed, so fold the protruding sections 25 . 26 on the heating layer 8th respectively 9 and come to lie on this substantially parallel to the same, as for the reinforcing element 17 shown. The protruding sections 25 . 26 become imaginary pivot points 38 respectively 39 to the heating layer 8th respectively 9 folded down. The protruding sections 27 . 28 then engage the heating layers 8th . 9 and thus also the core structure layers 2 respectively 3 for a positive connection in the cured state of the reinforcing elements 16 . 17 ,

Preferably glued in the folded state of the protruding portions 27 . 28 their matrix 35 with the matrix 9b the heating layers 8th . 9 which also softens due to the generated heat, or - in the case that the intermediate layers 23 and 24 be provided - with their matrix.

The heat input into the protruding sections 25 . 26 and the associated softening thereof leads to an increase in the degree of crosslinking in these. By way of example, this can result in a degree of crosslinking of approximately 60% during penetration of the reinforcing elements 16 . 17 increase to a degree of crosslinking of about 90%.

Because of the heating layers 8th . 9 generated heat runs the matrix 9b then, as with the reference number 40a indicated in the annulus 21 (only for this example explained in more detail) in the area of the page 6 the core structure layer 2 and closes this solid and / or fluid-tight. This process is characterized by a capillary action in the annulus 21 further supported in it.

On the other hand 31 the core structure layer 2 or the other side 32 the core structure layer 3 leads from the heating layers 8th respectively 9 generated heat causes the coating 29 respectively 30 also at least in the area adjacent to the reinforcing element 17 (see areas 33 . 34 at the reinforcing element 16 ) is crosslinked higher and thereby preferably softens so that they, as exemplified by the reference numeral 41 marked in the annulus 21 of the page 31 run into this and then from the side 31 her solid and / or fluid-tight closes.

Are all protruding sections 25 to 28 folded down, so are preferably cover layers 42 . 43 on the heating layer 8th respectively 9 or - in the event that interlayers 23 . 24 have been provided - applied to this. The cover layers 42 . 43 have fibers 44 , preferably carbon fibers, which are in a matrix 45 , in particular epoxy resin, are impregnated on. The cover layers can 42 . 43 be provided as prepreg material or dry on the heating layers 8th respectively 9 (or the intermediate layers 23 respectively 24 ) and, for example, in the infusion process with the matrix 45 be soaked. The possibility of providing as a prepreg material or the possibility of arranging the dry fiber material and introducing the matrix in the arranged state, incidentally, also for the layers described above 8th . 9 . 23 . 24 ,

In a further step, the entire arrangement shown in the figure, in particular the matrices 9b . 29 . 30 . 35 . 45 , by reactivating the power source 15 cured over a given period of time. Alternatively or additionally, the entire arrangement shown in the figure can also be introduced into an autoclave or oven in order to cure them there under pressure and / or heat.

Even though the invention with reference to preferred embodiments above It is not limited to this, but in many ways modifiable.

Especially the above process is not for the production of core composites limited.

In addition, it is noted that "A" or "an" excludes no multiplicity. It should also be noted that features or steps described with respect to one embodiment may also be used in combination with other features or steps of other described embodiments or refinements.

The The present invention provides a method for manufacturing a Structure, in particular a core composite in the aerospace sector, with following steps: First becomes a heating material on one side of a core structural material applied. In a further step, a reinforcing element introduced into the core structure material and the heating material in such a way that is the reinforcing element through the core structure material and the heating material and one over the heating material protruding Section has. After that, the heating material for at least partially softening the protruding section heated. Then the supernatant becomes Section with softened area as fulcrum to reach behind of the core structure material to form the structure. This Process is characterized in particular by the fact that the outstanding Sections essentially simultaneously - and not sequentially like in the prior art - heated can be. The resulting time savings in turn has a positive effect on the production costs.

1

structure

2

Core structure layer

3

Core structure layer

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distance

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cavity

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page

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page

8th

heating layer

9

heating layer

9a

fibers

9b

matrix

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connection

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connection

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connection

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connection

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ladder

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power source

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reinforcing element

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reinforcing element

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reinforcing element

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annulus

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annulus

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annulus

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annulus

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interlayer

24

interlayer

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protruding section

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protruding section

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protruding section

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protruding section

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Further interlayer

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Further interlayer

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page

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page

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Area

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Area

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fibers

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matrix

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roller

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pivot point

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pivot point

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liquefied matrix

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liquefied matrix

42

topcoat

43

topcoat

44

fibers

45

matrix

Claims (9)

Method for producing a structure ( 1 ), in particular a core composite in the aerospace sector, comprising the following steps: - application of a heating material ( 8th . 9 ) on one side ( 6 . 7 ) of a core structure material ( 2 . 3 ); - introducing a reinforcing element ( 16 . 17 . 18 ) into the core structure material ( 2 . 3 ) and the heating material ( 8th . 9 ) such that the reinforcing element ( 16 . 17 . 18 ) through the core structural material ( 2 . 3 ) and the heating material ( 8th . 9 ) and extends over the heating material ( 8th . 9 ) projecting section ( 25 ... 28 ) having; - heating the heating material ( 8th . 9 ) for at least partially softening the projecting portion ( 25 ... 28 ); and - reshaping the projecting section ( 25 ... 28 ) with the softened area as a fulcrum ( 38 . 39 ) to form the structure ( 1 ). Method according to claim 1, characterized in that the projecting portion ( 25 ... 28 ) is formed so that it on the heating material ( 8th . 9 ) or on an intermediate material applied thereto ( 23 . 24 ) comes to rest. Method according to claim 1 or 2, characterized in that a cover material ( 42 . 43 ) on the heating material ( 8th . 9 ) or the intermediate material ( 23 . 24 ) together with the overlapping section ( 25 ... 28 ) of the reinforcing element ( 16 . 17 . 18 ) is applied. Method according to at least one of the preceding claims, characterized in that the heating material ( 8th . 9 ), the intermediate material ( 23 . 24 ) and / or the cover material ( 42 . 43 ) a MA trix ( 9b ), which by means of the heating of the heating material ( 8th . 9 ) becomes fluid, whereby the matrix ( 9b ) in an annulus ( 19 ... 22 ) between the reinforcing element ( 16 . 17 . 18 ) and the core structure material ( 2 . 3 ) flows and thus closes tightly. Method according to at least one of the preceding claims, characterized in that on the other side ( 31 . 32 ) of the core structural material ( 2 . 3 ) at least in the region of an annular space ( 19 ... 22 ) between the reinforcing element ( 16 . 17 . 18 ) and the core structure material ( 2 . 3 ) another intermediate material ( 29 . 30 ) is applied, wherein a matrix ( 41 ) of the intermediate material ( 29 . 30 ) by heating the heating material ( 8th . 9 ) becomes fluid, whereby the matrix ( 41 ) in the annulus ( 19 ... 22 ) flows and thus closes tightly. Method according to at least one of the preceding claims, characterized in that the heating material ( 8th . 9 ), the intermediate material ( 23 . 24 ), the additional intermediate material ( 29 . 30 ), the reinforcing element ( 16 . 17 . 18 ) and / or the cover layer ( 42 . 43 ) a matrix ( 9b . 45 ), which by means of the heating of the heating material ( 8th . 9 ) is cured. Method according to at least one of the preceding claims, characterized in that at least the projecting portion ( 25 ... 28 ) of the reinforcing element ( 16 . 17 . 18 ) a only partially crosslinked thermoset material ( 36 ) and / or a thermoplastic material and / or fibers ( 35 ) having. Method according to at least one of the preceding claims, characterized in that the heating material ( 8th . 9 ) as ohmic heating material with electrical contacts ( 10 ... 13 ) for connection to a power source ( 15 ) is formed. Method according to at least one of the preceding claims, characterized in that the heating material ( 8th . 9 ) is formed of a carbon material and glass.