DE102018129495A1 - Process for repairing a metal-fiber-plastic composite component - Google Patents

Abstract

A method for repairing a metal-fiber-plastic composite component (1) with a hybrid composite material, comprising at least one fiber-plastic composite material layer (3) and an associated metal layer (2), the method comprising at least the following stepsA Determining the extent of damage; B inserting a hole (4) through the hybrid composite material to the extent of the damage determined in step A); C inserting a metal piece (5) into the hole (4) at the level of the metal layer (2) and integrally connecting the metal piece ( 5) with the metal layer (2); D contouring the hole (4) following step B or C to form a conical edge contour (9) E providing a repair patch (8) corresponding to the contoured hole (4) from step D Connection to one of the steps AD and F, inserting the repair patch (8) into the contoured hole (4) and a material connection between the repair patch (8) and the metal layer t (2), as well as the repair patch (8) and the remaining material of the fiber-plastic composite material layer (3); as well as a use of the method.

Description

The present invention relates to a method for repairing a metal-fiber-plastic composite component.

In the prior art, there are some methods with which only composite materials or metals can be repaired.

The US 2007/0175967 A1 discloses a method for repairing metals using a friction stir welding method.

In the US 4,858,853 A a method for repairing curved composite surfaces is presented. The method presented here can in principle also be used to repair fiber-plastic composite components. By using this method, however, the weight of the repaired component is increased disproportionately.

The US 2014/0141190 A1 and the US 8,475,615 B2 each disclose a method for repairing special composite material components. A repair of fiber-plastic composite components is not disclosed or described here.

The US 5,868,886 A discloses another method of repairing composite material components by using a Z-pin in a repair patch connection, resulting in increased stress around the Z-pin holes. An application to the repair of fiber-plastic composite components is not suggested.

In the area of fiber-plastic composite material components, which are formed as a connection from fiber composite material layers and metal layers, metal pieces are supplemented in the event of damage using mechanical connections such as rivets or screws. Although the strength can be restored quickly, the weight of the component is greatly increased and the strength is not permanent, but the security of the connection and thus the component decreases after a short time.

Starting from the aforementioned prior art and the problems outlined, it is therefore the object of the present invention to provide a method for repairing a metal-fiber-plastic composite component which ensures high strength of the repaired component over a longer period of time and no excessive weight increase has the consequence.

The present invention solves this problem by a method having the features of claim 1.

Advantageous embodiments of the method are the subject of the dependent claims.

A method according to the invention serves to repair a metal-fiber-plastic composite component with a composite material.

Said component can consist entirely of the hybrid composite or only in sections of the said hybrid composite, e.g. as a plate-shaped insert in a frame.

The hybrid composite material comprises at least one fiber-plastic composite material layer, hereinafter also called FKV material layer, and a metal layer connected to it. Preferably only a single metal layer, e.g. a metal sheet used. The two layers are arranged directly one above the other. The sequence of the layers defines a so-called stacking direction.

The process comprises at least the following steps:

A determination of the extent of damage;

First, the damage status of the component is determined. In the simplest case, this can be done by visual inspection. However, it is advisable, particularly to find invisible damage in the FKV material, to carry out a non-destructive test, preferably as part of an ultrasound analysis, infrared thermography and / or shearography, on the component.

B inserting a hole through the hybrid composite to the extent of the damage determined in step A);

After determining the extent of the damage, a hole is inserted in the hybrid composite. This should be done in the scope of the damage determined and ideally also include the invisible damage in the FKV material. The hole must be dimensioned accordingly.

An elliptical hole is recommended for structural reasons. The configuration of the hole can advantageously be a stepped hole. The hole can be inserted, for example, in such a way that between the edge of the hole and the fiber-plastic composite material there is an uncoated free area on the surface of the Metal layer is arranged, which has a radial extension to the edge of the hole of at least 5 mm, preferably at least 8 mm. This serves to protect the FKV material from welding heat in the subsequent step.

C Inserting a piece of metal into the hole at the level of the metal layer and integrally connecting the piece of metal with the metal layer.

Many variants can be used for the material bond, e.g. metal-metal bonding can also be used. However, welding between the metal piece and the metal layer is particularly preferred, as a result of which a very stable connection can be created, in particular when the weld seam is rotating.

At the same time, the weld seam is also an indication of the application of the method according to the invention when a fiber-plastic composite component is present.

D Contour the hole after step B or C to form a conical edge contour

The hole can be contoured in a subsequent step. This can also be done before the metal piece is inserted, but should there be defects in the FKV material due to welding heat, this material can advantageously be removed as part of the contouring.

E Provide a repair patch corresponding to the hole contoured from step D following one of steps A-D

The method further comprises providing a repair patch which corresponds to the hole from step D. Due to the progressing automation, it is possible to plan the extent of the contouring of the hole in step D and accordingly to produce a corresponding repair patch before the actual step D or at the same time as the contouring in step D. Among other things, this saves Time.

In order to enable the possibility of a low-tolerance repair and, if necessary, to compensate for material damage due to the welding process during the contouring, the repair patch can also be produced only after the contouring in step D.

F insertion of the repair patch into the contoured hole and integral connection between the repair patch and the metal layer, as well as the repair patch and the remaining material of the fiber-plastic composite material layer and the metal layer.

The cohesive connection can be achieved in this case with an adhesive or by loosening the material of the repair patch, e.g. by spraying with solvent.

Further advantageous embodiments of the method are the subject of the dependent claims.

It is advantageous if the repair patch is made of a thermosetting fiber-plastic composite material, provided that the fiber-plastic composite material layer of the hybrid composite material is designed as a thermosetting material layer.

Alternatively, the repair patch can advantageously be formed from a thermoplastic fiber-plastic composite material, provided that the fiber-plastic composite material layer of the hybrid composite material is designed as a thermoplastic material layer.

The repair patch and the fiber-plastic composite material layer of the hybrid composite material can particularly preferably be formed from the same material.

The metal piece and the metal layer can also advantageously be made from the same material.

The conical edge contour can have an angle of 3-8 ° to accommodate shear stress increases and to maximize the contact surface.

The repair patch can be provided in a device with a molding tool, preferably with a single-shell molding tool, the molding tool having a contour in the shape of the hole.

The device can have a cover, in particular a vacuum cover, for covering the contour. A corresponding possibility for vacuum generation, e.g. a vacuum pump in a chamber between the contour and the cover can be part of the device.

Preferably, the cover or the mold can have a connection for a vacuum line, e.g. a vacuum pump.

Furthermore, the use of the method for repairing a metal-fiber-plastic composite component is in accordance with the invention, the metal-fiber-plastic composite component, preferably as impact protection, in the field of automobile construction, aerospace, wind energy plants, is used by rail systems, passenger transport vehicles and / or in the sports industry.

The method can particularly preferably be applied to an assembled metal-fiber-plastic composite component without the component having to be dismantled for repair.

Further advantages, features and details of the invention result from the following description, in which an embodiment of the invention is explained in more detail with reference to the drawing. A person skilled in the art will expediently also consider the features disclosed in combination in the drawing, the description and the claims in combination and combine them into useful further combinations.

• 1 schematische Darstellung eines Defekts in einem Metall-Faser-Kunststoff- Verbund-Bauteil;
• 2a, 2b schematische Darstellung eines Zwischenproduktes eines zweiten und dritten Verfahrensschrittes;
• 3a, 3b schematische Darstellung der Dimensionierung eines Reparaturflickens zur Verwendung in einem weiteren Verfahrensschritt;
• 4a, 4b Darstellung von Varianten zum Bereitstellen des Reparaturflickens;
• 5 Darstellung des Verbindens des Reparaturflickens mit einem zu reparierenden Faser-Kunststoff-Verbund-Bauteil und
• 6 repariertes Faser-Kunststoff-Verbundbauteil.

Show it:

• 1 schematic representation of a defect in a metal-fiber-plastic composite component;
• 2a , 2 B schematic representation of an intermediate product of a second and third process step;
• 3a , 3b schematic representation of the dimensioning of a repair patch for use in a further process step;
• 4a , 4b Presentation of variants for providing the repair patch;
• 5 Representation of connecting the repair patch to a fiber-plastic composite component to be repaired and
• 6 repaired fiber-plastic composite component.

The following procedure describes the restoration of a metal-fiber-plastic composite component from a hybrid composite material. The hybrid composite material preferably comprises a fiber-plastic composite (FKV) comprising at least one fiber composite material layer. The hybrid composite material further comprises a metal layer.

The term hybrid composite material describes, in particular, a metal-plastic composite structure which has a flat, cohesive connection. The hybrid composite structure can be constructed in a so-called mixed construction. The integral connection can preferably be achieved by adhesive or by matrix adhesion.

All weldable metals can be used as the metal layer. Steel and / or aluminum are particularly preferred. These can be provided in the form of metal sheets. The preferred layer thickness of the metal layer can preferably be between 0.3 mm to 2 mm.

The fiber plastic composite material (FKV) comprises fibers which are embedded in a plastic matrix and / or are impregnated with this plastic matrix.

The FKV material layer can be constructed in several layers. The FKV material layer has a preferred layer thickness between 1.5 mm and 6.0 mm.

Glass fibers, aramid fibers and / or carbon fibers can preferably be used as fibers. However, other fiber materials are also possible. The preferred average fiber length is at least 5 mm.

For short fibers, lengths of at least 5 mm can preferably be used. However, unidirectional fibers can also be used, including unidirectional continuous fibers.

The plastic matrix comprises thermoplastic and thermosetting plastics, e.g. Polypropylene, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), cyanate ester, polyimide polyamide and / or epoxy materials.

The metal-fiber-plastic composite components described above, in particular comprising at least one FKV material layer and one metal layer, are of heterogeneous construction and have anisotropic properties.

Typical areas of application for the above-described components are, for example, automobile construction, aerospace, wind energy plants, railway systems and / or the sports industry. The above-mentioned components are used as lightweight hybrid composite materials, in particular in electromobility applications.

A particularly preferred area of application within the aforementioned areas of application is impact protection, e.g. in applications such as bumpers or the like.

In the event of damage, for example in the event of impacts or impacts on the material, metal-fiber-plastic composite components have defects which are not included are visible to the naked eye. Such defects can include matrix cracks, detachment between the composite materials, delamination between the FKV material layer and the metal layer or fiber breaks within the FKV material layer.

The aim of the method according to the invention is to restore the metal-fiber-plastic composite component.

To detect these defects, the extent of damage can be determined in a first step A of the method by means of a non-destructive test. Ultrasound analysis, infrared thermography and / or shearography can preferably be used for non-destructive testing. Damage patterns can be generated with regard to the scope of the defect.

1 shows a typical defect in a plate-shaped metal-fiber-plastic composite component 1 . As previously described, the metal-fiber-plastic composite component has a metal layer 2nd and at least one FKV material layer 3rd on. This in 1 Component shown in detail extends in the X, Y and Z directions, the X direction defining a width, the Y direction defining a length and the Z direction defining a depth. The depth corresponds to the stacking direction of the material layers 2nd and 3rd .

Damage to the metal layer 2nd extends as visible damage, eg as a deformation, in the Y direction 2a and in the X direction 2 B .

Damage to the FKV material layer 3rd extends as visible damage in the Y direction 2a ' and in the X direction 2 B' .

How out 1 the extension is recognizable 2a ' and 2 B' The visible damage to the FKV material is less than the extent of the visible damage 2a and 2 B the metal layer. However, it can also happen that the extension 2a ' and 2 B' the visible damage to the FKV material is greater than the extent of the visible damage 2a and 2 B the metal layer.

The difference Δa ' and Δb ' the aforementioned extensions in the X and Y directions are in 1 invisible internal damage between the FKV material layer 3rd and the metal layer 2nd .

After determining the extent of damage in step A, including the invisible damage, a hole can be made in step B. 4th be drilled into the metal-fiber-plastic composite component. The hole can preferably be elliptical.

The hole can, as in 2nd shown with a defect with 2a> 2a ', 2b>2b' and 2a> 2b, with a major axis dimension 2a and a minor axis dimension 2 B be drilled into the hybrid material.

The main axis dimension corresponds to the extension 2a visible damage to the metal layer 2nd in the Y direction or the sum of the extent of the visible coating 2a ' and the invisible damage Δa ' the FKV material layer 3rd in the Y direction.

The X-axis dimensioning of the hole can preferably have the length of 2b if 2b> 2b 'or vice versa. The Y-axis dimensioning can preferably be the length 2a if 2a> 2a 'or vice versa. If the x-axis length is greater than the y-axis length, then the major axis of the elliptical hole lies in the x-axis or vice versa.

However, the dimensioning of the hole always depends on the extent of the visible metal layer, the FKV material layer and the invisible damage to the FKV material layer.

If 2a '+ Δa'> 2a, the non-visible damage of the FKV material surrounding the hole determined in step A must be completely removed. In addition, the FKV material should ideally be removed from the hole up to at least 5 mm, preferably at least 8 mm. The same applies to the case that 2a '+ Δa' <2a. Here, too, the distance should be at least 5 mm, preferably 8 mm.

The same applies to dimensioning the borehole in the minor axis direction.

A new undamaged piece of metal 5 can then in a step C to the dimensions of the hole 4th , in particular the elliptical hole. This can be done, for example, by cutting or punching.

The new metal piece preferably corresponds to the material of the remaining metal layer 2nd with the hole 4th . For the new metal piece, the same type of steel can preferably be used as for the metal layer 2nd be used

The layer thickness, in particular the sheet thickness, of the metal piece 5 corresponds to the layer thickness or sheet thickness of the metal layer 2nd .

The piece of metal 5 will be inside the hole 4th positioned and can be welded to form a weld 6 cohesive with the metal layer 2nd get connected. The welding is from the uncoated side 7 the metal layer 2nd to execute.

In step D, the hole is then prepared 4th on the use of a FKV repair patch 8th . The prepared hole 4th and the repair patch 8th are among others in 5 shown. The dimensioning of the repair patch 8th is also in 3a and 3b shown.

For this the hole 4th with a preferably circumferential, conical edge contour extending in the Z direction 9 Mistake. The cross-section of the edge of the hole is thus based on the interface 10th with the metal layer 3rd larger towards the uncoated side of the FKV material layer. The angle α the conical edge contour 9 starting from the interface 10th is preferably 3-8 °. The conical edge contour 9 serves to compensate for shear stress increases and to maximize contact area.

The load is thus transferred to the plane and therefore not or only to a small extent to the fibers.

The one in the hole 4th repair patches to be used 8th points one to the hole 4th corresponding conical edge contour 11 on.

The repair patch can be made available in a step E, for example, by creating a molding tool, in particular a single-shell molding tool. Optionally, the contour of the conical hole 4th be scanned. However, the dimension of the hole may already be known due to the previous manufacturing steps.

The molding tool can then be made by a generative manufacturing process, e.g. 3D printing.

Alternatively there is the possibility of contouring the hole in a molding tool, e.g. cut into a plate. This can e.g. by means of a laser.

Other variants for manufacturing a mold are also suitable.

The mold 12 can be treated with a mold release agent to prevent the repair patch from sticking and to ensure safe removal from the mold.

In 4a and 4b are two ways to make the repair patch 8th in step E within a device 20th , 30th comprising the mold 12 shown.

A semi-finished fiber-plastic product 13 fibers pre-impregnated with plastic resin, also called "prepreg", are inserted into the mold 12 inserted which is a contour 14 analogous to the hole 4th having.

The plastic resin of the semi-finished product 13 can still polymerize and thereby combine with the fibers to form a composite material.

The device 20th in 4a also has a cover 15 e.g., in the form of a vacuum hood or vacuum film, which is media-tight over the contour 14 of the mold 12 forming a vacuum chamber 18th is arranged.

For this, the edge is around the contour 14 a seal around 16 , for example in the form of a sealing compound.

Furthermore, the cover 15 an infusion port 17th for resin infusion into the vacuum chamber 18th on and a vacuum pump 19th for extracting air from the vacuum chamber 18th .

A tear-open fabric 21st is inside the vacuum chamber 18th arranged. It serves to create a smooth surface of the FKV layer after the repair. As a result, the repaired surface does not require any further post-processing after the tear film has been removed. Furthermore is inside the vacuum chamber 18th a perforated fabric 22 arranged. This serves as a flow aid and enables the flow rate of the plastic to be increased.

In the 4a shown device 20th enables in particular the formation of a thermoset repair patch 8th . The resin used is a thermosetting polymer mixed with other curing agents and through the infusion opening 17th into the device 20th can be injected. The molecules crosslink and form a fixed, preformed repair patch. Curing can be done either at room temperature or in an oven.

The device 30th in 4b enables the provision of a thermoplastic repair patch 8th . However, there is also the possibility of thermoset repair patches depending on the design of the semi-finished product 33 to realize.

After positioning the semi-finished product 33 in the contour 35 of the mold 34 is this with a cover 31 , preferably with the formation of a chamber 32 , Mistake. Again, the cover 31 with sealing element on the edge 36 optionally be designed as a vacuum hood. Repairing under vacuum is only an option with this variant.

A subsequent thermal treatment can be carried out in an oven. The resin of the semi-finished product hardens and takes the shape of the contour 34 at.

In a step F, the repair patch is then arranged 33 inside the conical hole.

In the case of a FKV material layer to be repaired based on a thermosetting material, the repair patch should also consist of a thermosetting material.

Similarly, in the case of a FKV material layer to be repaired based on a thermoplastic material, the repair patch should also consist of a thermoplastic material.

In the case of FKV material layers with a known composition, the same material should preferably be used as the repair patch material or, alternatively, a repair patch with higher strength and rigidity should be used.

Finally, the repair patch provided 8th with the remaining FKV material layer 2nd get connected. This can be done, for example, at room temperature using a construction adhesive 23 respectively.

The above-described method is characterized in particular by the fact that the weight of the component does not increase disproportionately strongly during the restoration or repair and that the repaired metal-fiber-plastic composite component is guaranteed to be permanent.

The process enables the strength of the component to be produced while at the same time ensuring structural security over a long period. The useful life of the corresponding component is extended overall.

The process also enables fixed components to be repaired without disassembly, provided the metal layer and the FKV material layer are accessible for processing.

Compared to previously known repair methods in this area of application, the repaired component has improved mechanical properties.

Finally, the aforementioned method according to the invention enables a reduction in waste of components in mixed construction with FKV materials and metals and thus a conservation of resources. The process thus contributes to protecting the environment.

Reference symbol list

1

Metal-fiber-plastic composite component

2nd

Metal layer

3rd

FKV material layer

4th

hole

5

Piece of metal

6

Weld

7

Uncoated side

8th

FKV repair patch

9

Conical edge contour

10th

interface

11

Conical edge contour

12

Molding tool

13

FKV semi-finished products

14

contour

15

cover

16

poetry

17th

Infusion port

18th

Vacuum chamber

19th

Vacuum pump

20th

contraption

21st

Tear-off fabric

22

Perforated fabric / flow aid

23

Construction adhesive

30th

contraption

31

cover

32

chamber

33

FKV semi-finished products

34

Molding tool

35

contour

36

Sealing element

2a

Extension visible damage in the metal layer in the Y direction

2a '

Extension visible damage in the FKV layer in the Y direction

2 B

Extension visible damage in the metal layer in the X direction

2 B'

Extension visible damage in the FKV layer in the X direction

Δa '

Extension of invisible damage in the FKV layer in the Y direction

Δb '

Extension of invisible damage in the FKV layer in the X direction

α

Angle of the conical edge contour 9

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2007/0175967 A1 [0003]
• US 4858853 A [0004]
• US 2014/0141190 A1 [0005]
• US 8475615 B2 [0005]
• US 5868886 A [0006]

Claims (15)

Method for repairing a metal-fiber-plastic composite component (1) with a hybrid composite material, comprising at least one fiber-plastic composite material layer (3) and an associated metal layer (2), the method comprising at least the following steps A determination of the extent of damage; B inserting a hole (4) through the hybrid composite to the extent of the damage determined in step A); C inserting a metal piece (5) into the hole (4) at the level of the metal layer (2) and integrally connecting the metal piece (5) with the metal layer (2); D contouring the hole (4) following step B or C to form a conical edge contour (9) E Provide a repair patch (8) corresponding to the contoured hole (4) from step D following one of the steps A-D and F insertion of the repair patch (8) into the contoured hole (4) and integral connection between the repair patch (8) and the metal layer (2), as well as the repair patch (8) and the remaining material of the fiber-plastic composite material layer (3 ). Procedure according to Claim 1 , characterized in that the repair patch (8) is made of a thermosetting fiber-plastic composite material, provided that the fiber-plastic composite material layer (3) of the hybrid composite material is designed as a thermosetting material layer. Procedure according to Claim 1 , characterized in that the repair patch (8) is formed from a thermoplastic fiber-plastic composite material, provided that the fiber-plastic composite material layer (3) of the hybrid composite material is designed as a thermoplastic material layer. Method according to one of the preceding claims, characterized in that the repair patch (8) and the fiber-plastic composite material layer (3) of the hybrid composite material are formed from the same material. Method according to one of the preceding claims, characterized in that the metal piece (5) and the metal layer (2) are made of the same material. Method according to one of the preceding claims, characterized in that the extent of damage is determined according to step A in the context of a non-destructive test, preferably in the context of an ultrasound analysis, infrared thermography and / or shearography. Method according to one of the preceding claims, characterized in that the hole (4) inserted in step B is designed as an elliptical hole. Method according to one of the preceding claims, characterized in that the insertion of the hole (4) takes place in such a way that an uncoated free area (b ') on the surface of the. Between the edge of the hole (4) and the fiber-plastic composite material Metal layer (2) is arranged, which has a radial extension to the edge of the hole (4) of at least 5 mm, preferably at least 8 mm. Method according to one of the preceding claims, characterized in that the insertion of the metal piece (5) according to step C is carried out by welding to the metal layer (2). Method according to one of the preceding claims, characterized in that the conical edge contour (9) has an angle of 3-8 °. Method according to one of the preceding claims, characterized in that the repair patch (8) is provided in a device (20, 30) with a molding tool (12, 34), preferably a single-shell molding tool, the molding tool (12, 34) has a contour (14, 35) in the form of the hole (4). Method according to one of the preceding claims, characterized in that the device (20, 30) has a cover (15, 31), in particular a vacuum cover, for covering the contour (14, 35). Method according to one of the preceding claims, characterized in that the contouring of the hole (4) according to step D takes place after the insertion of the metal piece (5) in step C. Method according to one of the preceding claims, characterized in that the repair patch (8) is provided after the hole (4) has been formed in step D. Use of the method for repairing a metal-fiber-plastic composite component (1), the metal-fiber-plastic composite component (1), preferably as an impact protection, in the field of automotive engineering, aerospace Wind turbines, railway systems, of Passenger vehicles and / or used in the sports industry.

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