Display Apparatus And Method For Monitoring The Structural Integrity Of A Repair Location

Abstract

An indication device for monitoring the structural integrity of a repair location on a laminate structure, produced from a composite material, of a part of an aircraft outer skin is specified. The indication device has at least one elongate, thin indicator strip. The indicator strip is detachably applied to the outer layer of the laminate structure in the immediate vicinity of the repair location. The indicator strip is designed to indicate a predefined residual strength of an adhesive joint of a repair patch to the surrounding composite material.

Claims

1. An indication device for monitoring a structural integrity of a repair location on a laminate structure, produced from a composite material, of a part of an aircraft outer skin, wherein the indication device has at least one elongate, thin indicator strip detachably applied to an outer layer of the laminate structure in an immediate vicinity of the repair location; and wherein the indicator strip is configured to indicate a predefined residual strength of an adhesive joint of a repair patch to the surrounding composite material.

2. The indication device as claimed in claim 1, wherein the indicator strip is composed of a metal, a metal alloy or a fiber composite material.

3. The indication device as claimed in claim 2, wherein the metal comprises aluminum, titanium, steel or an alloy of one of the aforementioned metals.

4. The indication device as claimed in claim 1, wherein the indicator strip has a predefined prestress matched to a target strength to be achieved of the adhesive joint of the repair patch to surrounding composite material.

5. The indication device as claimed in claim 1, wherein the adhesive joint is brought about by an adhesive film.

6. The indication device as claimed in claim 1, wherein the indicator strip is applied to the cured adhesive joint by an adhesive.

7. The indication device as claimed in claim 6, wherein the adhesive has a higher adhesion than the adhesive film of the adhesive joint for the repair patch.

8. The indication device as claimed in claim 1, wherein the indicator strip detaches itself at least partially or is configured to be detached when a predefined residual strength of the adhesive joint is reached.

9. The indication device as claimed in claim 1, wherein the indicator strip has a predefined breaking point or breaking line.

10. The indication device as claimed in claim 1, wherein the indicator strip is applied to an application region of the adhesive joint extending beyond an extent of the repair location.

11. The indication device as claimed in claim 1, wherein the indicator strip has a constant thickness of between 0.1 mm and 0.5 mm.

12. The indication device as claimed in claim 1, wherein the indicator strip has a ratio of length to width in the range of from 1:2 to 1:10.

13. The indication device as claimed in claim 1, wherein the indicator strip is introduced into a depression of the composite material.

14. The indication device as claimed in claim 13, wherein the surface of the indicator strip is flush with the surface of the surrounding composite material.

15. A method for monitoring the structural integrity of a repair location, wherein the repair has been carried out on a laminate structure produced from a composite material, wherein the laminate structure is part of an aircraft outer skin, wherein the laminate structure is subjected to loads during a flight of the aircraft, wherein the method comprises: (a) applying an adhesive film to a repair location of a base structure of composite material, wherein the adhesive film extends on an outermost layer of composite material of the base structure at least partially beyond the repair location into a region of extent; (b) gluing a repair patch to the adhesive film at the repair location; (c) curing the adhesive joint; and (d) applying an indication device having an indicator strip to the region of extent, wherein the indicator strip is configured to indicate a predefined residual strength of the adhesive joint of the repair patch to the surrounding composite material.

Description

[0023] In the drawings, the same reference numerals generally refer to the same parts across the various views. The drawings are not necessarily true to scale; instead, the priority is generally to illustrate the principles of the invention. The following description describes various embodiments of the invention with reference to the following drawings, in which:

[0024] FIG. 1 shows a first embodiment of the indication device;

[0025] FIG. 2 shows another view of the embodiment illustrated in FIG. 1;

[0026] FIG. 3 shows another embodiment of the indication device;

[0027] FIG. 4 shows another view of the embodiment illustrated in FIG. 3;

[0028] FIGS. 5a and b show various steps of the method for applying an indication device;

[0029] FIG. 6 shows a first embodiment of an indicator strip; and

[0030] FIG. 7 shows another embodiment of an indicator strip.

[0031] The following detailed description refers to the attached drawings, which, for explanatory purposes, show specific details and embodiments in which the invention can be practiced.

[0032] The phrase “by way of example” is used herein with the meaning “serving as an example, case or illustration”. Any embodiment or refinement described herein as “by way of example” need not necessarily be construed as being preferred or advantageous over other embodiments or refinements.

[0033] In the following detailed description, reference is made to the attached drawings, which form part of said description and in which specific embodiments in which the invention can be implemented are shown for the purpose of illustration. In this regard, directional terminology such as “top”, “bottom”, “forward”, “rearward”, “front”, “rear” etc. are used with reference to the orientation of the figure(s) described. Since components of embodiments can be positioned in a number of different orientations, the directional terminology is used for illustration purposes and is in no way restrictive. It is self-evident that other embodiments can be used and that structural or logical changes can be performed without exceeding the scope of protection of the present invention. It is self-evident that the features of the various illustrative embodiments described herein can be combined with one another, unless specifically stated otherwise. The following detailed description is therefore not to be interpreted in a restrictive sense, and the scope of protection of the present invention is defined by the attached claims.

[0034] In the figures, identical or similar elements are provided with identical reference signs where expedient.

[0035] FIG. 1 shows a first embodiment of an indication device 100 for monitoring the structural integrity of a repair location 101 on a laminate structure, produced from a composite material 102, of a part of an aircraft outer skin. The indication device 100 has an elongate, thin indicator strip 110. The indicator strip is detachably applied to the outer layer of the laminate structure 102 in the immediate vicinity of the repair location 101. The indicator strip (110) is designed to indicate a predefined residual strength of an adhesive joint 103 of a repair patch 104 to the surrounding composite material 102. In order to detect the reliability of a repair of a composite material 102, the indication device 100 has an indicator strip 110, which is applied to a region of extent of the adhesive joint 103 which is extended beyond the repair point 101. When a predefined residual strength of the adhesive joint 103 is reached, the indicator strip 110 detaches itself at least partially from the adhesive joint 103. The indicator strip 110 has been applied to the adhesive joint 103 with a defined prestress and projects at least partially from the composite material 102 when detached. The embodiment of the indication device 100 which is illustrated in FIG. 1 shows the indicator strip 110 in the at least partially detached position in order to indicate that a predefined residual strength of the adhesive joint 103 has been reached and it was thus possible for the indicator strip 110 to detach itself at least partially.

[0036] FIG. 2 shows another view of the embodiment illustrated in FIG. 1, showing the indication device 100 in plan view. As can be seen in FIG. 2, the indicator strip 110 is applied to a region of the adhesive joint 103 which extends beyond the actual repair location. In the embodiment shown in FIG. 2, the indicator strip 110 has, by way of example, a circular frame surrounding the indicator strip 110. With the aid of the surrounding frame, the indicator strip can be found more easily during a visual inspection of the laminate structure of an aircraft outer skin. In another preferred embodiment, the indicator strip 110 can also be applied without this frame. In the embodiment shown in FIG. 2, the indicator strip 110 has a predefined breaking line 111. When a predefined residual strength of the adhesive joint 103 is reached, the indicator strip 110 breaks along the breaking line 111 owing to the prestress with which the indicator strip 110 is applied to the adhesive joint 103. The breaking strength of the indicator strip 110 along the breaking line 111 is preferably matched to the residual strength of the adhesive joint 103, with the result that the indicator strip 110 detaches itself when the predefined residual strength of the adhesive joint 103 is reached and breaks correspondingly easily along the breaking line 111.

[0037] FIG. 3 shows another embodiment of the indication device 200 for monitoring the structural integrity of a repair location 201 on a laminate structure, produced from a composite material 202, of a part of an aircraft outer skin. In the embodiment illustrated in FIG. 3, the indicator strip 210 is illustrated in a partially detached position. On the side of the indicator strip 210 facing the aircraft outer skin, an adhesive 212 is applied, via which the indicator strip 210 is applied to the laminate structure 202 under a predefined prestress. When a predefined residual strength of the adhesive joint 203 is reached, the indicator strip 210 detaches itself at least partially owing to the prestress and thus indicates that a predefined residual strength of the adhesive joint 203 of the repair location 201 has been reached or undershot.

[0038] FIG. 4 shows another view of the embodiment of the indication device 200 illustrated in FIG. 3, in plan view. In the embodiment shown in FIG. 4, the indicator strip 210 has a predetermined breaking point 211. In the embodiment illustrated in FIG. 4, the predetermined breaking point 211 is designed as a serrated breaking line. However, according to further embodiments (not shown), the predetermined breaking point 211 can also have any other suitable shape.

[0039] FIGS. 5a and b show various steps of the method for applying the indicator strip 310 of an indication device 300 for monitoring the structural integrity of a repair location 301 to a laminate structure produced from a composite material 302.

[0040] In the method step illustrated in FIG. 5a, a first region of the indicator strip 310, which is under a predefined prestress, is applied to the already cured adhesive joint 303 by means of an adhesive film 320. After the adhesive film 320 has cured, the further region of the indicator strip 310, which is still projecting upward, is likewise applied to the cured adhesive joint 303 by means of an adhesive film 322 and cured. After the adhesive film 322 has cured, the indicator strip 310 is applied flat to the cured adhesive 303, as shown in FIG. 5b. When a predefined residual strength of the adhesive joint 303 is reached, the indicator strip 310 at least partially detaches itself owing to the prestress and projects, for example, as in the embodiment illustrated in FIGS. 1 and 3.

[0041] FIG. 6 shows a first embodiment of an indicator strip 410. The embodiment of the indicator strip 410 shown in FIG. 6 has a constant ratio of length to width over the entire length of the indicator strip 410.

[0042] FIG. 7 shows another embodiment of an indicator strip 510. The embodiment of the indicator strip 510 shown in FIG. 7 has a different ratio of length to width at the respective ends 511, 512. The embodiments of the indicator strip 410 and 510 shown in FIGS. 6 and 7 are only two of many possible examples of how the shape of the indicator strip 410 or 510 can be formed. The indicator strip 510 preferably has a prestress and at least two regions 511, 512, wherein the indicator strip 510, as illustrated in FIGS. 5a and 5b, is first of all applied with a first region 511 having an adhesive film to a region of extent of the adhesive joint to be detected, and the further region 512 of the indicator strip is applied after the adhesive film has cured.

[0043] Although the invention has been shown and described primarily with reference to certain embodiments, it should be understood by those familiar with the art that numerous changes with regard to configuration and details can be made thereto without departing from the essence and scope of the invention as defined by the appended claims. The scope of the invention is thus determined by the appended claims and it is therefore intended that all changes which fall within the wording or the range of equivalence of the claims are included.

LIST OF REFERENCE SIGNS

[0044] 100, 200, 300, 400 indication device [0045] 101, 201 repair location [0046] 102, 202 laminate structure [0047] 103, 203, 303 adhesive joint [0048] 104, 204, 304 repair patch [0049] 110, 210, 310, 410, 510 indicator strip [0050] 111, 211 breaking line [0051] 212, 320, 312 adhesive [0052] 511, 512 regions of the indicator strip