Adhesive film and arrangement and method for verifying an adhesive attachment

Abstract

An adhesive film and arrangement and method for verifying an adhesive attachment. A mechanical strength of adhesive film structure is matched to a target binding force of a bond produced using the film where when the film is pulled from the substrate or a material layer with peeling stress on the bond for verification of adhesive attachment, the film fails with exceedance of the mechanical strength of the structure when the strength of the bond attains or exceeds the target binding force, and the adhesive film when pulled apart does not fail when bond strength does not attain target binding force. An arrangement is disclosed for verification of adhesive attachment, having a substrate, a component bonded to the substrate by an adhesive film, and at least one test section. The test section is formed by projection of the film across an edge of the component bonded to the substrate, the projection being bonded to regions of the substrate.

Claims

1. An adhesive film for a structural adhesive bond to a substrate, the adhesive film having a structure, the structure of the adhesive film taking a form of a carrier structure of the adhesive film, the carrier structure being formed by a textile fabric, and where, at least in a subregion of the adhesive film, a mechanical strength of the structure has been matched to a predefined target binding force of a bond produced using the adhesive film such that, after completion of the bond, when the adhesive film is pulled away from the substrate or from a material layer with peeling stress on the bond for verification of the adhesive attachment to the substrate or to the material layer, the adhesive film fails with exceedance of the mechanical strength of the structure when strength of the bond attains or exceeds the target binding force, and the adhesive film when pulled apart does not fail at least in the subregion when strength of the bond does not attain the target binding force.

2. The adhesive film according to claim 1, wherein, at least in a subarea of the adhesive film, the structure has been formed with an additional reinforcing component, where the additional reinforcing component has been applied to a starting adhesive film to form the adhesive film or has been introduced into the starting adhesive film, and wherein the mechanical strength matched to the target binding force is a mechanical strength of the structure including the additional reinforcing component.

3. A method of verifying adhesive attachment in a structural adhesive bond to a substrate produced according to claim 1 using an adhesive film having a structure, the structure of the adhesive film taking a form of a carrier structure of the adhesive film, the carrier structure being formed by a textile fabric, wherein, after completion of a bond produced using the adhesive film, for verification of adhesive attachment to the substrate and/or to a material layer, a test section formed by a section of the adhesive film is pulled away from the substrate and/or from the material layer with peeling stress on the bond.

4. An arrangement for verification of an adhesive attachment, having a substrate, a component bonded to the substrate by an adhesive film to form a structural adhesive bond, and at least one test section; where the test section is formed by a projection of the adhesive film that extends at least beyond part of an edge of the component bonded to the substrate and the projection is bonded to the substrate in some regions; and wherein a mechanical strength of the test section, at least in a subregion of the test section, is matched to a predefined target binding force of a bond produced using the adhesive film such that, after completion of the bond, when the test section is pulled away from the substrate with peeling stress on the bond, the test section breaks off with exceedance of the mechanical strength thereof when strength of the bond attains or exceeds the target binding force and the test section, when pulled apart, does not break off, at least in the subregion, when strength of the bond does not attain the target binding force.

5. The arrangement according to claim 4, wherein the adhesive film has a structure and at least in the subregion of the test section a mechanical strength of the structure is matched to the target binding force of the bond produced using the adhesive film such that, when the test section is pulled off, the adhesive film fails with exceedance of the mechanical strength of the structure when strength of the bond attains or exceeds the target binding force, and the adhesive film when pulled apart does not fail at least in the subregion when strength of the bond does not attain the target binding force.

6. The arrangement according to claim 4, wherein the arrangement also has an intermediate element spaced apart from the edge of the component bonded to the substrate, and the projection extends over regions of the intermediate element, such that the intermediate element is in regions between the projection and the substrate, where the projection is bonded to the substrate between the edge of the component bonded to the substrate and the intermediate element, and where the projection is readily detachable from the intermediate element.

7. The arrangement according to claim 4, comprising an additional reinforcing component at least in a first subarea of the test section.

8. The arrangement according to claim 7, wherein the arrangement also has an intermediate element spaced apart from the edge of the component bonded to the substrate, and the projection extends over regions of the intermediate element such that the intermediate element is in regions between the projection and the substrate, where the projection is bonded to the substrate between the edge of the component bonded to the substrate and the intermediate element, and where the projection is readily detachable from the intermediate element, and wherein the first subarea ends between the intermediate element and the component bonded to the substrate before reaching the component bonded to the substrate.

9. The arrangement according to claim 7, wherein the arrangement also has an intermediate element spaced apart from the edge of the component bonded to the substrate, and the projection extends over regions of the intermediate element such that the intermediate element is in regions between the projection and the substrate, where the projection is bonded to the substrate between the edge of the component bonded to the substrate and the intermediate element, and where the projection is readily detachable from the intermediate element, and wherein the first subarea overlaps with at least sections of the intermediate element and extends across a section of an edge of the intermediate element.

10. The arrangement according to claim 4, wherein an additional material layer with elevated breaking strength is disposed on the projection in a second subarea of the test section.

11. The arrangement according to claim 10, wherein the arrangement also has an intermediate element spaced apart from the edge of the component bonded to the substrate, and the projection extends over regions of the intermediate element such that the intermediate element is in regions between the projection and the substrate, where the projection is bonded to the substrate between the edge of the component bonded to the substrate and the intermediate element, and where the projection is readily detachable from the intermediate element, and wherein the second subarea ends between the intermediate element and the component bonded to the substrate before reaching the component bonded to the substrate, and wherein the second subarea overlaps with at least sections of the intermediate element and extends across a section of an edge of the intermediate element.

12. The arrangement according to claim 4, comprising an additional reinforcing component at least in a first subarea of the test section, wherein an additional material layer with elevated breaking strength is disposed on the projection in a second subarea of the test section, and wherein the first subarea overlaps with sections of the second subarea, the first subarea extends across one end of the second subarea and the first subarea ends between the end of the second subarea and the adhesive-bonded component before reaching the adhesive-bonded component.

13. The arrangement according to claim 4, wherein the intermediate element comprises a release film, and/or wherein the component bonded to the substrate comprises a laminate or a laminate ply.

14. A method of verifying an adhesive attachment, the method comprising: arranging a substrate, a component to be bonded to the substrate and an adhesive film such that a section of the adhesive film is arranged between the substrate and the component to establish a structural adhesive bond and the adhesive film extends over at least part of an edge of the component and forms a projection; curing at least the adhesive film; and peeling off a test section formed by the projection of the adhesive film that extends at least across part of the edge of the component from the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure herein is elucidated in detail hereinafter with reference to the working examples specified in the schematic figures. In the example figures:

(2) FIG. 1 is a top view (a) and a section view (b) of an arrangement in a first working example of the disclosure herein;

(3) FIG. 2 is a top view (a) and a section view (b) of an arrangement in a second working example of the disclosure herein;

(4) FIG. 3 is a top view (a) and a section view (b) of an arrangement in a third working example of the disclosure herein;

(5) FIG. 4 is a top view (a) and a section view (b) of an arrangement in a fourth working example of the disclosure herein;

(6) FIG. 5 is an illustrative step of peeling-off a test section in an arrangement according to the first working example by a rolling device, shown in a section view of the arrangement;

(7) FIG. 6 is a top view (a) and a section view (b) of an arrangement in a fifth working example of the disclosure herein;

(8) FIG. 7 is a detail of a section view of an arrangement in a sixth working example of the disclosure herein; and

(9) FIG. 8 is a detail of a section view of an arrangement in a seventh working example of the disclosure herein.

DETAILED DESCRIPTION

(10) The appended figures are intended to impart further understanding of the embodiments of the disclosure herein. They illustrate embodiments and serve to elucidate principles and concepts of the disclosure herein in connection with the description. Other embodiments and many of the advantages mentioned will be apparent with regard to the drawings. The elements of the drawings are not necessarily to scale with respect to one another.

(11) In the figures, elements, features and components that are identical, have the same function and the same effect—unless stated otherwise—are each given the same reference numerals.

(12) FIG. 1 shows an arrangement 10 for verifying an adhesive attachment in a first working example. A component 50 has been bonded to a substrate 20, where, in FIG. 1, component 50 has been bonded by way of example to the upper surface 22 of the substrate 20 in FIG. 1. The bonding of component 50 to substrate 20 was achieved in the arrangement 10 by an adhesive film 30. For this purpose, the adhesive film 30 was disposed between component 50 and substrate 20. Thus, by the adhesive film 30 a structural adhesive bond 40 has been formed between component 50 and substrate 20.

(13) Substrate 20 in the first working example is, by way of example, a fiber composite component which is to be repaired in an aerospace vehicle, for example an aircraft. Substrate 20 has been formed by a fiber composite material, especially a fiber-reinforced polymer material, having a matrix and reinforcing fibers. The matrix may be formed, for example, by an epoxy resin, and the reinforcing fibers provided may be carbon fibers or glass fibers.

(14) In an area 21 for accommodation of component 50 in the form of a repair “patch”, the substrate 20 has been provided with a flat recess that has preferably been introduced by grinding. The recess in the area 21 is of a size corresponding to the size of component 50 and enables the accommodation of component 50 together with the adhesive film 30, for example in such a way that component 50 does not protrude significantly above the surface of substrate 20, if at all, at the side of component 50. Component 50 in FIG. 1 has been provided with a taper by way of example in the region of an edge 51 of component 50. In the first working example, component 50 is circular, but may be differently shaped in variants.

(15) The adhesive film 30 extends along both sides of component 50 across an assigned part 52 of the edge 51 of component 50 in each case, as a result of which a projection 35 in the form of a strip of the adhesive film 30 has been formed in the region of each of the opposite sides of component 50.

(16) The arrangement 10 also has two intermediate elements 70 disposed on the substrate 20. Component 50 is disposed between the intermediate elements 70, by way of example in about the middle in FIG. 1, in such a way that each of the intermediate elements 70 is spaced apart from the edge 51. A gap 72 has thus been provided between each of the intermediate elements 70 and component 50. The projection 35 extends in each case by its distal end, viewed from the component 50, over regions of the intermediate element 70, where the projection 35 ends in each case at the assigned intermediate element 70. The intermediate element 70 is in regions in each case between the assigned projection 35 and the substrate 20. Between the edge 51 of the component 50 and the assigned intermediate element 70, the projection 35 has been bonded to the substrate 20 in each case in a region 36 thereof. In FIG. 1, each projection 35 as a section of the adhesive film 30 forms a test section 60 that ends on the intermediate element 70 at an end 69.

(17) The adhesive film 30 has an adhesive and an internal support structure not shown in FIG. 1, which may be formed by a textile fabric, especially a nonwoven fabric, a woven fabric or a knitted fabric. The support structure enables appropriate handling of the adhesive film 30 and ensures that the adhesive film 30 still retains a minimum thickness even when pressure is applied thereto. In this way, a sufficient thickness of an adhesive layer is ensured. The adhesive may be a curable adhesive, including an epoxy resin, for example.

(18) A mechanical strength of the support structure, in the adhesive film 30 overall, has been matched to a predefined target binding force of a bond K produced using the adhesive film 30 to form the structural adhesive bond 40. The matching has been done in such a way that—after completion of the bond K—when the adhesive film 30 is pulled away from substrate 20 by peeling stress on the bond K for verification of the adhesive attachment to the substrate 20, the adhesive film 30, comprising the support structure and the adhesive, fails with exceedance of the mechanical strength of the support structure in combination with the adhesive when the strength of the bond K attains or exceeds the target binding force. However, the adhesive film 30 does not fail, i.e. does not break off, when the strength of the bond K does not attain the target binding force—in this case there is continued peeling-off of the adhesive film 30.

(19) The mechanical strength may, for example, be a breaking strength or tensile strength of the support structure which may be selected in such a way that the support structure of the adhesive film 30 and hence the adhesive film 30 fail on attainment or exceedance of the target binding force. In variants, the adhesive film 30 may, however fail under the action of fracture mechanisms that are active in the combination of adhesive and support structure present in the adhesive film 30 and derive, for example, from bending, when the target binding force of the bond K is attained or exceeded. In such a case, the matched mechanical strength may be a fracture strength or flexural strength or a differently defined mechanical strength.

(20) In order to complete the bond K, after the intermediate elements 70, the adhesive film 30 and the component 50 have been disposed on the substrate 20, the adhesive film 30 is cured. In the first working example, component 50 is preferably uncured or incompletely cured, such that it likewise cures or cures further in the curing of the adhesive film 30. The curing can be effected, for example, under a vacuum setup with local heating. In one variant of the first working example, component 50, however, may already have cured before the adhesive film 30 is arranged between component 50 and substrate 20 and the adhesive film 30 is cured.

(21) In order subsequently to test the adhesive attachment in the region of the bond K, after completion of the bond K, the test section 60 is detached from the intermediate element 70 at its end 69 and pulled away from the substrate 20 with peeling stress on the bond K. In this way, the bond K is stressed for testing purposes in the region 36. With the aid of the intermediate element 70, for this purpose, an initial crack is provided, and the detachment of the end 69 is additionally enabled in order to be able to grip the test section 60 at its end 69. The intermediate element 70 in each case takes the form of a release film, as a result of which the projection 35 is readily detachable from the intermediate element 70 at the end 69 of the test section 60.

(22) The pulling-away of the test section 60 is shown in schematic form for the first working example in FIG. 5 and is effected essentially at right angles to component 50. Peeling forces are generated here that stress the bond K. In FIG. 5 a force is applied to pull away the test section 60 by a roller device 90. In this case, the end 69 of the test section 60 can be held at the circumference of a roller body 91 of the roller device 90 and pulled away with rotation of the roller body 91, indicated in FIG. 5 by the arrow R. Alternatively, it is possible to grip the end 69 of the test section 60 by hand or by tongs (not shown) and to pull away the test section 60.

(23) With the aid of the adhesive film 30, in the arrangement 10, the mechanical strength of the test section 60 is adjusted in such a way that the test section 60 breaks off with exceedance of the mechanical strength thereof, for example a tear strength and/or breaking strength, when the binding force of the bond K is sufficiently great and hence attains or exceeds a predefined target binding force. Since the test section 60, given sufficient quality of the bond K, already breaks off before reaching component 50, and preferably already breaks off at an intended break site or intended fracture site S at or close to an edge 71 of the intermediate element 70, the adhesive bond 40 of substrate 20 and component 50 is not impaired when the bond K is sufficiently good. The edge 71, viewed from component 50, is a proximal edge of the intermediate element 70. However, the test section 60 does not break off at the intended break site S when the binding force of the bond K is too low and the target binding force is therefore not attained, but continues to peel off in the region 36.

(24) The utilization of the adhesive film 30 for the verification of adhesive attachment in the region of the bond K enables simple verification as to whether the predefined target binding force is attained, and avoids the production of separate samples and waiting for laboratory results. Moreover, testing by the test section 60 involves the substrate 20, i.e., in the case of the repair shown in FIG. 1, the fiber composite component already in use, and its previous history. The test section 60 with the projection 35 is also subjected to the same method steps as executed for production of the bond K of component 50 to the substrate 20. The test result thus enables, in an improved manner, a conclusion as to the quality of the adhesive bond 40.

(25) In the first working example, demonstration of adhesive attachment is thus enabled by a projection 35 which forms a test section 60, and the mechanical strength of which is matched to the minimum adhesion force of the bond K. A simple, rapid test of the adhesive attachment between the surface 22 of the substrate 20 and the component 50 is possible by the adhesive film 30.

(26) The test section 60 with the intermediate element 70 in FIG. 1 can also be referred to as a “process control specimen” or “PCS”. In the Figures, one of these process control specimens in each case is emphasized with the aid of a dotted line. In the first working example, two equivalent test sections 60 and hence two PCSs are provided. The adhesive attachment can thus be tested twice for even further improvement of the reliability of the test.

(27) In the first working example, component 50 takes the form of a laminate. Component 50 has been formed by a fiber composite material having multiple laminate plies. The fiber composite material in the first working example is preferably a fiber-reinforced polymer material having a curable matrix and having reinforcing fibers. The matrix may especially be formed by an epoxy resin, and the reinforcing fibers may especially be carbon fibers or glass fibers.

(28) In the first working example, substrate 20 is repaired by bonding component 50 to it; substrate 20 is therefore already in cured form prior to production of the bond K and may already have been in use.

(29) Both substrate 20 and component 50 may be manufactured or have been manufactured using a preimpregnated semifinished fiber product (prepreg) or alternatively, for example, by the resin infusion method with a dry semifinished fiber product. Therefore, the component 50 to be bonded may have been formed from multiple layers of a prepreg, or may alternatively have been formed by plies of a dry semifinished fiber product that are impregnated by the resin infusion method. When the adhesive film 30 is laid onto the substrate 20 and the intermediate elements 70, it may especially have been frozen.

(30) An arrangement 110 according to a second working example is shown by FIG. 2. The differences in the second working example from the first working example are to be described hereinafter, with additional reference to the above remarks relating to the first working example.

(31) The arrangement 110 has a substrate 20, a component 50, two intermediate elements 70 and an adhesive film 130. By the adhesive film 130, a structural adhesive bond 40 from component 50 to the substrate 20 has been formed. The arrangement 110 also has two identical test sections 160. The test sections 160 have each been formed by a projection 135 of the adhesive film 130, with each of the projections 135 extending beyond an assigned part 52 of an edge 51 of component 50.

(32) Each of the projections 135 extends by its distal end, viewed from component 50, over regions of the intermediate element 70 and ends at the assigned intermediate element 70. Between the edge 51 and the assigned intermediate element 70, the projection 135 has in each case been bonded to the substrate 20 in a region 136 thereof. The test sections 160 each end in FIG. 2 at an end 169 on the intermediate element 70.

(33) The differences in the adhesive film 130 from the adhesive film 30 are elucidated hereinafter. The adhesive film 130 has a subarea 132 in the region of each of the projections 135. A structure of the adhesive film 130 comprises an internal support structure (not shown in the Figures) which forms part of a starting adhesive film 131 but also includes the adhesive. In addition, the structure of the adhesive film 130 has an additional reinforcing component 180 applied to the starting adhesive film 131 in the subarea 132. Alternatively, the reinforcing component 180 could have been introduced into the starting adhesive film 131.

(34) In the second working example, a mechanical strength of the structure comprising the additional reinforcing component 180 has been matched to a predefined target binding force of a bond K produced with the adhesive film 130 to form the adhesive bond 40 in such a way that—after completion of the bond K—when the adhesive film 130 is pulled away from substrate 20 with peeling stress on the bond K, the adhesive film 130 fails in a subregion 133 and preferably at the start thereof close to the edge 71 when the strength of the bond K attains or exceeds the target binding force. However, the adhesive film 130, and especially the support structure, does not fail in the subregion 133 when the strength of the bond K does not attain the target binding force, and there is instead peeling in the region 133. The subregion 133 of the adhesive film 130 is formed by that part of the subarea 132 in which the projection 135 has been bonded to the substrate 20; see FIG. 2. In the second working example, the mechanical strength of the structure of the adhesive film 130 in subarea 132 has thus been modified by addition of the reinforcing component 180 having predeterminable mechanical strength in order to achieve the desired matching to the target binding force. The reinforcing component 180 can be regarded as an additional carrier component, in which case the adhesive film 130 in subarea 132 has two carrier components: the internal carrier component of the starting adhesive film 131 and the additional reinforcing component 180.

(35) In the second working example, additional reinforcing component 180 has been formed by a textile fabric, especially a nonwoven fabric, a woven fabric or a knitted fabric. The internal support structure of the starting adhesive film 131 (not shown) has also preferably been formed by a textile fabric, especially a nonwoven fabric, a woven fabric or a knitted fabric.

(36) FIG. 2 also shows that, in the second working example, the additional reinforcing component 180 has thus been provided in a subarea 164 of the test section 160, as a result of which, in the manner described above, the mechanical strength of the test section 160 has been adjusted in subarea 164. In the second working example, the subarea 164 of the test section 160 ends between the intermediate element 70 assigned to the test section 160 and component 50 before reaching component 50 in an end 165.

(37) With the aid of the reinforcement of the bond structure by the additional reinforcing component 180, it is thus possible to accurately determine what force has to be withstood in the testing of the bond K by the test section 160 in a subregion 161 of the test section 160 that corresponds to the subarea 164 in order to demonstrate sufficient bond quality. In this case, given a good bond K, there is an intended break site or intended fracture site S in the reinforced subarea 164, at or close to the edge 71, and hence also before component 50. If the test section 160 tears off in the peeling removal only at or after the end 165 of the subarea 164 where the reinforcing component 180 is no longer present, or there is even progression of a tear into component 50, it is not possible to conclude that the bond is of adequate quality. The effect of the reinforcing component 180 is thus that, in the case of a poor bond K, the test section 160 breaks off only shortly before component 50 or a tear of the bond K is continued into component 50.

(38) In FIG. 2, subarea 164 of the test section 160 overlaps with sections of the assigned intermediate element 70, as a result of which subarea 164 extends across a section of an edge 71 of the intermediate element 70. The forces to be introduced to pull the test section 160 away, e.g. tensile forces, are thus introduced effectively into the reinforced subarea 164.

(39) In variants of the second working example, it would be possible to adjust the test section 160 in an appropriate manner with regard to its mechanical strength by addition of multiple additional reinforcing components 180.

(40) An arrangement 210 according to a third working example is shown in FIG. 3. The differences in the third working example from the first working example are to be described hereinafter, with additional reference to the above remarks relating to the first working example.

(41) The arrangement 210 has a substrate 20, a component 50, two intermediate elements 70 and an adhesive film 230. By the adhesive film 230, a structural adhesive bond 40 of component 50 to substrate 20 has been formed. The arrangement 210 also has two identical test sections 260. The test sections 260 have each been formed by a projection 235 of the adhesive film 230, with each of the projections 235 extending across part 52 of an edge 51 of component 50.

(42) Each of the projections 235 extends by its distal end, viewed from component 50, over regions of the intermediate element 70 and ends at the assigned intermediate element 70. Between the edge 51 and the assigned intermediate element 70, the projection 235 has been bonded to the substrate 20 in each case in a region 236 thereof. The test sections 260 in FIG. 3 each end at an end 269 on the intermediate element 70.

(43) In the third working example, the adhesive film 230 is of the same design as the adhesive film 30 in the first working example, and so reference may be made in this regard to the above remarks. However, the construction of the test section 260 differs from that of the test sections 60 and is described hereinafter.

(44) In FIG. 3, an additional material layer or ply 285 with elevated breaking strength has been disposed on the projection 235 in a subarea 266 of the test section 260 in each case. On curing of the adhesive film 230, the projection 235 also adheres to regions of the material layer 285. If the test section 260 is pulled away from the substrate 20 with peeling stress on the bond K, the bond K first breaks after the test section 260 has been lifted away from the intermediate element 70, as a result of which the fracture profile becomes visible and can be examined. In this way, it advantageously becomes possible, without damaging the structural adhesive bond 40, to examine the area between substrate 20 and adhesive film 230 and to check the mode of failure under which the bond K fails in the test and to verify whether this is permissible under the given conditions or not. Because the mechanical strength of the test section 260 is increased with the aid of the additional material layer 285 to such an extent that the test section 260 is not severed in subarea 266 even under the maximum force which is applied in the test, it is possible, in a subregion 268 of the test section 260 in which the projection 235 has been bonded to the substrate 20 and the additional material layer 285 is at the same time present, to produce a surface profile of the break area and examine it subsequently.

(45) In the third working example, the additional material layer 285 takes the form of a laminate ply with a fiber-reinforced polymer material. Advantageously, the additional material layer takes the same form as a ply of component 50 that comes into contact with the adhesive film 230. Thus, the additional material layer 285 also has a matrix and reinforcing fibers, the matrix having been formed from a curable polymer material and the reinforcing fibers present being, for example, carbon fibers or glass fibers. The additional material layer 285 can thus be referred to as a reinforced laminate strip.

(46) Analogously to the first working example, in the third working example as well, component 50 is preferably uncured or incompletely cured. In this case, the additional material layer 285 is likewise uncured or incompletely cured and, prior to production of the bond K, is preferably in the same state of curing as component 50. If, in one variant, component 50 has already cured, the additional material layer 285 in the third working example has also already cured.

(47) The subarea 266 ends with one end 267 thereof in FIG. 3 between the intermediate element 70 and component 50 before reaching component 50. Thus, between the end 267 and the edge 51, there remains a subregion 261 of the test section 260 in which, analogously to the above-described first working example, the adhesive attachment can be tested for the attainment of the target binding force. In this case, there is an intended tear site or intended fracture site S, in the presence of a sufficient binding force of the bond K, at or close to the edge 267 in the subregion 261. The third working example can thus test two criteria in order to assess the quality of the bond K, namely firstly the attainment of the target binding force and secondly the presence of a permissible mode of failure.

(48) In FIG. 3, subarea 266 overlaps with sections of the intermediate element 70 and extends here across a section of an edge 71 of the intermediate element 70. Thus, it is again ensured that the forces, when the test section 260 is pulled away, are introduced in such a way that the breaking of the bond K is reliably within the intended region 268 and the fracture profile can be examined.

(49) In addition, FIG. 3 shows, in a dotted line, a further intermediate element 275 which takes the form, for example, of a film, especially of a release film, and may be arranged in sections between the adhesive film 230 and the additional material layer 285. In the subregion 268, the additional material layer 285 in this variant too is bonded to the substrate 20 with mediation via the adhesive film 230. By lifting the additional material layer 285 at its distal end 286 from component 50, the breaking of the bond K in subregion 268, for testing purposes, can alternatively be initiated in an alternative manner proceeding from the bond of the additional material layer 285 to the projection 235 of the adhesive film 230 on the top side thereof. In another variant of the third working example, the further intermediate element 275 may be absent.

(50) An arrangement 310 in a fourth working example is illustrated in FIG. 4. The differences in the fourth working example from the third working example are to be described hereinafter, with additional reference to the above remarks relating to the previous working examples.

(51) The arrangement 310 has a substrate 20, a component 50, two intermediate elements 70 and an adhesive film 330. By the adhesive film 330, a structural adhesive bond 40 of component 50 to the substrate 20 has been formed. The arrangement 310 also has two identical test sections 360. The test sections 360 have each been formed by a projection 335 of the adhesive film 330, with each of the projections 335 extending beyond part 52 of an edge 51 of component 50.

(52) Each of the projections 335 extends by its distal end, viewed from component 50, over regions of the intermediate element 70 and ends at the assigned intermediate element 70. Between the edge 51 and the assigned intermediate element 70, the projection 335 is bonded to the substrate 20 in each case in a region 336 thereof. The test sections 360 each end in FIG. 4 at an end 369 on the intermediate element 70.

(53) The adhesive film 330 of FIG. 4 comprises a starting adhesive film 331. A structure of the adhesive film 330 comprises an internal support structure (again not shown in the Figures) of the starting adhesive film 331. The adhesive film 330 also includes an adhesive which is especially formed with an epoxy resin and is part of the starting adhesive film 331.

(54) In a subarea 332 of the adhesive film 330, in the region of one of the projections 335 in each case, an additional reinforcing component 380 has been applied to the starting adhesive film 331, where, in FIG. 4, the reinforcing components 380 are each in contact with the starting adhesive film 331 only in a subregion 333 that forms part of the subarea 332. The additional reinforcing component 380 has been formed by a textile fabric, especially a nonwoven fabric, a woven fabric or a knitted fabric. The internal support structure of the starting adhesive film 331 (not shown) has also preferably been formed by a textile fabric, especially a nonwoven fabric, woven fabric or knitted fabric.

(55) In the fourth working example, the additional reinforcing component 380 has thus been provided in a first subarea 364 of the test section 360. The first subarea 364 ends between the intermediate element 70 assigned to the test section 360 and component 50 before reaching component 50 in an end 365.

(56) On the projection 335 of FIG. 4, in addition, an additional material layer 385 having elevated breaking strength has been disposed in a second subarea 366 of the test section 360 in each case. On curing of the adhesive film 330, the projection 335 is also bonded to regions of the material layer 385, in a subregion 362 of the test section 360. The additional material layer 385 is of analogous design to the material layer 285 of the third working example, and so reference may be made to the above remarks, also with regard to the state of curing of material layer 385.

(57) The second subarea 366 ends with an end 367 between the intermediate element 70 and component 50. The first subarea 364 overlaps with the second subarea 366 of the test section 360 in an overlap region 368, extends across the end 367 of the second subarea 366 ends with the end 365 between the end 367 and component 50 before reaching component 50.

(58) In the fourth working example, a mechanical strength of a structure comprising the additional reinforcing component 380 and the internal support structure of the starting adhesive film 331 has been matched to a predefined target binding force of a bond K produced with the adhesive film 330 to form the adhesive bond 40 in such a way that—after completion of the bond K—when the adhesive film 330 is pulled away from the substrate 20 by peeling stress on the bond K of the adhesive film 330 in the subregion 333 between the ends 365 and 367 fails when the strength of the bond K attains or exceeds the target binding force, and does not fail in the subregion 333 when the strength of the bond K does not attain the target binding force. More particularly, the structure of the adhesive film 330 here can fail on attainment or exceedance of the target binding force in subregion 333. In other words, in the case of a bond K of good quality, the test section 360 breaks off at an intended break site S at the end 367 of the additional material layer 385 in the reinforced first subarea 364. If the quality of the bond K, by contrast, is insufficient, the test section 360 breaks off at the end or outside the subregion 333, for example shortly before component 50.

(59) Between the end 367 and the edge 51, there is thus a subregion 361 of the test section 360 that coincides spatially with subregion 333 and in which, analogously to the second working example described above, the adhesive attachment can be tested for attainment of the target binding force. In this case, the addition of the additional reinforcing component 380 can serve to modify the mechanical strength of the structure of the adhesive film 330 for adjustment of the mechanical strength of the test section 360 in subregion 361.

(60) When the test section 360 is pulled away from substrate 20 with peeling stress on the bond K, after the test section 360 is lifted away from the intermediate element 70, analogously to the third working example, the bond K between the edge 71 and the end 367 breaks in subregion 362, which again reveals the fracture profile.

(61) The second subarea 366 also overlaps with sections of the intermediate element 70 and extends here across a section of an edge 71 of the intermediate element 70. In the fourth working example too, it is thus ensured that the forces, for example tensile forces, when the test section 360 is pulled away, are initiated in such a way that the breaking of the bond K is reliably within the intended region 362 between the edge 71 and the end 367, and the fracture profile can be examined.

(62) The fourth working example thus also enables assessment of the quality of the bond K using the binding force and using the fracture profile, where the reinforcing component 380 offers a further improvement in matching to the target binding force.

(63) In addition, FIG. 4 shows, in a dotted line, a further intermediate element 375 which takes the form, for example, of a film, especially of a release film and may be arranged in sections between the adhesive film 330 and the additional material layer 385. In the region 362 facing component 50 between the edge 71 and the end 367, the additional material layer 385 in this variant too is bonded to the substrate 20 with mediation via the adhesive film 330. By lifting the additional material layer 385 at its distal end 386 from component 50, the breaking of the bond K, for testing purposes, analogously to the third working example, can be initiated in an alternative manner proceeding from the bond of the additional material layer 385 to the projection 335 of the adhesive film 330 on the top side thereof. In another variant, the further intermediate element 375 may be absent.

(64) FIG. 6 shows an arrangement 410 according to a fifth working example. The arrangement 410 differs from the arrangement 10 according to the first working example in that, in the fifth working example, the substrate 20 has not been provided with a recess for accommodation of component 450 by a material-removing processing operation, and also in that component 450 in FIG. 6 has been formed without tapering or chamfering at the edge face. FIG. 6 illustrates a planned adhesive bond 440 of component 450 to substrate 20. In addition, the arrangement 410 has the same design as the arrangement 10 of the first working example. It will be apparent that the working examples of FIGS. 2, 3 and 4 can also find use in variants analogously to the fifth working example in each case for a planned adhesive bond.

(65) FIG. 7 illustrates a schematic of an arrangement 510 according to a sixth working example, which is a variant of the third working example. The differences with respect to the third working example are to be described hereinafter. In addition, reference is made to the above remarks relating to the third working example.

(66) In FIG. 7, rather than the further intermediate element 275, a further intermediate element 575 is provided, which preferably again takes the form of a release film and from which the intermediate element 275 differs merely in that an edge 576 of the further intermediate element 575 facing component 50 has a greater distance from component 50 than the edge 71 of the intermediate element 70 that faces component 50.

(67) In a subregion 568 of the test section 560, as in subregion 268 in FIG. 3, the projection 235 has been bonded to the substrate 20, with simultaneous presence of the additional material layer 285, and it is again possible to produce and subsequently examine a surface profile of the break area. However, in the sixth working example, the projection 235, in a subregion 577 between the edge 71 and the edge 576 that adjoins subregion 568, is bonded to the additional material layer 285, but not to the substrate 20.

(68) In the sixth working example, it is also possible to examine the adhesive attachment between the adhesive film 230 and the additional material layer 285 placed on top, in order to obtain a conclusion as to the adhesive attachment between adhesive film 230 and component 50. For this purpose, the procedure in the sixth working example is as follows: first, the package of the adhesive film 230, the further intermediate element 575 and the additional material layer 285 becomes detached from the lower intermediate element 70 in FIG. 7 and peels off as described for FIG. 3. The test section 560 is designed such that, in the case of good adhesive attachment between the adhesive film 230 and the substrate 20, it then breaks off at the intended break site S at or close to the end 267 facing component 50, i.e. close to the end of the additional material layer 285 facing component 50.

(69) The broken-off part of the test section 560 now also includes at least the subregion 577 in which the adhesive film 230 has been bonded to the additional material layer 285. Now this “residual package” is disassembled at the upper release film 275. This involves peeling the adhesive film 230, the mechanical strength of which is matched to the adhesive attachment to be tested analogously to the manner described above, away from the additional material layer 285. Analogously to the intermediate element 70, the intermediate element 575 facilitates the detachment and gripping of the adhesive film 230 when it is peeled away from additional material layer 285. To make it easier, the broken-off part of the test section 560 can be turned around for this purpose.

(70) According to whether the test section 560 then breaks off or the bond between adhesive film 230 and the additional material layer 285 tears further, it is advantageously also possible to draw conclusions as to the adhesive attachment to the additional material layer 285. This is particularly advantageous when component 50, for instance a repair patch or a component part, and also the additional material layer 285 has been cured even before bonding to the substrate 20 and optionally provided with an appropriate surface pretreatment. In such a case, by the sixth working example, a useful control sample for the attachment between adhesive film 230 and component 50 and also for the effect of any pretreatment of component 50 can be created.

(71) FIG. 8 illustrates, in schematic form, an arrangement 610 according to the seventh working example, which is a variant of the fourth working example in which, analogously to the sixth working example, a further intermediate element 675 has been provided. Reference is made to the above elucidations relating to the fourth and sixth working examples and to the intermediate element 575. The seventh working example also enables the testing of the adhesive attachment between the additional material layer 385 and the adhesive film 330.

(72) In the seventh working example, a further reinforcing component 681 has been provided. With regard to design of the reinforcing component 681 and the effect thereof and the mechanical strength of the adhesive film 330 or of the test section 660, reference is made to the above remarks relating to the reinforcement components 180 and 380.

(73) The additional reinforcing component 681 in FIG. 8 is disposed between the lower intermediate element 70 in the Figure and the adhesive film 330 in a third subarea 664a of the test section 660, corresponding to a subarea 632 of the adhesive film 330. The reinforcing component 380 already described for FIG. 4 is disposed with its end 365 in the first subarea 364, with the first subarea 364 in FIG. 8 forming a subarea of the test section 660.

(74) The additional reinforcing component 681 ends at an end 665a of the third subarea 664a that faces component 50 between the edge 71 of the intermediate element facing 70 component 50 and the edge 676 of the further intermediate element 675 facing component 50. In a subregion 661a of the test section 660, corresponding to a subregion 633 of the adhesive film 330, between the end 665a and the edge 676, the adhesive film 330 has thus been reinforced by the additional reinforcing component 681 and additionally bonded by the additional material layer 385. In the subregion 661a, 633, the mechanical strength of the test section 660 is matched to the target binding force of the bond between the adhesive film 330 and the additional material layer 385. In a subregion 663 between the end 665a and the edge 71, the adhesive film 330, however, is not reinforced by the additional reinforcing component 681.

(75) Thus, in the seventh working example, the additional reinforcing component 681 does not affect the testing in the subregions 361 and 362. However, the seventh working example, after the test section 660 has been torn off and turned around as described above by pulling the adhesive film 330 with the reinforcing component 681 away from the additional material layer 385, can enable evidence of adhesive attachment in the direction of the additional material layer 385. The mechanical strength of the test section 660 in the subregion 661a, 633 has been adjusted such that, given good adhesive attachment between the adhesive film 330 and the additional material layer 385, the test section 660 breaks off in the subregion 661a, 633, preferably at an intended break site S′ at or close to the edge 676 of the further intermediate element 675, but does not break off in the subregion 661a, 633 when this adhesive attachment does not have the required binding force. The seventh working example can advantageously also find use in cases where component 50 and the additional material layer 385 are already cured.

(76) It will be apparent that the working examples of FIGS. 7 and 8 can each find advantageous use in variants analogous to the fifth working example for a planned adhesive bond, in which case, in FIGS. 7, 8, component 450 in FIG. 6 may be bonded to the substrate 20 rather than component 50.

(77) The test section 160, 260, 360 or 60 in the working examples of FIGS. 2, 3, 4, 6, 7 and 8 can in each case be pulled away analogously to the pulling-away in the first working example, for example using the roller device 91, as elucidated for FIG. 5.

(78) The substrate 20 in all the above-described working examples, prior to execution of the bond K, is in the form of an already cured fiber composite component. Alternatively, however, in variants of the production of a planned assembly group, the substrate 20 could still be in uncured or incompletely cured form, and further curing thereof could be effected, for example, during the curing of the adhesive film 30, 130, 230 or 330.

(79) In some variants of the above-described working examples, it may be preferable to subject the component 50 and the substrate 20, owing to their state of curing, to a preparation of the bonding surfaces, for example by surface grinding, pulling off a peel ply applied beforehand, sandblasting or plasma activation, especially when component 50 and substrate 20 have already been cured. In these variants, the pretreatment of the bonding surfaces is also undertaken in the same way for any additional material layer 285 or 385 present, especially one that has been cured, and also for the region in which the projection 35, 135, 235 or 335 is bonded to the substrate 20.

(80) In the case of a planned adhesive bond, as in FIG. 6 for instance, it may be the case that component 450 has already cured and the substrate 20 is partly as yet uncured or as yet incompletely cured. In the test as to whether adhesive attachment is sufficiently good, it is particularly advantageous when specifically adhesive attachment to already cured elements that may have been subjected to a surface pretreatment can be verified reliably. The use of an additional material layer 285 or 385, as described above for FIGS. 3, 4, 7 and 8, is particularly useful in such a case and is employable both in cases where there is tapering of component 50 and in cases of a planned bonded without tapering, as elucidated by way of example for FIG. 6.

(81) In addition, especially the first to fourth working examples described above can be used in the repair of fiber composite components of aerospace vehicles. If the surface of the substrate 20 which then takes the form, for example, of a fiber composite component of an aircraft for instance is processed prior to the bonding, for example, in a material-removing manner for removal of a lightning guard in the form of a copper mesh by grinding, the removal of material is preferably conducted in the same way on the substrate 20 where the projection 35, 135, 235 or 335 is bonded to the substrate 20. In this way, it is possible to prevent the bond K from being different in the region of component 50 and in the region of test sections 60, 160, 260, 360.

(82) Although the disclosure herein has been described in full above using preferred working examples, it is not limited thereto, but is modifiable in various ways.

(83) More particularly, the disclosure herein is useful in connection with adhesive bonds having one or more fiber composite components or elements, but is also applicable to adhesive bonds of other bonding partners.

(84) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE NUMERALS

(85) 10 arrangement

(86) 20 substrate

(87) 21 area

(88) 22 surface

(89) 30 adhesive film

(90) 35 projection

(91) 36 region (projection)

(92) 40 adhesive bond

(93) 50 component

(94) 51 edge (component)

(95) 52 part (edge)

(96) 60 test section

(97) 69 end (test section)

(98) 70 intermediate element

(99) 71 edge (intermediate element)

(100) 72 distance

(101) 90 roller device

(102) 91 roller body

(103) 110 arrangement

(104) 130 adhesive film

(105) 131 starting adhesive film

(106) 132 subarea (adhesive film)

(107) 133 subregion (adhesive film)

(108) 135 projection

(109) 136 region (projection)

(110) 160 test section

(111) 161 subregion (test section)

(112) 164 subarea (test section)

(113) 165 end (subarea)

(114) 169 end (test section)

(115) 180 reinforcing component

(116) 210 arrangement

(117) 230 adhesive film

(118) 235 projection

(119) 236 region (projection)

(120) 260 test section

(121) 261 subregion (test section)

(122) 266 subarea (test section)

(123) 267 end (subarea)

(124) 268 subregion (test section)

(125) 269 end (test section)

(126) 275 further intermediate element

(127) 285 additional material layer

(128) 286 end (additional material layer)

(129) 310 arrangement

(130) 330 adhesive film

(131) 331 starting adhesive film

(132) 332 subarea (adhesive film)

(133) 333 subregion (adhesive film)

(134) 335 projection

(135) 336 region (projection)

(136) 360 test section

(137) 361 subregion (test section)

(138) 362 subregion (test section)

(139) 364 first subarea (test section)

(140) 365 end (first subarea)

(141) 366 second subarea (test section)

(142) 367 end (second subarea)

(143) 368 overlap region

(144) 369 end (test section)

(145) 375 further intermediate element

(146) 380 reinforcing component

(147) 385 additional material layer

(148) 386 end (additional material layer)

(149) 410 arrangement

(150) 440 adhesive bond

(151) 450 component

(152) 510 arrangement

(153) 560 test section

(154) 568 subregion (test section)

(155) 575 further intermediate element

(156) 576 edge (further intermediate element)

(157) 577 subregion (test section)

(158) 610 arrangement

(159) 633 subregion (adhesive film)

(160) 660 test section

(161) 661a subregion (test section)

(162) 663 subregion (test section)

(163) 664a third subarea (test section)

(164) 665a end (third subarea)

(165) 675 further intermediate element

(166) 676 edge (further intermediate element)

(167) 681 further reinforcing component

(168) K bond

(169) PCS process control specimen

(170) R rotation

(171) S intended break or intended fracture site with good bond

(172) S′ further intended break or intended fracture site with good bond