Device for testing adhesive bonds and method of testing adhesive bonds and / or bonding properties of surfaces with the device

Abstract

The invention relates to a device for testing adhesive bonds, especially the fracture toughness of adhesive bonds, and to a method of testing adhesive bonds and / or bonding properties of surfaces with the device. It is therefore an object of the invention to eliminate the disadvantages of the prior art and to provide a device for testing adhesive bonds and a method of testing adhesive bonds and / or bonding properties of surfaces with the device. Said object is achieved by the features detailed in the claims.

Description

Device for testing adhesive bonds and method for testing adhesive bonds and / or bonding properties of surfaces with the device Description

[0001] The invention relates to a device for testing adhesive bonds, in particular the fracture toughness of adhesive bonds, and a method for testing adhesive bonds and / or bonding properties of surfaces using the device.

[0002] Bistability is the property of some systems that can assume two possible stable states, but can only change from one to the other through an internal or external influence. These systems are called bistable systems. It is important to note that these states can be assumed for the same parameter values. Some systems have more than two stable configurations. These systems are called multistable systems.

[0003] An example of a bistable system, specifically a bistable mechanical structure, is a light switch with a snap-action contact. As long as it is not touched, it remains in one position (on or off). When pressed, it either jumps back to the old position (not pressed hard enough) or to the new position (pressed hard enough for normal operation) after being released. Other examples from the field of technology include flip-flops in electronics and bistable springs in mechanics.

[0004] A mechanical bistable structure can be manufactured, for example, using simple laminates of fiber-reinforced plastics, such as carbon fiber-reinforced plastics. By applying a force / momentum against the bistable structure, it is possible to transform the structure from one stable configuration to another.

[0005] A bistable laminate is constructed from two or more layers bonded together. The layers consist of fibers in a plastic matrix. The layers can be arranged in various orientations, which gives the bistable laminate different properties, such as mechanical stiffness or the magnitude of the load required to change the stable state.

[0006] Bistable laminates are produced by arranging the layers asymmetrically. For the curing of heat-curing matrix materials or the processing of meltable matrix materials, the laminate is heated during processing and then cooled to room temperature. Since the fibers and the matrix material of the laminate have different thermal expansion coefficients, the thermal expansion of the layers due to the temperature change differs in the fiber direction and perpendicular to the fiber direction. If the layers are arranged asymmetrically, the induced thermal expansion results in a bistable laminate.

[0007] CN 1 01 422 973 A discloses a laminate of mixed composite material with a bistable structure.

[0008] JP 2005-161852 A discloses a composite material made of metal and fiber-reinforced plastic which is lightweight, has high strength and excellent durability and can therefore be used in various fields such as aircraft, automobiles, sports, civil engineering or construction, in particular for parts that bear stationary, dynamic or repeated bending stress.

[0009] DE 10 2004 055 130 A1 discloses a composite material with a layer structure and a component made therefrom.

[0010] DE 101 35 962 C1 discloses a method for producing a controlled deformable functional element and a functional element.

[0011] Adhesives are materials used to bond two or more components together by transferring loads between them. The overall bondability and / or fracture toughness of the bonded joint depends on, among other things, the adhesive properties, the adhesive composition, the surface properties of the components to be bonded, the condition of the component surface (cracks, dents, corrosion, etc.), contamination of both the adhesive and the component surface, the layer thickness of the bonded joint, and the introduction of impurities and / or voids into the bonded joint. Adhesive properties change over time due to aging, curing, and / or contamination of the adhesive. This can induce failure of the bonding process. Fracture toughness is the critical energy release rate of a structural situation in which crack growth or crack initiation occurs.If the energy release rate is less than the critical energy release rate (i.e. less than the fracture toughness), there is no crack or crack growth.

[0012] This loss of adhesiveness can occur with obvious contamination, such as oily contaminants, but also with hidden contamination, such as unwanted phosphorus contamination on surfaces in low concentrations. Such contamination can occur during transport, storage, handling, or even during cleaning of the substrates (surfaces).

[0013] Two failure mechanisms that can occur in an adhesive joint are cohesive and adhesive failure. Adhesive failure refers to failure at the interface between the adhesive and the substrate (adhesion of the adhesive to a surface), while cohesive failure refers to the failure of the adhesive itself. In adhesive failure, no adhesive residue is found on at least one of the surfaces of the parts to be joined. Cohesive failure occurs when a fracture leaves a layer of adhesive on both surfaces.

[0014] In addition to a quantitative value for the bond strength of an adhesive bond (tensile shear strength, fracture toughness, peel resistance), the fracture progression provides important information. Cohesive failure at strength values ​​typical for an adhesive can be considered an indication of a high-quality bond. Cohesive failure close to the substrate, typical for higher-strength bonds, can also be accepted, provided the adhesive layer remaining on the substrate is not too thin. Pure adhesive failure or failures with adhesive failure components can be attributed to errors in surface treatment or incorrect adhesive selection.

[0015] Adhesive bonds are increasingly used in industrial applications because they enable the construction of lightweight multi-material structures, for example, combining composites and metals. Compared to traditional joining methods such as welding, screwing, and riveting, adhesives are characterized by their ability to avoid local damage to the materials being joined, their ability to bond dissimilar materials, and their ability to avoid holes—which is particularly important when joining composite materials. With the increasing use of adhesives, it is important to accurately characterize them and predict their mechanical behavior and failure.

[0016] Destructive testing methods are used to assess the performance of adhesive bonds, even after ageing, which allow statements to be made about the strength, stiffness and deformability of an adhesive bond at the time of the test. The type and location of failure can also be determined.

[0017] A distinction is made between static (e.g., tensile shear test, roller peel test), cyclic (fatigue strength testing), and impact (testing under impact load). The most common method for measuring this is pulling the bond apart parallel to the bond line (tensile shear test) or at an angle to it (peel test, DCB test). The force required to pull the bond apart and the failure sequence provide information about the performance of the adhesive or the combination of adhesive and substrates in the application.

[0018] To precisely determine more specific values, such as the fracture toughness of an adhesive, various qualitative tests are known from the state of the art, which require specific equipment. A tensile testing machine is commonly used.

[0019] Representatively, DE102005057088A1 discloses a method and a device for testing the quality of an adhesive bond on a flat or plate-shaped component.

[0020] DE 10 2018 129 215 A1 discloses a method for the quantitative assessment of adhesive bonds.

[0021] Adhesives are quality products that can be manufactured reproducibly. Bonding defects that occur in industrial bonding are largely caused by application errors. This challenge is successfully addressed by adhesive technology quality assurance standards, such as DIN 2304 (Adhesive Technology - Quality Requirements for Bonding Processes) and ISO 21368 (Adhesives - Guidelines for the Fabrication of Adhesively Bonded Structures and Reporting Procedures Suitable for the Risk Evaluation of Such Structures).

[0022] DIN 2304 and ISO 21368 are aimed at general industry, while DIN 6701 and EN 17460 are explicitly aimed at rail vehicle construction. TL A-0023 refers to manufacturing and repair companies of military products that use adhesive bonding technology.

[0023] In all standards, the following three core elements are defined, compatible with each other: (i) classification of the bonds according to safety requirements, (ii) use of bonding personnel / bonding supervisors (KAP) and (iii) verification that over the entire life cycle of an adhesive bond, the stresses occurring are always smaller than its load capacity.

[0024] A disadvantage of the state of the art is that the common methods for testing the quality of an adhesive bond are time-consuming and require expensive machinery and appropriately trained operators. Furthermore, quantitative determination under laboratory conditions is rarely required, for example, for batch control after production, whereas in everyday use a qualitative determination of adhesive strength is sufficient. Furthermore, these methods do not provide direct information about whether an adhesive bond exhibits the fracture toughness appropriate for its intended use under specific operating conditions (e.g., temperature, pressure, humidity, etc.). Furthermore, in some cases it is not readily possible to provide the bonded part or sections of it for testing.

[0025] It is therefore desirable to have a test for checking an adhesive bond which can be carried out immediately at the time and place of intended use and which is also cost-effective and easy to handle. Description of the invention

[0026] It is an object of the invention to eliminate the disadvantages of the prior art and to provide a device for testing adhesive bonds and a method for testing adhesive bonds and / or bonding properties of surfaces with the device.

[0027] This object is achieved by the features listed in claims 1 and 11. Subclaims represent advantageous embodiments.

[0028] The object is achieved by a device for testing adhesive bonds, wherein the device for testing adhesive bonds comprises a bistable or multistable mechanical structure and a carrier. The bistable or multistable mechanical structure has at least one first and at least one second stable configuration. The carrier is provided for a material-to-material connection to a surface of the at least one first or at least one second stable configuration of the bistable or multistable mechanical structure. The material-to-material connection is the adhesive bond to be tested. A cross-section of the carrier determines a stress acting on the adhesive bond.

[0029] The device essentially consists of two bodies, the bistable or multistable mechanical structure as the first body and the carrier as the second body, which are intended to be connected, creating a gap filled by a certain adhesive. The carrier therefore represents a body intended to be joined to the bistable or multistable mechanical structure in order to test the adhesive bond used for the joining. For this purpose, the carrier can take on virtually any conceivable stable geometric shape. The carrier can also be designed to be at least partially flexible. It is also conceivable for the carrier to be designed as a bistable or multistable mechanical structure. It is conceivable that the bistable or multistable mechanical structure and / or the carrier designed as a bistable or multistable mechanical structure can also take on three or more stable configurations. It is also conceivable for the surfaces of both the bistable or multistable mechanical structure and the carrier to have a variety of geometries, as long as both bodies can be connected to one another along a gap.For example, the gap can extend along a flat, non-curved alignment of a curved bistable or multistable mechanical structure, such that the gap runs substantially parallel to an extension of vertices of the curved bistable or multistable mechanical structure. For this purpose, the surface of the bistable or multistable mechanical structure in the at least one first or the at least one second stable configuration can have a convex or concave curvature. However, the bistable or multistable mechanical structure and the carrier can also have two flat surfaces that can be connected to one another. The surfaces can also be uneven, for example, wavy or hilly. The adhesive-filled gap can have different layer thicknesses at different positions.It is also conceivable that the surfaces are at least partially interrupted along the extent of the gap, for example by notches, holes, gaps, or the like. The surfaces of the bistable or multistable mechanical structure and. The carrier can have different shapes so that they do not run parallel to each other.

[0030] According to various embodiments, the carrier is a joining part.

[0031] In order to test an adhesive bond on a material that corresponds to the material of a part to be joined, the carrier can be made of this same material.

[0032] According to various embodiments, the device for testing adhesive bonds further comprises a triggering mechanism which is designed to move the bistable or multistable mechanical structure from the at least one first stable configuration into the at least one second stable configuration and / or from the at least one second stable configuration into the at least one first stable configuration.

[0033] According to various embodiments, the trigger mechanism comprises an actuator on or within the bistable or multistable mechanical structure.

[0034] According to various embodiments, the device for testing adhesive bonds further comprises an offset mechanism which is designed to transfer a geometric change of the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure to a flat test surface of a joining part.

[0035] The offset mechanism allows the geometric changes of a flat bistable or multistable mechanical structure to be used in a sub-area (usually linear) to establish and test an adhesive bond with another flat substrate. the offset mechanism prevents the other planar substrate from preventing the planar bistable or multistable mechanical structure from transitioning from the at least one first to the at least one second, or from the at least one second to the at least one first, stable configuration.

[0036] According to various embodiments, the support has different cross-sections with different bending stiffnesses, e.g. a rectangular or H-shaped or T-shaped cross-section.

[0037] According to various embodiments, the bistable or multistable mechanical structure is a layered composite material. The layered composite material comprises at least two layers that are superimposed and firmly connected to one another.

[0038] According to various embodiments, the at least two layers are arranged asymmetrically.

[0039] According to various embodiments, the at least two layers comprise fiber-reinforced plastic.

[0040] According to various embodiments, the fiber-reinforced plastic is a carbon fiber-reinforced plastic.

[0041] The object is further achieved by a method for testing adhesive bonds using the device according to claim 1, comprising the following method steps: a. Closing a material-to-material connection of the carrier with the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure, b. Moving the bistable or multistable mechanical structure from the at least one first stable configuration into the at least one second stable configuration or from the at least one second stable configuration to the at least one first stable configuration, c. checking the integrity of the material connection of the carrier to the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure.

[0042] Closing the material-to-material connection of the carrier to the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure includes applying the adhesive to at least one surface of the carrier and / or the bistable or multistable mechanical structure, contacting (with or without contact pressure) the surfaces of the carrier and the bistable or multistable mechanical structure to be connected so that a gap filled with adhesive is created, and curing the adhesive.

[0043] The integrity of the bonded joint can be verified by visual inspection. In the most obvious case, the test results in two completely separated bodies. If one bonded joint is intact, the adhesive has passed the test and the fracture toughness of the adhesive is sufficient for the specific case under the specific conditions. In addition to visual inspection, other methods for verifying the integrity of the bonded joint are also conceivable. Numerous methods for this are known from the state of the art.

[0044] By moving the bistable or multistable mechanical structure from the at least one first stable configuration into the at least one second stable configuration, or from the at least one second stable configuration into at least one first stable configuration, the geometry of the gap filled with adhesive changes. Different stresses now occur locally in the adhesive layer. In general, tensile normal stresses (so-called peel stresses) occur locally and compressive normal stresses elsewhere. If the fracture toughness of the adhesive bond is too low, detachment or partial detachment will occur during the snap-in process (transition from one stable configuration to another). If, on the other hand, the fracture toughness of the adhesive bond is not exceeded during the test, no detachment will occur. The fracture toughness of the adhesive bond is described by the critical energy release rate of the adhesive in the adhesive bond. The energy release rate is changed by changing the geometry and / or the material of the bistable or multistable mechanical structure or the carrier.When conducting the test, the existing energy release rate is compared, from a physical perspective, with the fracture toughness of the bonded joint. The invention can be used to test whether the fracture toughness of an adhesive in an adhesive bond is acceptable or not by selecting a geometry of the substrate and / or the bistable or multistable mechanical structure that corresponds to a specific fracture toughness. If a more specific value for the fracture toughness of the adhesive is required, a qualitative test can be performed. By conducting several tests with different geometries, a range within which the fracture toughness of the adhesive lies can be established. It is also possible for an unbonded area, a so-called initial crack, to be included in the bonded joint from the outset, which can facilitate quantitative test evaluation.

[0045] The displacement from one stable configuration to another stable configuration is initiated by applying a force or momentum to the bistable or multistable mechanical structure. For simple on-site application, this can be done manually, e.g., by placing fingers on upper side edges or corners of the bistable or multistable mechanical structure and then applying a rotation with the hands. Since the bistable or multistable mechanical structure is at least bistable, when the unstable state is initiated, it will transition to another stable state. Therefore, the exact magnitude of the action required for the state change does not need to be known, and the hands can be used. Another example of inducing the displacement would be a 3-point bend, which could be performed in a tensile testing machine.A state change could also be triggered by actuators mounted on or within the bistable or multistable mechanical structure.

[0046] The device according to the invention for testing adhesive bonds makes it easy, quick, and inexpensive to test whether the adhesive properties of a specific adhesive are still acceptable at the time and place of intended use. This can generally be used for industries where adhesives are used, but also in private households. Examples are the wind energy industry, the construction industry, and shipbuilding / marine technology, where the invention makes it possible to test the adhesive properties on site / in the field. In general, companies there use adhesives for installations or repairs. Smaller companies there use adhesives and do not have access to the testing machines used today or do not have the necessary knowledge to Conducting such tests. Another case is the recurring testing of adhesive properties in production lines in mechanical engineering or electronics. In these cases, supplied components must be subjected to an incoming goods inspection for adhesive properties. This can be done with the device according to the invention for testing Adhesive bonding can be performed much more easily without the need for extensive personnel training. This can also be used during the production line to repeatedly check whether the curing parameters of adhesives are correct or whether any adhesive deterioration has occurred. Implementation of the invention

[0047] The invention will be explained in more detail with reference to several exemplary embodiments. Figure 1A Carrier on bistable or multistable mechanical structure; first stable configuration, Figure 1 B Carrier on bistable or multistable mechanical structure; second stable configuration, Figure 2 Carrier on bistable or multistable mechanical structure in XZ plane, Figure 3A Beam on bistable or multistable mechanical structure in YZ plane without initial crack, Figure 3B Beam on bistable or multistable mechanical structure in YZ plane with initial crack, Figure 4A Carrier on bistable or multistable mechanical structure without delamination in YZ plane, Figure 4B Carrier on bistable or multistable mechanical structure with detachment in YZ plane, Figure 5 exemplary beam cross-sections, Figure 6 bistable or multistable mechanical structure bonded to a joining part surface, Figure 7 Offset mechanism.

[0048] In the description, reference is made to the accompanying drawings, in which, by way of illustration, specific embodiments are shown in which the arrangement according to the invention may be practiced. In this regard, directional terminology such as "top," "bottom," etc., is used with reference to the orientation of the described drawings. The directional terminology is for illustrative purposes and is in no way limiting.

[0049] It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It is understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0050] In the figures, identical or similar elements are provided with identical reference numerals where appropriate.

[0051] The device according to the invention for testing adhesive bonds is shown in Figure 1. The device for testing adhesive bonds comprises a bistable or multistable mechanical structure 1 and a carrier 2. The bistable or multistable mechanical structure 1 has at least one first and at least one second stable configuration. The carrier 2 is designed for integral connection to a surface of the at least one first or the at least one second stable The configuration of the bistable or multistable mechanical structure 1 is provided. The bonded joint is the adhesive joint to be tested. A cross-section of the beam 2 determines the stress acting on the adhesive joint.

[0052] The bistable or multistable mechanical structure 1 according to Figure 1 is an advantageous flat structure, but can also take any other shape, depending on the adhesive bond or surface to be tested. The bistable or multistable mechanical structure 1 can be a layered composite material having at least two layers that are superimposed and firmly connected to one another. The at least two layers can be arranged asymmetrically. The at least two layers can comprise fiber-reinforced plastic, which can be carbon fiber-reinforced plastic. The carrier 2 according to Figure 1 is a cuboid body that is integrally connected to the bistable or multistable mechanical structure 1 along a flat, non-curved direction (Y-axis) by means of an adhesive 3, as shown in Figure 2.As shown in Figure 3, the bonding of the carrier 2 can be carried out with or without an initial crack. The carrier 2 can also take on a different shape. For example, the carrier 2 can have an H-shaped or T-shaped cross-section in addition to a rectangular one. Example cross-sectional designs of the carrier 2 are shown in Figure 5. By changing the configuration of the carrier 2, the stress acting on the adhesive bond (characterized by the energy release rate) is changed. The configuration therefore determines the stress level. If the stress is below the critical energy release rate (i.e. the fracture toughness), no crack formation occurs. An adhesive bond can then, under the. prevailing conditions, with the result "OK." For any quantitative statements, the configuration of support 2 can then be changed so that a higher stress (energy release rate) is present, at which the test is repeated.

[0053] By displacing the surface of the bistable or multistable mechanical structure 1 from the at least one first stable configuration (a concave curvature according to Figure 1A) to the at least one second stable configuration (a convex curvature according to Figure 1B), the geometry of the gap filled with adhesive changes abruptly, since the curvature of the bistable or multistable mechanical structure 1 runs along the adhesive bond in the at least one first stable configuration and transversely to the adhesive bond in the at least one second stable configuration. If the fracture toughness of the adhesive 3 is insufficient, the carrier 2 tears away from the bistable or multistable mechanical structure 1 at a detachment location 4, as shown in Figure 4A.If the fracture toughness of the adhesive 3 is sufficient, the carrier 2 remains crack-free and firmly bonded to the surface of the bistable or multistable mechanical structure 1, as shown in Figure 4B. Since this method tests the adhesive 3 in relation to the carrier 2 and the bistable or multistable mechanical structure 1, cohesive failure is generally of interest. In the case of cohesive failure, the fracture must occur within the adhesive 3, i.e., some adhesive 3 must remain on both the carrier 2 and the bistable or multistable mechanical structure 1. Therefore, good surface adhesive properties for the carrier 2 and the bistable or multistable mechanical structure 1 are required.

[0054] The device for testing adhesive bonds can have a triggering mechanism to move the bistable or multistable mechanical structure 1 from the at least one first stable configuration to the at least one second stable configuration and / or from the at least one second stable configuration to the at least one first stable configuration. For this purpose, the triggering mechanism can have an actuator on or within the bistable or multistable mechanical structure. For example, the actuator can be a pressure point to which a force is exerted. Other ways of triggering the displacement between the configurations are conceivable. For example, this can be done magnetically or thermally.

[0055] As shown in Figure 6, the device for testing adhesive bonds can also be applied directly to adherends. In this case, one adherend to be tested corresponds to the carrier 2. In this arrangement, testing can be carried out for both cohesive failure and adhesive failure of the interface between the adherend to be tested and the adhesive 3. In the latter case, adhesive 3 must still be present on the bistable or multistable mechanical structure 1 after crack propagation. The bistable or multistable mechanical structure 1 is bonded directly to a test surface of the adherend 5, in this case an edge. If the failure lies within the adhesive 3, cohesive failure is observed. If this is not the case, this test identifies adhesive adhesive failure.In industrial practice, the adhesive failure of the adhesive clearly indicates that there is surface contamination and / or the wrong adhesive was chosen.

[0056] As shown in Figure 7, the device for testing adhesive bonds can further comprise an offset mechanism 6, which is designed to transfer a geometric change of the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure 1 to a flat test surface of a joining part 5 in order to establish and test an adhesive bond with another flat substrate. The offset mechanism enables the bistable or multistable mechanical structure 1 to be placed on a flat test surface of a joining part 5, see Figure 7. Without the offset mechanism 6, the bistable or multistable mechanical structure 1 could not reach a final position of the at least one second stable configuration, since it would first touch the flat test surface of the joining part 5 and thus be hindered from further geometric changes. A method for testing adhesive bonds using the device according to claim 1 is shown in Figure 1. The method comprises (a) closing a material-to-material connection of the carrier 2 to the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure 1, (b) curing the adhesive 3, (c) moving the bistable or multistable mechanical structure 1 from the at least one first stable configuration to the at least one second stable configuration or from the at least one second stable configuration to the at least one first stable configuration and (d) checking an integrity of the material-to-material connection of the carrier 2 to the surface of the at least one first or the at least one second stable configuration of the bistable or multistable mechanical structure 1. Reference symbol 1 bistable or multistable mechanical structure 2 carriers 3 Adhesive 4 Transfer location 5 Test surface of the joining part 6 Offset mechanism

Claims

Claims 1. A device for testing adhesive bonds, comprising a bistable or multistable mechanical structure (1) and a carrier (2), wherein the bistable or multistable mechanical structure (1) has at least two stable configurations, wherein the carrier (2) is provided for materially bonding to a surface of the first or second stable configuration of the bistable or multistable mechanical structure (1) along a gap, wherein the materially bonded connection is the adhesive bond to be tested, and wherein a cross-section of the carrier (2) determines a stress acting on the adhesive bond.

2. Device for testing adhesive bonds according to claim 1, characterized in that the carrier is a joining part.

3. Device for testing adhesive bonds according to claim 1 or 2, further comprising a trigger mechanism which is designed to move the bistable or multistable mechanical structure (1) from the first stable configuration to the second stable configuration and / or from the second stable configuration to the first stable configuration.

4. Device for testing adhesive bonds according to claim 3, characterized in that the triggering mechanism comprises an actuator on or within the bistable or multistable mechanical structure (1).

5. Device for testing adhesive bonds according to one of the preceding claims, further comprising an offset mechanism (6) which is designed to transfer a geometric change of the surface of the first or second stable configuration of the bistable or multistable mechanical structure (1) to a flat test surface of a joining part (5).

6. Device for testing adhesive bonds according to one of the preceding claims, characterized in that the carrier (2) has different cross-sections with different flexural rigidities.

7. Device for testing adhesive bonds according to one of the preceding claims, characterized in that the bistable or multistable mechanical structure (1) is a layered composite material, wherein the layered composite material has at least two layers which are superimposed and firmly connected to one another.

8. Device for testing adhesive bonds according to claim 7, characterized in that the at least two layers are arranged asymmetrically and / or antisymmetrically.

9. Device for testing adhesive bonds according to claim 7 or 8, characterized in that the at least two layers comprise fiber-reinforced plastic.

10. Device for testing adhesive bonds according to claim 9, characterized in that the fiber-reinforced plastic is a carbon fiber-reinforced plastic.

11. A method for testing adhesive bonds using the device according to claim 1, comprising the following method steps: a. Closing a material connection of the carrier (2) with the surface of the first or second stable configuration of the bistable or multistable mechanical structure (1) along a gap, b. Moving the bistable or multistable mechanical Structure (1) from the first stable configuration to the second stable configuration or from the second stable configuration to the first stable configuration, c. Checking the integrity of the material connection of the support (2) to the surface of the first or second stable configuration of the bistable or multistable mechanical structure (1).

Images