Test device for the mechanical testing of a beam-shaped test specimen

Abstract

The invention relates to a test device for the mechanical testing of a beam-shaped test specimen (1), in particular a rotor blade, comprising a clamping device (2) anchored in a clamping field (3) for clamping the beam-shaped test specimen at a clamping point (1') of the beam-shaped test specimen, one or more coupling elements (4A, 4F) connected to the beam-shaped test specimen, in particular load frames, one or more active load introduction means (5A, 5B) each connected to a coupling element, and one or more passive load introduction means each connected to a coupling element, at least one of which has a spring device connected to the clamping field, wherein the spring device has a spring module (14) with several, in particular similar, mechanically parallel connected spring elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J).The use of a spring module makes the test device flexibly adaptable to the individual test situation.

Description

[0001] The invention relates to a testing device for testing beam-shaped test specimens, for example rotor blades.

[0002] Beam-shaped components, such as towers or rotor blades of wind turbines, are subjected to heavy loads and significant wear during operation. Rotor blades, which are often over 30 meters long and sometimes much longer, must therefore be tested under extreme conditions and across a wide range of alternating loads for safety reasons.

[0003] Fatigue tests are essential for determining the performance of rotor blades, or more generally, beam-shaped test specimens subjected to high loads during operation. These tests aim to simulate as realistic a load as possible on a test specimen, such as a rotor blade, using test rigs / devices. This involves loads that typically occur during the operation of a rotor blade in a wind turbine. Due to the aforementioned dimensions of rotor blades, testing is associated with considerable technical, time, and financial resources.

[0004] One way to simulate realistic load conditions in testing procedures for wind turbines is to test individual components, such as towers, rotor blades, or sections of such components. Several of these components are measured separately in test rigs. This allows conclusions to be drawn about the performance of the entire wind turbine.

[0005] Dynamic structural testing in the resonance range of elongated and slender test specimens, such as entire rotor blades or rotor blade segments of wind turbines, presents a challenge with increasing lengths. The longer a test specimen is, the lower its natural frequency, and the longer the test duration for a given number of load cycles. With the test duration, which can range from days to months for a single load test, not only do costs increase, but the waiting time for the approval of new types also lengthens.

[0006] The challenge of long testing times due to low natural frequencies of a component can be countered, for example, by attaching elastic elements to suitable locations on the test specimen, thereby increasing the system natural frequency for uniaxial or biaxial excitation in bending load directions of the system consisting of the test specimen and the elastic element.

[0007] Such a solution typically incurs high costs, as an individual elastic element with a specific stiffness and deflection must be designed and manufactured for each test campaign, for example for a rotor blade type.

[0008] As technology advances, rotor blade types are becoming increasingly longer, requiring elastic elements with greater stiffness and increasing deflection for load testing. One problem is that the deflection of an increasingly longer test specimen, for example at the tip, becomes so large that conventional devices using an elastic element result in large displacements / deflections, such as those of a spring, and thus large spring lengths (approx. 20 m) and large oscillating masses, such as a lever arm structure, which counteract the spring effect. To enable such large deflections while maintaining high stiffness, the elastic elements become very large, heavy, and expensive.

[0009] German patent application DE 10 2018 218 515 A1 discloses a test device for rotor blades of wind turbines, in which both active load introduction means for periodic deformation of a blade and passive load introduction means in the form of springs for shaping system natural frequencies and bending load distributions are provided.

[0010] US patent US 3 062 526 A discloses an embodiment of a leaf spring that is installed in a vehicle.

[0011] German patent application DE 102 42 236 A1 discloses a seat suspension for a vehicle seat in which the spring characteristics of spring packages can be adjusted by means of movable connecting elements.

[0012] The present invention is based on the objective of creating a testing device for the mechanical testing of beam-shaped test specimens that enables the most flexible use possible with short testing times and low effort.

[0013] The problem is solved by a testing device with the features of the invention according to claim 1. The dependent claims present possible implementations of such a testing device.

[0014] Accordingly, the invention relates to a test device for the mechanical testing of a beam-shaped test object, also called a test specimen, in particular a rotor blade, comprising a clamping device anchored in a clamping field for clamping the beam-shaped test object at a clamping point of the beam-shaped test object, one or more coupling elements connected to the beam-shaped test specimen, in particular load frames, one or more active load introduction devices, each connected to a coupling element, as well as one or more passive load introduction means connected to a coupling element, at least one of which has a spring device connected to the clamping field, wherein the spring device comprises a spring module with several, in particular identical, spring elements mechanically connected in parallel to each other.

[0015] To perform a test, the beam-shaped specimen is clamped at the clamping point and mechanically deflected at one or more points in one or more directions using active load application devices. These active load application devices can include hydraulic or pneumatic pistons or electric linear or rotary drives that generate a deflection which is transmitted directly or via transmissions, such as linkages or lever mechanisms, to the specimen. This allows for extensive control of the deflection path, deflection rate, force, and frequency. In addition, at least one passive load application device with a spring module is provided, which can act on the specimen at a suitable point to achieve a desired distribution of the bending load and to adjust the system's natural frequency as desired.Due to the often large dimensions of the test specimens, especially when they are components of wind turbines, such as rotor blades, the spring module and its individual spring elements must also be of a certain size to achieve the necessary forces and spring deflections. Therefore, the spring modules and spring elements are frequently longer than 2 meters, often longer than 3 meters, 5 meters, or even 15 meters. The coupling elements for attaching the load application devices to the test specimen can be designed as load frames, but also in any other conceivable way, for example, as pads or other fasteners that can be attached to the test specimen by adhesive or other means, and to which rods, levers, or cables can be connected via eyelets, joints, or other fasteners.

[0016] Because the spring assembly is designed as a spring module with multiple spring elements, the number of parallel spring elements and their individual configurations can be flexibly selected, allowing for flexible customization of the overall spring module properties. For example, individual spring elements can have the same or different stiffnesses to adjust the overall stiffness of the spring assembly. This eliminates the need to build a separate, customized spring assembly for each test specimen, and elements of the spring assembly can be reused. Furthermore, the spring assembly can be adapted during testing to the specific test conditions and the characteristics of the test specimen. Currently, spring elements are often provided based on theoretical model calculations, which then do not correspond to the actual test specimen with sufficient accuracy.In such a case, the spring module can be reassembled, or a spring element can be removed or added. A spring module can, in principle, combine different spring shapes, although in many cases combining similar spring elements is advantageous.

[0017] The example of spring elements in the form of leaf springs will be discussed in more detail below.

[0018] In a specific embodiment of the test device, it is provided that the spring module has spring elements in the form of one or more flexible beam elements arranged parallel to each other, in particular in the form of leaf springs.

[0019] Such flexible beam elements, which can be, for example, leaf springs, but also flexible tubes or sandwich bodies or hollow bodies composed of several different materials, can be easily combined by arranging them side by side, or in some cases alternatively or additionally, one above the other. With suitable design, they allow for large spring deflections and offer considerable design flexibility with regard to the achievable stiffness. Fittings, such as clamping devices, can be provided at the fixing points to transmit the force; these will be explained in more detail below.

[0020] Furthermore, it is provided that one or more clamping devices are provided on the spring module, each having two clamping beams that can be connected or are connected by connecting elements, between which the flexible beam elements, in particular in the form of leaf springs, can be clamped.

[0021] The clamping beams can be straight or curved, and the connecting elements can be screws or threaded studs in conjunction with threads in the clamping device or with nuts. The clamping beams can also have an elastic compensating layer on their side facing the spring elements, which compensates for any slight differences in the thickness of different spring elements during clamping and also prevents loosening of the clamp during the test procedure.

[0022] Furthermore, it may be provided that the spring module is connected to the clamping field at at least one of its ends by means of a joint or a hinge joint.

[0023] To exert a spring force on the test specimen, a spring assembly is typically connected to the clamping frame, which also houses the clamping device for the specimen. The clamping frame includes foundations and rigidly connected fixtures for supporting elements of the test fixture and for transmitting the force. A spring module can be rigidly connected to the clamping frame. However, to accommodate potential deformations of the spring module under load and to achieve the simplest possible spring characteristics, certain degrees of freedom can often be allowed at the spring module's mounting points. A hinged connection between the spring module and the clamping frame can serve this purpose.

[0024] Another possible implementation involves connecting the spring module at one of its ends to a joint or hinge joint by means of a shackle, which is connected to the clamping field.

[0025] Such a connection of a spring module to a joint allows, in addition to the possibility of bending the spring module, also a shortening or lengthening of the spring, or more precisely, a change in the distance between the two ends of the spring module. The shackle can be designed as a rod that is pivotably attached by means of eyelets to both the joint connected to the clamping field and to the spring module.

[0026] Furthermore, the spring module may be provided with one or more releasable clamping devices in which one or more flexible beam elements can be clamped.

[0027] A clamping device allows identical beam-shaped spring elements, arranged side by side or one above the other, to be easily clamped together. The clamping device then serves to mechanically connect a point on the spring module to another element of the test fixture, such as a rod, lever, or rope, or to the clamping frame. Through the clamping device, tensile or compressive forces can thus be introduced into or out of a spring module and transferred to the test specimen.

[0028] It may also be provided that at least one clamping device is movable along the spring module and is designed to clamp the flexible beam elements or leaf springs of the spring module selectively at one of several positions.

[0029] Because one or more clamping devices are movable along the spring module, the spring forces and spring travel can be adjusted quickly and easily. For this purpose, the clamping devices can first be released, then moved, and finally clamped again at a different point on the spring module. During the load test itself, the clamping devices are not movable.

[0030] Another possible implementation involves connecting at least one clamping device to the clamping field by means of a joint or a hinge joint and / or connecting at least one clamping device to a joint or hinge joint connected to the clamping field by means of a shackle.

[0031] It may also be provided that at least one clamping device is connected to the test specimen by means of a transmission element, in particular by means of a lever.

[0032] Various flexibly interchangeable intermediate and additional elements, for example in the form of flexibly stackable sheet metal packages, can be provided to adapt the desired length and lever ratios as well as the storage location of the lever and also to align and position the elements of the test device in a suitable way in all spatial directions relative to the test specimen.

[0033] Another possible implementation involves connecting the spring module to the clamping field at only one or at least two points along the longitudinal direction of the flexible beam elements or leaf springs.

[0034] It may also be provided that a clamping device connected to the test specimen lies between two clamping devices connected to the clamping field when viewed in the longitudinal direction of the flexible beam elements of a spring module, or that a spring module is only clamped firmly to the clamping field on one side and a clamping device connected to the test specimen clamps the spring module at one point along the longitudinal direction of the flexible beam elements of the spring module.

[0035] If the spring module is connected to the clamping field at only one point, then, in the case of a module with beam-shaped spring elements, it is rigidly and angularly stiffly connected to the clamping field at one clamping point. In this case, a point of the spring module spaced away from the clamping point is connected to the test specimen, for example, by means of a clamping device.

[0036] This variant allows for long spring travels with relatively low spring forces. If the spring module is connected to the clamping field at least at two points along the longitudinal direction of the beam elements or leaf springs, it can be connected to the test specimen at a third point between these two points, for example, by means of a clamping device and a lever. In this case, the achievable spring travel is less than with only a single-sided attachment of the spring module, but the achievable spring forces are greater.

[0037] Another possible implementation option is to connect the spring module to the test specimen, in particular to a rotor blade, or to a lever arrangement connected to the rotor blade, at only one or at least two points along the longitudinal direction of the beam elements.

[0038] By coupling the spring module to the test specimen in this way, for example by means of a crossbeam, a 4-point bending load on the spring module is achieved. This type of coupling allows the generation of very large spring forces.

[0039] Another possible implementation involves arranging several beam elements parallel to each other in a spring module, and ensuring that at several points or at all points along the longitudinal direction of the beam elements, several or all beam elements have the same thickness in the direction of the mechanical load for which the spring module is intended, such that they can be clamped together by a clamping device.

[0040] The beam elements can have different widths, for example, while having the same thickness, in order to achieve the desired stiffness.

[0041] Therefore, it can also be provided that several beam elements of different stiffness, in particular several leaf spring elements of different widths, are arranged parallel to each other in a spring module.

[0042] The individual spring elements can have a constant or varying cross-section or cross-sectional shape along the length of the spring module. This also influences the stiffness of the individual spring elements and thus the stiffness of the spring module.

[0043] In a clamping device, several spring elements can also be arranged parallel to each other with a free distance between them in order to achieve a greater stiffness of the spring module in a direction transverse to the planned load direction compared to an arrangement with spring elements arranged directly next to each other and without distance between them.

[0044] The individual spring elements can be designed as solid bodies or as hollow bodies. When designed as hollow bodies, the moving mass is significantly reduced, while the cross-sectional design allows for stiffness comparable to that of solid bodies. Instead of hollow bodies, lightweight but stable cores with a casing made of a tensile-strength and flexurally rigid material, such as fiber-reinforced plastics, can also be used.

[0045] By appropriately designing the clamping devices, several spring elements can be arranged one above the other in the direction of the load, either in addition to or instead of the parallel arrangement of spring elements in a module. For this purpose, more than two clamping beams can also be provided in a single clamping device.

[0046] The invention is shown below with reference to exemplary embodiments in figures of a drawing and then described.

[0047] This shows: Fig. 1: Schematic overview of a test device for rotor blades of wind turbines, Fig. 2, Fig. 3: Parts of a test device, wherein a spring module is arranged in different positions relative to the rotor blade to be tested, Fig. 4: a test device in a perspective view, Fig. 5: the device from the Fig. 4 in a side view, Fig. 6, Fig. 7: Views of a spring module with coupling elements seen in the longitudinal direction of the spring elements, Fig. 8, Fig. 9: Side views of a spring module and a lever mechanism with different lever ratio configurations, Fig. 10, Fig. 11, Fig. 12: various implementations of a 2-point coupling of a spring module to a lever, Fig. 13: a side view of a spring module with a lever mechanism, wherein the lever is coupled to a free end of the spring module, Fig. 14: a lever of a lever mechanism, the mass of which is reduced by a telescopic design, Fig. 15: the arrangement from the Fig. 14 in a front view, Fig. 16, Fig. 17: Longitudinal sections of spring elements, Fig. 18: a side view of a spring element, Fig. 19: another longitudinal section of a spring element, Fig. 20, Fig. 21: Top views of various spring elements, Fig. 22: a perspective view of a spring element, Fig. 23, Fig. 24 to Fig. 25: Cross-sections of different spring modules, Fig. 26, Fig. 27, Fig. 28, Fig. 29, Fig. 30 to Fig. 31: Cross-sectional views of various spring elements, as well as Fig. 32, Fig. 33: various other embodiments of clamping devices.

[0048] To make the test device easily customizable and adaptable, spring elements of uniform length, such as leaf springs, but of varying, graduated widths can be connected side-by-side in a spring module, depending on the required stiffness. Adjacent spring elements can have the same thickness, at least in sections along their length, to allow for easy clamping together using clamping bars. In the Fig. Figure 1 schematically depicts a spring module 14 with leaf springs in a side view. The maximum deflection is limited by the permissible elongation of the spring elements. For this purpose, the beam-shaped spring elements are fixed at their ends, as well as in the middle or at another point between the ends, using clamping devices, also called clamps. The clamps at both ends are connected to the clamping frame by means of joints or hinge joints 10A and 10E, with one end being mounted to the clamping frame by means of an additional hinge 10B and a shackle 13 in the form of a rod pivotally connected at both ends, thus allowing movement / elongation of the spring module in the longitudinal direction of the leaf springs while simultaneously permitting vertical deflection of the spring elements.The length of the shackle is adjusted so that the line of action 8B' of the load vector at the central clamp / clamping device is almost parallel to a target line of action 8A' of the force acting on the rotor blade in a longitudinal plane of the rotor blade / test specimen 1. To transmit the spring force to the test specimen 1, the force at the central clamp is transferred via a rod 8B, mounted via hinges 11A and 11B, to a lever arm 9A, which in turn is connected to the test specimen 1 by means of a rod 8A, for example, with ball joints 11P and 11Q. The desired (maximum permissible) deflection in the center of the spring assembly / spring module 14 can be adjusted via the lever arm ratio, depending on the desired deflection of the test specimen during the test and / or the spring stiffness.The lever arm is connected to the test specimen 1 via a coupling element in the form of a frame / load frame 4F, which surrounds and clamps the test specimen and is at least partially adapted to its shape. When the test specimen / rotor blade rotates about its longitudinal axis, the load frame 4F rotates with it, and the rod 8A can be tilted for adjustment. The position of the joint 11P on the load frame then adjusts to the position of the load frame relative to the rod 8A. To achieve the most comprehensive possible mass reduction in the moving parts of the test device, the spring elements, or at least some of the spring elements, can be designed based on lightweight construction principles. This includes the use of materials with low density and a high modulus of elasticity in the longitudinal direction of the spring elements, such as fiber-reinforced composites.Furthermore, a sandwich composite construction can be used for the spring elements, in which a low-density core material is covered on two opposite sides or on all sides with outer layers of a material with a high modulus of elasticity, which may also have a higher density. In this case, the core must have sufficient shear stiffness.

[0049] The individual spring elements each have a cross-section that allows for common clamping. For this purpose, their heights at the clamping points or in the longitudinal sections intended for clamping are nearly identical. Besides rectangular cross-sections, other cross-sectional shapes are conceivable, as long as clamping is possible in a common clamp / clamping device. Possible cross-sections for the spring elements include various trapezoids tilted or inverted about their flat axis, extruded I-profiles, as well as wound box or circular cross-sections. Examples of these are shown in the Fig. Figures 16-31 illustrate this. It is advantageous that these various spring elements, when combined in a spring module, have a uniform permissible elongation. The cross-section can be constant or vary along the length. Increasing the cross-section of a spring element, particularly increasing its vertical extension, in the middle of the spring module results in high stiffness where deflection is typically greatest. Increasing the cross-section towards the center of a spring element by increasing its width is also conceivable. In a sandwich construction, the core or the face sheets can vary in height along the length of the spring element. The lever arm 9A of a lever coupled to a spring module 14 can be designed as a double-T beam to achieve high stiffness with minimal weight.Other cross-sectional shapes of the spring elements are also possible, such as a trapezoidal shape or a tube cross-section, in order to favorably absorb shear forces and a bending moment.

[0050] To make rods (connecting rods) lighter, materials such as CFRP (carbon fiber reinforced plastic) or aluminum can be used. High stiffness is essential in these cases. When using CFRP tubes or profiles, clamps are required for support. Coupling to the test specimen / load transfer into the test specimen is then possible, for example, using clamps or an adhesive bond.

[0051] The support points or coupling points of the spring module 14 or the spring elements can be made movable by using a clamping device to provide a further possibility for adjusting the deflection and stiffness of the spring module. Likewise, the bearing point of the lever arm 9A on the support block can be made adjustable, for example by providing insertable sheet metal stacks.

[0052] Fig. Figure 1 shows a side view of a test setup (here shown using the example of a biaxial test setup; uniaxial test setups in the pivot and impact directions with other excitations, for example by means of mass oscillators, are also possible). This illustration is intended to show that the test specimen 1, fixed at a clamping point 1' in a clamping device 2 of the clamping field 3, is to be excited in the system almost at its system natural frequency by active load introduction devices with actuators 5B and 5A, respectively, in the pivot and impact directions. The actuator 5A is connected to the clamping field 3 via a joint 11N. At the other end, a joint 11M connects the actuator 5A to a load frame 4A. The load introduction device with the actuator 5B is also connected to the clamping field 3 via a joint 11L. At the other end, a joint 11K connects the actuator 5B to a lever arm 9C which is perpendicular to a Angle beam 16 is connected.This is supported by hinge 10C. The load from actuator 5B is transferred via beams 9C and 16 at a right angle to the load application point of actuator 5B, through a rod 8C, to the test specimen 1. For this purpose, rod 8C is connected via a joint 11J to the load frame 4A, which introduces the loads into the test specimen 1.

[0053] The test specimen 1, or in this case the rotor blade, is equipped with a further load frame 4F, which can move almost vertically upwards and downwards relative to an initial position 4F' of the longitudinal axis of the test specimen 1 by deformation of the rotor blade. This load frame 4F is connected to the rod 8A via a joint 11P and thus transmits the forces from the test specimen 1 to the rod 8A. The line of action of the force on the rod in its rest position is designated 8A' and is advantageously aligned normal to the longitudinal axis of the test specimen in its initial (unloaded) position 4F' to avoid parasitic forces. The rod 8A is connected to the lever arm 9A via a further joint 11Q. The lever arm 9A is supported at one end by a hinge 10D to allow tilting of the lever arm. A plate assembly 20C allows adjustment of the height of the support.This allows the joints / hinges 10D, 11A, 11Q to be advantageously positioned in a common effective lever arm line 9A', which can be aligned orthogonally to the position of one or both of the lines of action 8A' or 8B' to avoid parasitic forces.

[0054] At a point between its ends, for example in its middle, the lever 9A is connected via a joint 11A to another rod 8B, which is connected via a joint 11B to an elastic element 14, shown here as a spring module 14 with leaf springs, and thus transmits forces between the lever arm and the spring module.

[0055] The spring module 14 is supported at both ends by hinge joints 10A and 10B, which are connected to the clamping frame 3. The spring moves almost symmetrically about its axis 14' in its rest position, which is almost parallel to the lever arm axis 9A'. At one end of the spring, a shackle 13 is additionally inserted between the hinge joint 10E, which is fixedly connected to the clamping frame, and the hinge joint 10B, which is fixedly connected to the spring module. This allows the spring to be mounted as a floating bearing, thus permitting horizontal displacement of the joint 10B when the spring deflects. The rest position of the spring can also be asymmetrical to apply a preload.

[0056] The aim of arranging the individual components, in particular the directions of movement of the rods for connecting the components, is to design them in such a way that the greatest possible force acts normal to the longitudinal axis of the test specimen / rotor blade and parasitic forces (losses) are minimized.

[0057] Several variations of the arrangement shown are possible.

[0058] Besides the in Fig. The variant shown in step 1 shows Fig. Figure 2 shows a variant of the setup in which the lever 9A and the spring module 14, with their respective longitudinal axes 9A'' and 14'', are aligned transversely to the plane of the drawing and to a vertically oriented plane containing the longitudinal axis of the test specimen. This variant of the alignment represents another possibility in which the joints 11A and 11Q, as well as the hinge joint 10D, can be arranged on a common straight line 9A'' using the plate assemblies 20C. The advantage of this arrangement is that the rod 8A is tilted only in the plane of the drawing by movement of the rotor blade 1 in the y-direction / horizontal direction, which allows the joint 11Q to also be designed as a hinge joint. In addition, this alignment along the rotor blade 1 is more space-saving, which allows more load elements of the test fixture to be placed closer together.

[0059] Fig. Figure 3 shows a variant of the test device setup in which the longitudinal axis of the lever arm 9A is aligned transversely to the longitudinal axis 14'' of the spring module 14. The longitudinal axis 14'' of the spring module 14 is aligned transversely to the longitudinal axis of the rotor blade 1. The axis of rotation 10D'' of the hinge joint 10D at one end of the lever arm 9A is aligned parallel to the longitudinal axis 14'' of the spring module 14 and runs perpendicular to the line of action of the force that is transmitted from the spring module 14 to the lever 9A. Since in Fig. 3. Since the longitudinal axis of the lever arm 9A does not lie in the drawing plane, the hinge axis 10D'' does not run normal to the drawing plane and is therefore explicitly shown as a dashed line.

[0060] Another variant, not shown, provides for the alignment of the lever 9A transversely to the longitudinal axis of the rotor blade 1 and the alignment of the longitudinal axis of the spring module 14 transversely to the longitudinal axis of the lever 9A, which may be advantageous under certain conditions in terms of the space utilization of the test setup or in terms of the utilization of the joint angles.

[0061] Besides variants where the joints / hinge joints 10D, 11A, and 11Q form an almost continuous line, other variants are conceivable that generate the lowest possible parasitic forces. In these variants, the connecting line between the joints / hinge joints 10D and 11A (effective lever arm of the spring) can be aligned orthogonally to the line of action 8B'', and this line in turn can be aligned orthogonally to the longitudinal axis 14' or 14'' of the spring module. Simultaneously, the connecting line between 10D and 11Q (effective lever arm of the rotor blade) can be aligned orthogonally to the line of action 8A'', and this line in turn can be aligned orthogonally to position 4F', the longitudinal axis of the rotor blade 1 in its rest position.

[0062] Mathematically speaking: The position 4F' of the longitudinal axis and the position of the longitudinal axis of the spring module 14' (or 14'') should each be parallel to a plane defined by the hinge axis in 10D' and the respective effective lever (10D-11Q for 4F' or 10D-11A for 14' or 14''). The respective rod (8A for 4F' or 8B for 14' or 14'') has its longitudinal axis perpendicular to the respective plane.

[0063] In principle, all possible angular alignment combinations between test body / rotor blade 1, lever 9A and spring module 14 are feasible within the framework of the test device according to the invention.

[0064] Fig. Figure 4 shows a detailed perspective view of a spring module 14 integrated into the test device. It illustrates one possible configuration of clamping devices / clamps 15A, 15B, 15C for the individual spring elements forming a spring assembly 21. In the example shown, the clamps are located at the ends and in the middle of the spring elements 14A, 14B, 14C, 14D, each of which is designed as a leaf spring with a rectangular cross-section. Further possible cross-sectional configurations of the spring elements are described in the Fig. 23, Fig. 24, Fig. 25, Fig. 26, Fig. 27, Fig. 28, Fig. 29, Fig. 30 to Fig. 31 is shown and explained further below. It is in the Fig. Figure 4 shows, by way of example, that the spring element 14B is wider and therefore stiffer than the other spring elements. By combining spring elements of different widths and stiffnesses, a desired overall stiffness of the spring module 14 can be achieved. The longitudinal axis of the spring module is denoted by 14'.

[0065] The lever arm 9A is in the Fig. Figure 4 shows an exemplary construction consisting of two double-T-shaped metal profiles 22A, 22C, which are provided with stiffening plates 17A, 17B. This results in high stiffness with high material utilization. The support of the lever arm 9A at the edge of the lower stiffening plate 17B is achieved via hinges 10D and plate assemblies 20C on the support frame 23, which is realized with the beams 18A, 18B, 18C, 18A', 18B'. The beams 18A, 18B, 18A', 18B' are connected to the clamping span 3 via plate assemblies 20A, 20B. An inclination of the support frame 23 about the longitudinal axis 14' of the spring module 14 can be achieved via angle plates 19A, 19B and the corresponding thickness of the (number of plates) plate packages 20A, 20B, which can be used to reduce forces in undesired directions.

[0066] Fig. 5 shows a side view of the in Fig. The structure shown in Figure 4 illustrates the possible adjustment of the height of the beams 18A, 18B and the inclination of the support frame by means of sheet metal / plate packages 20A, 20B and angle plates 19A, 19B. The thickness of the sheet metal / plate packages 20C can also be adjusted so that the joints / hinge joints 11Q, 11A, 10D lie almost on an axis 9A' (optimal position of axis 9A', see Figure 4). Fig. 1).

[0067] Fig. Figure 6 shows a frontal view of a setup according to Fig. 3. In Fig. Figure 6 illustrates that the support frame 23 can be tilted using angle plates 19A, 19A' to follow the tilt of the rotor blade around its longitudinal axis (pitch angle) and thus align the axis 10D'' of the hinges 10D and 10D', and consequently the direction of movement of the lever, parallel to the line of action 8A'' of the rod 8A. This reduces undesired lateral forces on the rotor blade. The spring module 14 remains in a straight, non-tilted position. 11B designates a spherical bearing that compensates for the tilt of the support frame 23 relative to the spring module 14 and compensates for an angular deviation of up to 4 or 8 degrees with a fixed connection.

[0068] Fig. Figure 7 shows a variant with a tilted support frame 23 via the angle plates 19C, 19C' and an inclined position of the spring module 14 such that the inclined position of the spring module 14 corresponds to the inclined position of the support frame 23. This advantageously reduces lateral forces on the hinges 10A, 10A'.

[0069] Fig. Figure 8 shows an embodiment with an extended lever arm 9A', wherein the connection point of the rod 8B is shifted to the opposite side of the support frame 23. A sheet metal stack 20C'' is provided between the lever 9A' and the joint 11A. This variant has the advantage that the space between the spring and the lever below the rod 8A remains free and can be used for other elements of the test device not shown.

[0070] Fig. 9 shows another variant differing from Fig. 5. Each of the clamps 15A, 15B and 15C can be arbitrarily positioned longitudinally along the spring module 14 relative to the one in order to produce desired stiffnesses and lever ratios. Fig. The arrangement shown in Figure 5 can be moved and fixed. The respective joints / hinge joints 10A, 10B, and 11B are moved accordingly. The clamp 15B can be moved asymmetrically between the clamps 15A and 15C. The joint 11A is moved further in the direction of the joint 11Q. This embodiment thus demonstrates further adjustment options for the test device. In this variant, the joints / hinge joints 11A, 11Q, and 10D can be realized lying almost in a straight line. In addition, the support 22A can be moved between the plates 17A and 17B to further adjust the lever ratio and thereby reduce the rotational inertia of the lever arm 9A.

[0071] The Fig. Figures 10-12 show variants of load introduction into the spring module 14 by means of a four-point bending, which reduces the shear forces in the area of ​​the support. The hinge joints 11B' and 11B'', attached to the clamps 15B' and 15B'', serve this purpose.

[0072] In the variants of Fig. 10 and Fig. 11. The load is introduced into the spring module via a fixed bearing and a floating bearing. Here, 15B' is designed as a fixed bearing and 15B'' as a floating bearing. Fig. Figure 10 shows a variant in which the load is applied via a crossbeam 27. This crossbeam 27 is connected to the lever 9A via a further hinge 11B and the rod 8B as well as the joint 11A.

[0073] In Fig. 11. The load is introduced via a stiffening plate 29 with a recess, and both the crossbeam 27 and the hinge 11B and rod 8B are omitted, which makes the construction lighter and more robust than the variant shown in Fig. 10 is shown.

[0074] Fig. Figure 12 shows an embodiment in which a fork 28 is attached to the hinge joint 11A, to which two rods 8B' and 8B'' are pivotally connected. These are in turn connected to the hinge joints 11B' and 11B'' and thus transmit the load to the spring module 14 via the clamps. Here, the floating bearing clamp 15B'' is made of Fig. 10 replaced by a fixed bearing clamp 15B'''.

[0075] Fig. Figure 13 shows a variant of the spring module with one-sided clamping in the bearings 10A, 10B, and 10E. In this example, this is achieved by using two adjacent supports to realize the clamping. One-sided support allows for greater freedom in positioning the spring module 14 and the lever arm 9A, enabling more efficient use of the available space. This allows the spring module to accommodate larger deformations but smaller forces. A disadvantage of this embodiment is the increased lateral forces on the bearing points.

[0076] Fig. Figure 14 shows a variant of a lever 9A composed of tubular profiles 24B, 24C, 24D, 24E. Tubular profiles with different cross-sections or increasing diameters are connected to one another or slid into one another and positioned such that the diameter, and thus the stiffness, is greater where the bending moment is greater. The lever is preferably supported by clamps or clamps 25A, 25B to which the hinges 11Q, 11A, 10D are connected. This composite lever 9A connects the spring module (not shown) via the rod 8B and the hinge joint 11A to the hinge joint 11Q and the rod 8A for load transmission into the test specimen. The hinge 10D serves to support the lever 9A. In this embodiment, the mass of the lever 9A can advantageously be reduced where a large acceleration acts (in the region of the hinge joint 11Q).

[0077] Fig. 15 shows a variant of a in Fig. 14 Lever arm 9A made of tubular profiles shown in frontal view.

[0078] Fig. Figure 16 shows a side view of a spring element 14A in sandwich construction with scarfed face sheets 31 and a core 32 with a core thickness that is constant along its length, to increase the profile height at the center of the spring element with respect to its longitudinal direction. The increase in profile height is achieved via a scarf angle 30 in a plane in the direction of the thickness.

[0079] This results in the stiffness of the spring element 14A being greatest where the deflection is greatest.

[0080] Fig. Figure 17 shows a side view of a spring element 14A in sandwich construction with a scarfed (angle 30°) core 32 to increase the profile height in the spring module center. In this case, cover layers 31 of constant thickness, for example pultrudate, can be used, which simplifies manufacturing.

[0081] Fig. Figure 18 shows a variant of the spring element 14A with connected or nested tube elements 24J, 24K, 24L, 24M with an increasing diameter towards the spring center. The tube elements can be manufactured, for example, in a winding process. This design enables a very lightweight construction with simultaneously high stiffness.

[0082] Fig. 19 shows a variant of the in Fig. Figure 15 shows a structure in which the cover layers 31 at the ends and in the middle of the spring element 14A are provided with flattened areas or areas of constant thickness 33, 33', 33'' to allow the clamps to be mounted there. Additional areas of constant thickness can also be provided along the spring element to allow clamps to be mounted at various locations.

[0083] The Fig. Figures 20 and 21 each show a top view of a spring element 14A with a width that varies along the longitudinal direction in order to achieve maximum stiffness in the area of ​​greatest deflection in the middle region of the spring element. The change in width occurs at a scarf angle 34 in a plane in the longitudinal direction. In addition to a variant with straight edges ( Fig. 19) A variant with a curved width profile 35 is also conceivable in order to achieve a more uniform stiffness profile.

[0084] Fig. Figure 22 shows a perspective view of a profile of varying thickness and width along its length, using the example of a box section 36, which is narrower and taller in the middle of its length than at the ends. This makes it possible to increase the stiffness towards the center of the spring element, where the deflection is greatest.

[0085] Fig. Figure 23 shows a spring module with four spring elements 14A, 14B, 14C, 14D, each with a rectangular cross-section, constructed in a sandwich design with a core 32, for example, made of foam or lightweight wood (balsa) and with outer layers 31 made of a fiber-reinforced plastic. The individual spring elements are arranged in the spring module 14 with lateral spacing between them, as viewed in cross-section. The width of the individual spring elements can vary so that their properties can be selected to match the desired properties of the spring assembly. These elements are connected by a clamp 15A with clamping bars 15D, 15E, which are connected to each other at several points, for example at their ends, by means of connecting elements 100A, 100B. The connecting elements can, for example, include threaded rods or screws and nuts, so that the spring elements can be reliably held between the clamping bars by means of a force-fit connection.

[0086] Fig. Figure 24 shows a spring module with five spring elements 14A, 14B, 14C, 14D, 14E, each with a trapezoidal cross-section in a sandwich construction with a core. The trapezoidal shape allows for better interlocking of the individual spring elements.

[0087] Fig. Figure 25 shows a spring module made of spring elements 14A, 14B, 14C, 14D, 14E in the form of tubular profiles, which are manufactured, for example, in a winding process and are clamped to form a spring module between the clamping beams 15D, 15E.

[0088] The Fig. Figures 26-31 show variants for individual spring elements 14A, each in cross-section.

[0089] Fig. Figure 26 shows a single spring element 14A in sandwich construction with integrated webs 37, 37', 37'' at the edge and in the middle, viewed in cross-section, to increase the shear stiffness; compared to the one in Fig. In the embodiment shown in Figure 23, in which the spring elements themselves do not have webs 37, a more shear-resistant and therefore lighter core 32 can be used, for example. The cover layer is designated 31.

[0090] Fig. Figure 27 shows a sandwich element manufactured using a winding method, with a wound core 32, which enables efficient and automated manufacturing.

[0091] Fig. Figure 28 shows a variant of a spring element 14A in the form of a tube with individual, for example cylindrical, recesses 38 in the tube wall (modeled as a bionic profile on the shape of a plant stem) in order to generate very high stiffness at low weight.

[0092] Fig. Figure 29 shows a spring element 14A in the form of a double-T profile, for example from a pultrusion process, which can originate from an automated and therefore cost-effective manufacturing process.

[0093] The Fig. Figures 30 / 31 show pultruded cross-sections of a figure-eight profile. These can be notched, rolled, or drawn from a strand. One variant is shown with a solid cross-section of 40 mm. Fig. 30 and a variant with a hollow cross-section of 40' in Fig. 31. These profiles show advantages against shear buckling.

[0094] In the Fig. Figure 32 shows a spring module 14 in which a number of 5 spring elements 14F, 14G, 14H, 14i, 14J are arranged both side by side and one above the other in cross-section. Such a combination allows, for example, a desired ratio of the stiffnesses of the spring module in the various directions 101, 102 perpendicular to its longitudinal direction to be set in the case of a biaxial load. Three clamping beams 15G, 15H, 15i, aligned parallel to each other, are provided for clamping the spring elements 14F, 14G, 14H, 14i, 14J. The spring elements 14F and 14G are clamped between the clamping beams 15G, 15H, while the spring elements 14H, 14i, and 14J are clamped between the clamping beams 15H and 15i.The clamping beams each have adhesive or compensating layers 103, 104 on their sides facing the spring elements. These layers are made of a material that is softer than the material of the clamping beams and can compensate for different heights of the spring elements. The compensating layers 103, 104 can, for example, be made of a hard rubber or a plastic. Instead of three clamping beams, more than three, for example four or five clamping beams with spring elements arranged between them, can also be used.

[0095] In the Fig.Figure 33 shows a spring module 14 with a clamping device 15L, which has slightly curved clamping beams 15J, 15K between which spring elements 14i, 14J are clamped. The curvature of the clamping beams is somewhat exaggerated for clarity. Even a slight curvature of the clamping beams significantly stiffens the spring module when using identical spring modules. Furthermore, such an arrangement allows the ratio of the stiffnesses of the spring module in the various directions 101, 102 perpendicular to its longitudinal direction to be adjusted. The distance between the clamping beams 15J, 15K can be constant along the clamping beams, so that spring elements with a rectangular cross-section can be used.

Claims

[1] Test device for the mechanical testing of a beam-shaped test specimen (1), in particular a rotor blade, comprising a clamping device (2) anchored in a clamping field (3) for clamping the beam-shaped test specimen (1) at a clamping point (1') of the beam-shaped test specimen (1) one or more coupling elements (4A, 4F) connected to the beam-shaped test specimen (1), in particular load frames, one or more active load introduction devices (5A, 5B) each connected to a coupling element, as well as one or more passive load introduction means connected to a coupling element, at least one of which has a spring device connected to the clamping field (3), wherein the spring device comprises a spring module (14) with several spring elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) connected mechanically in parallel to each other and the spring module (14) comprises spring elements in the form of one or more flexible beam elements arranged in parallel to each other, characterized by , that on the spring module (14) one or more clamping devices (15A, 15B, 15B', 15B'', 15B''', 15C, 15F, 15L) are provided, each having two clamping beams (15D, 15E, 15G, 15H, 15i, 15J, 15K) that can be connected or joined by connecting elements (100A, 100B), between which the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) can be clamped. [2] Test device according to claim 1, characterized by , that the spring module (14) is connected at at least one of its ends to the clamping field (3) by means of a joint (10A, 10E) or a hinge joint. [3] Test device according to one of claims 1 or 2, characterized by , that the spring module (14) is connected at one of its ends by means of a shackle (13) to a joint (10E) or hinge joint which is connected to the clamping field (3). [4] Test device according to any one of claims 1 to 3, characterized by , that the spring module (14) has one or more releasable clamping devices (15A, 15B, 15B', 15B'', 15C, 15F, 15L) in which one or more flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) can be clamped. [5] Test device according to claim 4, characterized by , that at least one clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) is displaceable along the spring module (14) and is configured to clamp the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) of the spring module (14) selectively at one of several positions. [6] Testing device according to claim 4 or 5, characterized by , that at least one clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) is connected to the clamping field (3) by means of a joint (10A, 10E) or a hinge joint and / or that at least one clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) is connected to a joint (10E) or hinge joint which is connected to the clamping field by means of a shackle (13). [7] Test device according to claim 4, 5 or 6, characterized by , that at least one clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) is connected to the test specimen (1) by means of a transmission element, in particular by means of a lever (9A). [8] Test device according to any one of claims 1 to 6, characterized by, that the spring module (14) is connected to the clamping field (3) at only one or at least two points along the longitudinal direction of the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J). [9] Test device according to any one of claims 1 to 8, characterized by , that a clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) connected to the test specimen (1) is located in the longitudinal direction of the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) of the spring module (14) between two clamping devices (15A, 15B, 15B', 15B'', 15C, 15F, 15L) connected to the clamping field (3) or that the spring module (14) is only clamped on one side to the clamping field (3) and a clamping device (15A, 15B, 15B', 15B'', 15C, 15F, 15L) connected to the test specimen (1) clamps the spring module (14) clamps at a point along the longitudinal direction of the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) of the spring module (14). [10] Testing device according to any one of claims 1 to 9, characterized by , that the spring module (14) is connected to the test specimen (1), in particular a rotor blade or a lever arrangement (9A) connected to the rotor blade, at only one or at least two points along the longitudinal direction of the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J). [11] Testing device according to any one of claims 1 to 10, characterized by, that several flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) are arranged parallel to each other in a spring module (14) and that at several or all locations along the longitudinal direction of the flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) several or all beam elements 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) have the same thickness in the direction of the mechanical load for which the spring module (14) is intended, such that they are jointly clamped by a clamping device (15A, 15B, 15B', 15B'', 15B''', 15C, 15F, 15L) can be clamped. [12] Testing device according to any one of claims 1 to 11, characterized by , that in a spring module several differently stiff flexible beam elements (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 14i, 14J) are arranged parallel to each other.

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