Fixing structure and testing device suitable for testing buckling performance of elliptical thin plate

Abstract

The utility model discloses a fixing structure suitable for an elliptical thin plate buckling performance test. The fixing structure comprises a fixing frame, a clamping plate, an arc-shaped clamp and a thin plate test piece, the peripheries of the clamping plates are connected with the fixed frame, and elliptical openings are formed in the centers; the peripheral side area of the thin plate test piece is clamped in the clamping plate, and the central area of the thin plate test piece is exposed at the elliptical opening; the arc-shaped clamp is annularly arranged on the inner edge of the oval opening and connected with the clamping plate. The two groups of arc-shaped clamps clamp the thin plate test piece from two sides to form a circumferentially continuous clamped boundary, and an elliptical test thin plate is equivalently constructed on the thin plate test piece. The utility model further provides a testing device suitable for testing the buckling performance of the elliptical thin plate, the testing device is provided with the fixing structure, the testing device further comprises a loading unit, a monitoring unit and an initial defect inspection system, and three-dimensional data acquisition is carried out on the elliptical test thin plate.

Description

Technical Field

[0001] This utility model relates to the field of testing equipment technology, and in particular to a testing device suitable for testing the buckling performance of elliptical thin plates. Background Technology

[0002] In the manufacturing of high-end equipment such as aerospace, elliptical thin plates are widely used in critical load-bearing structures such as fuselage skin and fuel tank bulkheads due to their excellent aerodynamic performance and lightweight characteristics. These thin plates typically have a thickness much smaller than their length and width, making them highly susceptible to buckling failure under axial compressive loads. Physical experimental studies of the buckling performance of elliptical thin plates present certain challenges due to their unique geometric characteristics: traditional testing equipment struggles to achieve continuous and stable clamping of the elliptical boundary, and mechanical clamps can easily cause edge stress concentration or introduce unnecessary constraints, leading to distortion in the load simulation.

[0003] In existing technologies, researchers typically use simplified boundary conditions or finite element simulations to replace physical experiments. However, the idealized assumptions about boundary conditions can lead to deviations between experimental data and actual working conditions. Some technologies or attempts have been made to fix elliptical thin plates using customized clamps, but these suffer from uneven clamping force distribution and discontinuous boundary constraints. These limitations severely restrict in-depth research on the buckling performance of elliptical thin plates and also affect the reliability of structural optimization design. How to construct an experimental device that can accurately simulate elliptical boundary constraints while possessing high testing accuracy has become a pressing technical challenge in this field. Utility Model Content

[0004] The main technical problem to be solved by this utility model is to provide a test device suitable for testing the buckling performance of elliptical thin plates, so as to accurately test the buckling performance of elliptical thin plates.

[0005] To solve the above-mentioned technical problems, this utility model provides a fixing structure suitable for buckling performance testing of elliptical thin plates, including a fixing frame, a clamping plate, an arc-shaped clamp, and a thin plate specimen;

[0006] The clamping plate is connected to the fixed frame on its outer periphery and has an elliptical opening in the center. The peripheral area of ​​the thin plate specimen is clamped in the clamping plate, and the central area is exposed at the elliptical opening. The arc-shaped clamp is arranged circumferentially on the inner edge of the elliptical opening and is connected to the clamping plate. The two sets of arc-shaped clamps clamp the thin plate specimen from both sides to form a circumferentially continuous fixed boundary, and an elliptical test plate is equivalently constructed on the thin plate specimen.

[0007] In a preferred embodiment, the arc-shaped clamp is provided with a notch at at least one intersection with the major axis of the ellipse.

[0008] In a preferred embodiment, the two sets of arc-shaped clamps located on both sides of the thin plate specimen are made of opposite magnetic materials.

[0009] In a preferred embodiment, the clamping plate has a connecting portion perpendicular to the plate surface at its edge; the connecting portion is connected to the fixed frame via a plurality of first connectors.

[0010] In a preferred embodiment, the edge of the elliptical opening of the clamping plate is provided with a clamp support; the arc-shaped clamp assembly is connected to the clamp support by a plurality of second connectors spaced apart along the circumference.

[0011] In a preferred embodiment, the fixed frame is a rigid spatial frame made of several steel sections connected together, and a horizontal base is provided at the bottom.

[0012] This utility model also provides a test apparatus suitable for testing the buckling performance of elliptical thin plates, including the fixing structure described above; the test apparatus further includes a loading unit and a monitoring unit:

[0013] The output end of the loading unit is connected to the clamping plate and is used to apply a load to the clamping plate along the major or minor axis of the elliptical opening. The monitoring unit is set on any side of the thin plate specimen and is used to collect the deformation data of the elliptical test thin plate during buckling.

[0014] In a preferred embodiment, the testing apparatus further includes an initial defect inspection system for collecting and quantifying the initial geometric defects of the elliptical test plate.

[0015] In a preferred embodiment, the monitoring unit includes a three-dimensional full-field strain-deformation measurement system.

[0016] In a preferred embodiment, the loading unit includes a servo actuator; the output end of the servo actuator is fixedly connected to the top of the clamping plate via a rigid connector.

[0017] Compared with the prior art, the technical solution of this utility model has the following beneficial effects:

[0018] The fixing structure provided by this utility model cleverly uses the magnetic attraction of the arc-shaped clamp to non-insertally hold a square thin plate specimen. By constructing an ideal fixed boundary in an elliptical shape, an equivalent elliptical test thin plate is generated. This continuous and stable ideal fixed boundary not only ensures that the stress simulation of the elliptical test thin plate matches the assumed conditions but also avoids potential structural damage to the thin plate specimen. The fixing structure is simple in architecture, stable in connection, and direct in force transmission, and the test operation is simple and quick. Based on the fixing structure, the test device uses an initial defect inspection system, a loading unit, and a monitoring unit to comprehensively and three-dimensionally collect data from the elliptical test thin plate, providing sufficient data for subsequent test analysis. In summary, the test device provides an effective experimental means for the buckling study of elliptical thin plates and has high technical reference value. Attached Figure Description

[0019] Figure 1 This is a schematic elevation view of the fixing structure described in Embodiment 1 of this utility model;

[0020] Figure 2 This is a partial cross-sectional view of the clamping plate described in Embodiment 1 of this utility model:

[0021] Figure 3 This is a plan view of the arc-shaped clamp described in Embodiment 1 of this utility model;

[0022] Figure 4 This is a schematic diagram of the monitoring unit and initial defect inspection system described in Embodiment 2 of this utility model.

[0023] The markings in the figure are as follows: 11-fixed frame, 111-transverse base, 12-clamping plate, 121-elliptical opening, 122-connecting part, 13-clamp support, 14-arc clamp, 141-notch, 15-first threaded fastener, 16-second threaded fastener, 2-thin plate specimen, 21-elliptical test thin plate, 31-servo actuator, 32-rigid connector, 4-three-dimensional full-field strain-deformation measurement system (DIC), 5-3D scanner. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0025] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped with", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0027] Example 1

[0028] like Figures 1-3 As shown, this utility model embodiment provides a fixing structure suitable for testing the buckling performance of elliptical thin plates, including a fixing frame 11, a clamping plate 12, an arc-shaped clamp 14, and a thin plate specimen 2.

[0029] like Figure 1 As shown, the fixed frame 11 is a rigid spatial frame formed by welding or bolting several steel sections, and is placed on the test platform via a horizontal base 111 at the bottom. The clamping plate 12 is square, and its outer perimeter is fitted with several first threaded fasteners 15 spaced apart, which are installed inside the square fixed frame 11. Specifically, as shown... Figure 2As shown, the clamping plate 12 has a connecting portion 122 perpendicular to the plate surface direction at its edge. The connecting portion 122 has several threaded holes along the thickness direction on both sides of the clamping plate 12. The first threaded fastener 15 passes through the threaded holes and is detachably connected to the fixing frame 11. As shown, the clamping plate 12 has an elliptical opening 121 in its central region, and a clamp support 13 is provided at the edge of the elliptical opening 121. The arc-shaped clamp 14 is circumferentially disposed on the inner edge of the elliptical opening 121 and is connected to the arc-shaped clamp 14 by several second threaded fasteners 16 spaced apart along the circumference. It should be understood that, to achieve the clamping and fixing function, the clamping plate 12 is composed of two plates. Correspondingly, a set of clamp supports 13, arc-shaped clamps 14, and corresponding second threaded fasteners 16 are also provided on each side of the clamping plate 12. In other embodiments, the first threaded fastener 15 and the second threaded fastener 16 can be replaced by snap fasteners, rivets, etc., and are therefore referred to as the first connector and the second connector, respectively, in this document.

[0030] In this embodiment, the thin plate specimen 2 is square, with its peripheral area clamped and fixed within the clamping plate 12, while its central area is exposed at the elliptical opening 121. Preferably, in actual testing, various measures can be taken to assist in clamping the thin plate specimen 2. For example, threaded fasteners perpendicularly penetrating the clamping plate 12 can be used to compress the clamping plate 12, or two sets of dissimilar magnetic blocks or abutment devices can be used to continuously apply force from both sides to increase the clamping force. This embodiment does not limit the specific auxiliary clamping measures. Within the area of ​​the elliptical opening 121, two sets of arc-shaped clamps 14 clamp the thin plate specimen 2 from both sides, forming a circumferentially continuous ideal fixed boundary, so as to equivalently construct an independently stressed elliptical test thin plate 21 on the thin plate specimen 2. It should be noted that the "elliptical test thin plate 21" refers to the equivalently constructed elliptical independent stressed body, while "thin plate specimen 2" refers to the integral, square specimen. Please distinguish between them in subsequent readings. In this embodiment, two sets of arc-shaped clamps 14 located on both sides of the thin plate specimen 2 are made of opposite magnetic materials, and clamp and fix the thin plate specimen 2 by opposing magnetic attraction. Compared with traditional clamping methods such as threaded fasteners, this non-insertion clamping design has multiple advantages: it constructs a continuous and stable ideal fixed support boundary, avoids stress concentration, ensures that the stress simulation of the elliptical test thin plate 21 matches the assumed conditions, and also avoids possible structural damage to the thin plate specimen 2. It should be understood that the contour of the arc-shaped clamp 14 matches the theoretical boundary of the elliptical test thin plate 21, and it can be modularly designed according to specific experimental needs. Preferably, the arc-shaped clamp 14 is provided with a rubber ring on the side facing the thin plate specimen 2, which not only makes the arc-shaped clamp 14 more fully engage the thin plate specimen 2, but also increases the friction between the two at the contact surface.

[0031] As an equivalent alternative to this embodiment, in other embodiments, the arc-shaped clamp 14 and the clamp support 13 are connected by an elastic element. The elastic element is pre-compressed to form an elastic restoring force perpendicular to the thin plate specimen 2, so as to push against the arc-shaped clamp 14 from both sides toward the thin plate specimen 2, thereby achieving clamping and fixing of the thin plate specimen 2.

[0032] When the arc-shaped clamp 14 is compressed, it needs to undergo a small displacement along its long axis to transfer the axial force to the elliptical test plate 21. Therefore, as Figure 3 As shown, the arc-shaped clamp 14 has notches 141 at at least one intersection with the major axis of the ellipse. In this way, when constrained by the two side fixing frames 11 and unable to expand outward in the minor axis direction, the arc-shaped clamp 14 can still retract inward in the major axis direction through the two notches 141 at the top and bottom, stably transmitting the force to the elliptical test plate 21. It should be understood that this is only a preferred solution from a structural perspective. In other embodiments, the arc-shaped clamp 14 is made of a micro-elastic material, which can also retract inward along the major axis direction under load.

[0033] In related experiments, elliptical thin plates are difficult to fix directly and continuously due to their special contours. If multi-point circumferential fixing is used, stress concentration at the fixing points can easily lead to simulation distortion. This utility model embodiment adopts an innovative approach, cleverly using the magnetic attraction of the arc-shaped clamp 14 to non-insertively hold the square thin plate specimen 2. By constructing an ideal elliptical fixed boundary, an equivalent elliptical test thin plate 21 is generated. This continuous and stable ideal fixed boundary not only ensures that the stress simulation of the elliptical test thin plate 21 matches the assumed conditions but also avoids potential structural damage to the thin plate specimen 2. The fixing structure is simple, the connection is stable, the force transmission is direct, and the experimental operation is simple and quick, possessing high reference value and promotional benefits.

[0034] Example 2

[0035] like Figures 1-4 As shown in the figure, this utility model embodiment provides a test device for testing the buckling performance of an elliptical thin plate, configured with the fixing structure described in Embodiment 1. The test device also includes a loading unit, a monitoring unit, and an initial defect inspection system.

[0036] The loading unit is installed on top of the fixed frame 11. The loading unit is an MTS servo loading actuator (hereinafter referred to as servo actuator 31), with a range of 50kN, and is equipped with a data recording system that can record changes in axial compressive load and displacement in real time. The output end of the servo actuator 31 acts on the top of the clamping plate 12 through a rigid connector 32. Specifically, the rigid connector 32 is welded from thick steel plate, and its bottom is connected to the clamping plate 12 through several first threaded fasteners 15. The servo actuator 31 applies force to the clamping plate 12 along the major axis of the elliptical test plate 21, and the clamping plate 12 transmits this force to the arc-shaped clamp 14 to compress the thin plate specimen 2 within the range of the elliptical opening 121, causing it to buckle. It should be understood that the loading direction of the servo actuator 31 on the clamping plate 12 can be adjusted according to the specific test requirements. In other embodiments, it can also apply a load to the clamping plate 12 along the minor axis of the elliptical test plate 21.

[0037] The monitoring unit is located on any side of the thin plate specimen 2 and is used to collect deformation data of the elliptical test thin plate 21 during buckling. Specifically, in this embodiment, the monitoring unit adopts a three-dimensional full-field strain-deformation measurement system 4 (DIC). After continuously photographing and measuring the elliptical test thin plate 21 under test, the full-field strain distribution of the elliptical test thin plate 21 and the spatial displacement of the preset target point are obtained based on digital image technology.

[0038] The initial defect inspection system includes a 3D scanner 5, which scans the surface of the thin plate specimen 2 to form a real three-dimensional model. Then, this real three-dimensional model is compared with the theoretical model drawn by three-dimensional drawing software to accurately quantify the initial geometric defects of the elliptical test thin plate 21.

[0039] The specific testing method for the aforementioned experimental apparatus is described below. The method includes the following steps:

[0040] Step 1: Clamp the outer region of the thin plate specimen 2 in the clamping plate 12, and clamp the thin plate specimen 2 along the inner edge of the elliptical opening 121 using two sets of arc-shaped clamps 14 to equivalently construct an elliptical test thin plate 21.

[0041] Step 2: Use a 3D scanner 5 to form a three-dimensional model of the elliptical test plate 21, obtain the initial geometric defects of the elliptical test plate 21 through deviation analysis, and record and save the initial geometric defects for subsequent analysis.

[0042] Step 3: Install and debug the three-dimensional full-field strain-deformation measurement system 4, and adjust the camera layout and calibration parameters to ensure measurement accuracy.

[0043] Step 4: Install the loading unit and monitoring unit, and use the servo actuator 31 to apply load to the clamping plate 12 step by step at a fixed loading rate, and monitor the buckling mode of the elliptical test plate 21 and the load-displacement curve changes of the control terminal in real time.

[0044] Step 5: Once the elliptical test plate 21 exhibits structural buckling and loses its load-bearing capacity, loading is immediately stopped, thus completing the axial compression buckling test of the elliptical test plate 21. Finally, the buckling mechanism of the elliptical test plate 21 is analyzed by combining the load history, strain field evolution, and initial geometric defect data.

[0045] The above description is merely a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All technically equivalent modifications made based on the content of the present utility model specification shall fall within the protection scope of the present utility model.

Claims

1. A fixing structure suitable for testing the buckling performance of elliptical thin plates, characterized in that: Includes a fixed frame, clamps, curved fixtures, and thin-plate specimens: The clamping plate is connected to the fixed frame on its outer periphery and has an elliptical opening at its center. The peripheral area of ​​the thin plate specimen is clamped in the clamping plate, and the central area is exposed at the elliptical opening. The arc-shaped clamp is circumferentially arranged on the inner edge of the elliptical opening and is connected to the clamping plate. Two sets of arc-shaped clamps clamp the thin plate specimen from both sides to form a circumferentially continuous fixed support boundary, thus constructing an equivalent elliptical test plate on the thin plate specimen.

2. The fixing structure for testing the buckling performance of elliptical thin plates according to claim 1, characterized in that: The arc-shaped clamp is constructed with a notch at at least one intersection point with the major axis of the ellipse.

3. The fixing structure for testing the buckling performance of elliptical thin plates according to claim 1, characterized in that: The two sets of arc-shaped clamps located on both sides of the thin plate specimen are made of opposite magnetic materials.

4. The fixing structure for testing the buckling performance of elliptical thin plates according to claim 1, characterized in that: The clamping plate has a connecting part perpendicular to the plate surface at its edge; the connecting part is connected to the fixed frame through a plurality of first connectors.

5. The fixing structure for testing the buckling performance of elliptical thin plates according to claim 1, characterized in that: The elliptical opening edge of the clamping plate is provided with a clamp support: the arc-shaped clamping assembly is connected to the clamp support through a number of second connecting members spaced apart along the circumference.

6. The fixing structure for testing the buckling performance of elliptical thin plates according to claim 1, characterized in that: The fixed frame is a rigid spatial frame made of several steel sections connected together, and a horizontal base is provided at the bottom.

7. A testing apparatus suitable for testing the buckling performance of elliptical thin plates, comprising the fixing structure according to any one of claims 1 to 6, characterized in that: It also includes a loading unit and a monitoring unit: The output end of the loading unit is connected to the clamping plate and is used to apply a load to the clamping plate along the major or minor axis of the elliptical opening; the monitoring unit is set on any side of the thin plate specimen and is used to collect the deformation data of the elliptical test thin plate during buckling.

8. The test apparatus for testing the buckling performance of elliptical thin plates according to claim 7, characterized in that: It also includes an initial defect inspection system for collecting and quantifying the initial geometric defects of the elliptical test plate.

9. The test apparatus for testing the buckling performance of elliptical thin plates according to claim 7, characterized in that: The monitoring unit includes a three-dimensional full-field strain-deformation measurement system.

10. A test apparatus for testing the buckling performance of elliptical thin plates according to claim 7, characterized in that: The loading unit includes a servo actuator: the output end of the servo actuator is fixedly connected to the top of the clamping plate through a rigid connector.

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