Composite compression test fixture with simultaneous pressure application
By introducing a clamping block extension and an arc-shaped chamfer into the composite material compression test fixture, combined with a guiding structure, the problems of uneven clamping block load and sample deformation were solved, and high-precision testing under different load conditions was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHAN UNIV OF TECH
- Filing Date
- 2025-06-27
- Publication Date
- 2026-06-26
AI Technical Summary
Existing composite material compression test fixtures suffer from uneven load distribution, stress concentration, and specimen buckling deformation, making it difficult to guarantee test accuracy and reliability under different load scenarios.
A composite material compression test fixture capable of synchronous pressure application was designed. It adopts a clamp block extension and an arc-shaped chamfer structure, combined with a transverse and vertical guide structure to ensure uniform load distribution of the clamp block and parallelism of the specimen, provide a controllable movement path, and avoid loading eccentricity and specimen deformation.
It effectively reduces stress concentration at the ends of the clamping blocks, prevents buckling deformation of the specimen, improves the reliability and accuracy of test results, and adapts to the testing requirements under both large and small load conditions.
Smart Images
Figure CN224416570U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of materials testing, specifically relating to a composite material compression test fixture that can apply pressure synchronously. Background Technology
[0002] With the widespread application of composite materials in wind power generation, aerospace, civil engineering, and other fields, the demand for testing their mechanical properties is constantly increasing. To accurately assess the deformation behavior and bearing capacity of composite materials under compression, specialized clamps are generally used to fix and compress the specimens. When performing compression tests on composite materials, the upper and lower sides of the specimen must be clamped and held, leaving the middle region unclamped (this unclamped region is not reinforced and is therefore considered the effective test area). A test load is then applied to the ends of the specimen, and the stress and strain in the effective test area are measured. To ensure the accuracy of composite material compression tests, the load on the specimen must be kept uniform, avoiding both bending and deformation or damage from excessive clamping force.
[0003] Existing composite material compression test fixtures generally have the following problems: 1) They generally adopt a split clamping structure, which can easily lead to uneven load distribution between the left and right clamping blocks, which in turn can cause buckling instability in the effective test area of the specimen; 2) The rigid contact of the clamping block ends on the specimen can cause stress concentration in the effective test area, thereby changing the thickness of the effective test area and interfering with the true data.
[0004] Furthermore, for wind turbine blades, the strength of the pultruded blade sheet varies greatly in different directions. The 0° direction requires a large load for compression testing, while the 90° direction requires a smaller load. In high-load scenarios, even with synchronous structures such as guide columns, it is difficult to withstand excessive loads, while in low-load scenarios, it is difficult to guarantee test accuracy. Utility Model Content
[0005] The purpose of this invention is to provide a composite material compression test fixture that can apply pressure synchronously. This fixture can effectively reduce stress concentration at the end of the clamping blocks in the effective test area of the specimen, reduce buckling and edge deformation, and enhance the reliability of the test results. The load distribution of the left and right clamping blocks of this fixture is uniform, and the load is transmitted synchronously to avoid the influence of load eccentricity on the test results, and ensure that there is no buckling deformation in the middle test area.
[0006] The technical solution adopted in this utility model is:
[0007] A composite material compression test fixture capable of synchronous pressure application includes a base frame and clamping blocks. The base frame includes a base plate that can be mounted on a test bench, a back plate connected to the base plate, and two side plates. Two pairs of clamping blocks are arranged symmetrically vertically, and each pair of clamping blocks is arranged symmetrically horizontally. The two upper and lower clamping blocks on one side are slidably mounted on the same movable plate through a first vertical guide structure. The side of the movable plate is slidably mounted on the back plate through a horizontal guide structure. A clamping power member is installed on the side of the movable plate away from the clamping blocks. The clamping power member faces one side plate and is used to press against the side plate and push the clamping block on that side to clamp. The two upper and lower clamping blocks on the other side are slidably mounted on the same fixed plate through a second vertical guide structure. The fixed plate is mounted on the other side plate. The end of the clamping block near the effective test area extends towards the effective test area to form an extension. The non-clamping side of the extension has an arc-shaped chamfer.
[0008] Preferably, the radius of curvature of the curved chamfer is 10-30mm, the vertical width of the curved chamfer is 2mm-50mm, and the horizontal width of the curved chamfer is 1-10mm.
[0009] Preferably, the clamp is divided into three models according to the applicable pressure load range. The first model of the clamp can be used for pressure loads below 10kN, the second model of the clamp can be used for pressure loads of 10kN-50kN, and the third model of the clamp can be used for pressure loads of 50-500kN. The three models of the clamp have different sizes.
[0010] Preferably, for the first-gear model of the fixture, a single clamping power component is used, with the height position of the clamping power component corresponding to the effective test area; for the second-gear and third-gear models of the fixture, two clamping power components that can be driven synchronously are used, with the height positions of the two clamping power components symmetrical about the effective test area.
[0011] Preferably, the first vertical guide structure includes a vertical guide rail a on the movable plate and vertical sliders a on the side away from the clamping side of the two clamping blocks, with the two vertical sliders a slidingly engaged on the vertical guide rail a; the second vertical guide structure includes a vertical guide rail b on the fixed plate and vertical sliders b on the other side away from the clamping side of the two clamping blocks, with the two vertical sliders b slidingly engaged on the vertical guide rail b.
[0012] Preferably, the lateral guide structure includes at least two lateral guide units distributed vertically, and each lateral guide unit includes a lateral guide rail disposed on the back plate and a lateral slider disposed on the side of the movable plate and slidingly engaged with the lateral guide rail.
[0013] Preferably, the lateral thickness of the movable plate is greater than the lateral thickness of the clamping block, and the side of the movable plate on which the lateral slider is installed is thickened to allow the lateral slider to be installed along its entire length.
[0014] Preferably, the back plate is provided with a limiting plate for limiting the side of the sample.
[0015] Preferably, wear-resistant plates are replaceably provided in the corresponding areas of the sample and the clamping blocks on both sides of the base plate.
[0016] The beneficial effects of this utility model are:
[0017] The clamping blocks of this fixture feature extensions and rounded chamfers, effectively reducing stress concentration at the ends of the clamping blocks within the effective test area of the specimen. This reduces buckling and edge deformation, improves the accurate reflection of stress in the effective test area, and enhances the reliability of the test results. The fixture's lateral guide structure provides a controllable lateral movement path for the movable plate and clamping blocks, ensuring good parallelism during clamping and loading. Furthermore, the two clamping blocks on one side providing clamping force are mounted on the same movable plate, while the two clamping blocks on the other side are mounted on the same fixed plate. This ensures uniform load distribution across the left and right clamping blocks, forcibly and synchronously transferring the load, avoiding eccentric loading that could affect the test results, and ensuring a stress-free test in the central test area. Buckling deformation; the first and second vertical guide structures of the fixture can provide a controllable vertical movement path for the clamping block, maintain the guiding accuracy of the movement, and prevent the sample from shifting laterally or twisting; the structure of the base frame can be installed on the test bench and can also form an integral load-bearing frame, ensuring structural rigidity and deformation resistance, and can provide sufficient reaction force for the clamping power component, so as to maintain structural stability even under large load or long-term use conditions; with the combination of the extension of the clamping block, the arc chamfer, the movable plate, the fixed plate, the lateral guide structure, the first vertical guide structure, and the second vertical guide structure, the fixture can ensure accuracy under both large and small load conditions.
[0018] This application divides the fixture into three levels, allowing you to select the appropriate model according to the testing requirements, thus avoiding low accuracy and fixture damage caused by mismatch. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of a composite material compression test fixture capable of synchronous pressure application in Embodiment 1 of this utility model. The diagram also includes a pressure-applying component at the test bench.
[0021] Figure 2 This is a front view of the composite material compression test fixture capable of synchronous pressure application in Embodiment 1 of this utility model. The figure also includes the pressure-applying component at the test bench.
[0022] Figure 3 This is a rear view of the movable plate and its attachment, and the fixed plate and its attachment in Embodiment 1 of this utility model.
[0023] Figure 4 This is a stress analysis diagram of the specimen during compression testing in Embodiment 1 of this utility model, showing that the extension and the arc-shaped chamfer can effectively reduce stress concentration in the test area.
[0024] Figure 5 This is a schematic diagram of the signal transmission between the pressure component and the clamping power component in Embodiment 2 of this utility model.
[0025] Figure 6 This is a front view of the composite material compression test fixture capable of synchronous pressure application in Embodiment 3 of this utility model. The figure also includes the pressure-applying component at the test bench.
[0026] In the diagram: 1-Pressure component; 2-Clamping block; 3-Clamping power component; 4-Moving plate; 5-Side plate; 6-Base plate; 7-Wear-resistant plate; 8-Limiting plate; 9-Fixing plate; 10-Back plate; 11-Horizontal guide rail; 12-Extension; 13-Chamfered corner; 14-Vertical guide rail b; 15-Vertical slider b; 16-Vertical slider a; 17-Vertical guide rail a; 18-Horizontal slider. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0028] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first vertical guide structure," "second vertical guide structure," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.
[0030] The features and performance of this application will be further described in detail below with reference to the embodiments.
[0031] Example 1
[0032] This embodiment discloses a composite material compression test fixture capable of applying pressure synchronously, such as... Figures 1 to 3 As shown, it includes a base frame, clamping block 2, a first vertical guide structure, a movable plate 4, a transverse guide structure, a second vertical guide structure, a fixed plate 9, and a clamping power component 3; wherein: the base frame includes a base plate 6, a back plate 10, and side plates 5. The base plate 6 can be mounted on the test bench, the back plate 10 is connected to the back side of the base plate 6, and the side plates 5 are connected to both sides of the base plate 6, see Figure 1 , Figure 2 Two pairs of clamping blocks 2 are arranged symmetrically vertically, and each pair of clamping blocks 2 is arranged symmetrically horizontally. The end of the clamping block 2 closest to the effective test area extends towards the effective test area to form an extension 12. The non-clamping side of the extension 12 is provided with an arc-shaped chamfer 13, see Figures 1 to 3 The two clamping blocks 2 on one side are slidably mounted on the same movable plate 4 via the first vertical guide structure. The side of the movable plate 4 is slidably mounted on the back plate 10 via the horizontal guide structure. Figures 1 to 3 The clamping power component 3 is installed on the side of the movable plate 4 away from the clamping block 2. The clamping power component 3 faces one side plate 5. The clamping power component 3 is used to press against the side plate 5 and push the clamping block 2 on the same side to clamp. See Figures 1 to 3 The two clamping blocks 2 on the other side are slidably mounted on the same fixed plate 9 via the second vertical guide structure. The fixed plate 9 is mounted on the plate 5 on the other side. Figures 1 to 3 .
[0033] The clamping block 2 of the fixture is designed with an extension 12 and an arc-shaped chamfer 13, such as Figure 4As shown, this fixture can effectively reduce stress concentration at the end of clamp 2 acting on the effective test area of the specimen, reduce buckling and edge deformation, improve the true stress reflection capability of the effective test area, and enhance the reliability of the test results. The lateral guide structure of this fixture can provide a controllable lateral movement path for the movable plate 4 and clamp 2, ensuring good parallelism during clamping and loading. Furthermore, the two upper and lower clamps 2 on the side providing clamping force are installed on the same movable plate 4, and the two upper and lower clamps 2 on the other side are installed on the same fixed plate 9. The load distribution of the left and right clamps 2 is uniform, forcibly and synchronously transferring the load, avoiding the influence of loading eccentricity on the test results, and ensuring no buckling deformation in the middle test area. The first and second vertical guide structures provide a controllable vertical movement path for the clamping block 2, maintaining the guiding accuracy of the movement and preventing the sample from shifting laterally or twisting. The base frame can be installed on the test bench and also form an integral load-bearing frame, ensuring structural rigidity and deformation resistance. It can provide sufficient reaction force for the clamping power component 3, and maintain structural stability even under heavy loads or long-term use. With the combination of the extension 12 and the arc-shaped chamfer 13 of the clamping block 2, as well as the movable plate 4, the fixed plate 9, the lateral guide structure, the first vertical guide structure, and the second vertical guide structure, the fixture can ensure accuracy under both heavy and light load conditions.
[0034] In this embodiment, the radius of curvature of the arc chamfer 13 is 10-30mm, the vertical width of the arc chamfer 13 is 2mm-50mm, and the horizontal width of the arc chamfer 13 is 1-10mm. The dimensions of the arc chamfer 13 are calculated and designed in combination with various factors such as the fixture material, the sample material, the applied pressure load, and the compressive strength.
[0035] In this embodiment, preferably, as follows: Figures 1 to 3 As shown: The first vertical guide structure includes a vertical guide rail a17 mounted on the movable plate 4 and two vertical sliders a16 respectively mounted on the upper and lower clamping blocks 2 on one side away from the clamping side. The two vertical sliders a16 are simultaneously slidably engaged with the vertical guide rail a17. The second vertical guide structure includes a vertical guide rail b14 mounted on the fixed plate 9 and two vertical sliders b15 respectively mounted on the upper and lower clamping blocks 2 on the other side away from the clamping side. The two vertical sliders b15b are simultaneously slidably engaged with the vertical guide rail b14. This arrangement ensures guiding accuracy and reliability.
[0036] In this embodiment, preferably, as follows: Figures 1 to 3 As shown: The lateral guide structure includes at least two lateral guide units distributed vertically. Each lateral guide unit includes a lateral guide rail 11 mounted on the back plate 10 and a lateral slider 18 mounted on the side of the movable plate 4 and slidingly engaged with the lateral guide rail 11. This arrangement ensures the reliability of lateral movement.
[0037] In this embodiment, preferably, as follows: Figures 1 to 3As shown: The lateral thickness of the movable plate 4 is greater than that of the clamping block 2, which can transmit force more evenly. The side of the movable plate 4 where the lateral slider 18 is installed is thickened to install the lateral slider 18 along its length, which can ensure sufficient sliding pair distance and improve guiding accuracy and reliability.
[0038] In this embodiment, preferably, as follows: Figures 1 to 3 As shown: The back plate 10 is provided with a limiting plate 8 for limiting the side of the sample. The limiting plate 8 can prevent the sample from moving randomly in the front and back directions.
[0039] In this embodiment, preferably, as follows: Figures 1 to 3 As shown: Wear-resistant plates 7 are replaceably provided on the corresponding areas of the sample and the clamping blocks 2 on both sides of the base plate 6. This area is the area of frequent friction between the clamping blocks 2 and the sample. Providing replaceable wear-resistant plates 7 can improve the service life of the base plate 6 and maintain the accuracy of the fixture. The wear-resistant plates 7 can be installed by embedding them into the base plate 6.
[0040] In Example 1, the clamp is suitable for pressure loads of 50-500kN. In this example, as... Figures 1 to 3 As shown: Two clamping power components 3 that can be driven synchronously are used, and the height positions of the two clamping power components 3 are symmetrical about the effective test area. The clamping power components 3 can be hydraulic cylinders.
[0041] Example 2
[0042] This embodiment discloses another composite material compression test fixture capable of simultaneous pressure application, such as... Figure 5 As shown, its difference from Embodiment 1 is as follows:
[0043] 1) The clamping power component 3 is intelligently adjusted by the controller. The controller controls the clamping force of the clamping power component 3 by the feedback of the pressure load or displacement of the pressure component 1. After the clamping power component 3 pushes the clamping block 2 on the side to clamp the sample with a small clamping force, the pressure component 1 begins to apply a vertical downward pressure load to the two clamping blocks 2 on the upper side. Then the clamping force rises synchronously with the pressure load, realizing the linear or nonlinear linkage between the clamping force and the pressure load.
[0044] The workflow of this embodiment is as follows: First, the base plate 6 is securely installed on the test bench and placed below the pressure member 1. Then, the sample is placed between the two clamping blocks 2 on both sides. Then, the controller controls the clamping power member 3 to start. The clamping power member 3 pushes the clamping block 2 on the side where it is located to move to the clamping block 2 on the other side until the sample is clamped with a smaller clamping force. Then, the controller controls the pressure member 1 to start applying a vertical downward pressure load to the two clamping blocks 2 on the upper side. After that, the clamping force is controlled to rise synchronously with the pressure load to realize the linear or nonlinear linkage between the clamping force and the pressure load.
[0045] This setting ensures that the clamping force is small in the early stage of loading and large in the later stage, and is positively correlated with the applied load. This effectively prevents excessive initial clamping force from causing crushing or thickness changes at the sample end, thus improving the authenticity and repeatability of compression test data.
[0046] 2) No wear-resistant plate 7 was installed.
[0047] In Example 2, the clamp is suitable for pressure loads of 10kN-50kN. In this example, as... Figure 5 As shown: Two clamping power components 3 that can be driven synchronously are used, and the height positions of the two clamping power components 3 are symmetrical about the effective test area. The clamping power components 3 can be hydraulic cylinders.
[0048] Example 3
[0049] This embodiment discloses a third type of composite material compression test fixture capable of simultaneous pressure application, such as... Figure 6 As shown, the difference between it and Embodiment 1 is that a clamping power component 3 is used, and the height position of the clamping power component 3 corresponds to the effective test area.
[0050] In Example 3, the clamp is suitable for pressure loads of 10kN or less.
[0051] In Embodiments 1 to 3, this application classifies the clamps into three models based on their applicable pressure load range. The first-level model is suitable for pressure loads below 10kN, the second-level model is suitable for pressure loads of 10kN-50kN, and the third-level model is suitable for pressure loads of 50-500kN. The structures of the three models are basically the same, mainly differing in size, as well as the selection and quantity of the clamping power component 3. The first-level model has a smaller applicable pressure load and provides a smaller clamping force, allowing for a smaller size and the use of only one clamping power component 3.
[0052] Different pressure load ranges are suitable for different test objects. For example, pressure loads below 10kN are suitable for testing unidirectional plates in the 90° direction or resin materials; pressure loads of 50-500kN are suitable for testing carbon fiber wind turbine blade pultruded plates in the 0° direction; and pressure loads of 10kN-50kN are suitable for situations in between. Especially in the compression performance tests related to wind turbine blades, the strength difference between different directions of the blade pultruded plates is very large. The 0° direction requires a larger load, while the 90° direction requires a smaller load. This application divides the fixture into three levels, allowing the selection of the corresponding model according to the test requirements, avoiding low accuracy and fixture damage caused by mismatch.
[0053] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
Claims
1. A composite material compression test fixture capable of synchronous pressure application, characterized in that: It includes a base frame and clamping blocks; the base frame includes a base plate that can be mounted on a test bench, a back plate connected to the base plate, and two side plates; two pairs of clamping blocks are arranged symmetrically vertically, and each pair of clamping blocks is arranged symmetrically horizontally; the two upper and lower clamping blocks on one side are slidably mounted on the same movable plate through a first vertical guide structure, and the side of the movable plate is slidably mounted on the back plate through a horizontal guide structure. A clamping power member is installed on the side of the movable plate away from the clamping blocks, and the clamping power member faces one side plate. The clamping power member is used to press against the side plate and push the clamping block on the side to clamp; the two upper and lower clamping blocks on the other side are slidably mounted on the same fixed plate through a second vertical guide structure, and the fixed plate is mounted on the other side plate; the end of the clamping block near the effective test area extends towards the effective test area to form an extension, and the non-clamping side of the extension has an arc-shaped chamfer.
2. The composite material compression test fixture capable of synchronous pressure application as described in claim 1, characterized in that: The radius of curvature of the curved chamfer is 10-30mm, the vertical width of the curved chamfer is 2mm-50mm, and the horizontal width of the curved chamfer is 1-10mm.
3. The composite material compression test fixture capable of synchronous pressure application as described in claim 1, characterized in that: The clamps are divided into three models according to the applicable pressure load range. The first model of the clamp can be used for pressure loads below 10kN, the second model of the clamp can be used for pressure loads of 10kN-50kN, and the third model of the clamp can be used for pressure loads of 50-500kN. The three models of the clamps have different sizes.
4. The composite material compression test fixture capable of synchronous pressure application as described in claim 3, characterized in that: For the first-gear model of the fixture, a single clamping power component is used, with its height position corresponding to the effective test area. For the second-gear and third-gear models of the fixture, two clamping power components that can be driven synchronously are used, with their height positions symmetrical about the effective test area.
5. The composite material compression test fixture capable of synchronous pressure application as described in any one of claims 1 to 4, characterized in that: The first vertical guide structure includes a vertical guide rail a on a movable plate and two vertical sliders a on one side of the upper and lower clamping blocks away from the clamping side, with the two vertical sliders a slidingly engaged on the vertical guide rail a simultaneously; the second vertical guide structure includes a vertical guide rail b on a fixed plate and two vertical sliders b on the other side of the upper and lower clamping blocks away from the clamping side, with the two vertical sliders b slidingly engaged on the vertical guide rail b simultaneously.
6. The composite material compression test fixture capable of synchronous pressure application as described in any one of claims 1 to 4, characterized in that: The lateral guide structure includes at least two lateral guide units distributed vertically. Each lateral guide unit includes a lateral guide rail on the back plate and a lateral slider on the side of the movable plate that slides with the lateral guide rail.
7. The composite material compression test fixture capable of synchronous pressure application as described in claim 6, characterized in that: The horizontal thickness of the movable plate is greater than that of the clamping block. The side of the movable plate where the horizontal slider is installed is thickened to allow the horizontal slider to be installed along its entire length.
8. The composite material compression test fixture capable of synchronous pressure application as described in any one of claims 1 to 4, characterized in that: The back plate is equipped with a limiting plate for limiting the side of the sample.
9. The composite material compression test fixture capable of synchronous pressure application as described in any one of claims 1 to 4, characterized in that: Wear-resistant plates can be replaced on the corresponding areas of the sample and the clamping blocks on both sides of the base plate.