Ceramic matrix composite T-shaped piece high-temperature test clamping device and method

Abstract

The invention discloses a ceramic matrix composite T-shaped piece high-temperature test clamping device and method, and belongs to the field of composite mechanical property test. The device adopts an up-down split type clamp design, and comprises an upper clamp, a lower clamp bottom plate and a lower clamp cover plate. The lower clamp bottom plate is provided with a test piece groove, sliding of the test piece is restrained through contact between the top end plane of the groove and the top end plane of the test piece, an unloading hole is formed in the right-angle position of the top end of the groove, machining stress concentration is eliminated, and lossless clamping of the fragile test piece is achieved. The upper and lower clamps are provided with water cooling channels to ensure high-temperature test safety. The problems that in a traditional method, a test piece is prone to slipping, and a clamping section is prone to being damaged are solved, the tedious process of pasting a reinforcing piece is avoided, the testing efficiency and the result accuracy are remarkably improved, and the method is suitable for testing the mechanical property of the aero-engine high-temperature component.

Description

Technical Field

[0001] This invention belongs to the field of mechanical property testing of composite materials, and particularly relates to a high-temperature testing clamping device and method for ceramic matrix composite T-shaped parts. Background Technology

[0002] As the heart of an aircraft, the aero-engine is a crucial indicator of a nation's scientific and technological strength and innovation capabilities. With continuous technological advancements, the performance of aero-engines is constantly improving. To meet the demands of high thrust-to-weight ratios and high-temperature environments, hot-end components of aero-engines, such as combustion chambers and turbines, must withstand temperatures ranging from 600°C to 1200°C and the interaction of complex stresses. Ceramic matrix composites (CMCs) possess the advantages of high temperature resistance and low density, making them ideal materials for these hot-end components.

[0003] T-shaped structures, as a typical local feature of CMC (Complex Metallic Control) hot-end components in aero-engines, are widely found in critical engine parts, such as turbine blades. During engine operation, these components are highly susceptible to failure due to the high temperatures and loads they endure. Therefore, conducting strength tests on T-shaped components and analyzing their strength performance is beneficial for their application in aero-engines. However, due to the brittleness of CMC, the clamping section is prone to failure during testing; furthermore, the loading method of the T-shaped component easily leads to slippage, resulting in inaccurate test data. Currently, there is no clamping device designed for T-shaped components that can achieve non-destructive clamping of the test piece and prevent slippage during testing. Therefore, designing a T-shaped component clamping device that does not damage the clamping section and prevents slippage during loading is a challenging problem. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature testing clamping device and method for ceramic matrix composite T-shaped parts, so as to overcome the shortcomings of the prior art.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-temperature testing clamping device for T-shaped ceramic matrix composite specimens includes an upper clamp, a lower clamp base plate, a lower clamp furnace inner cover plate, and a lower clamp furnace outer cover plate. The clamping device is used to clamp a T-shaped specimen composed of a vertical plate and a horizontal plate. One end of the horizontal plate is integrally connected to a non-end position of the vertical plate. The lower clamp base plate has a specimen groove for placing the vertical plate of the specimen. The top surface of the specimen groove is used to contact the top surface of the vertical plate of the specimen to constrain the sliding of the specimen. The lower clamp furnace inner cover plate and the lower clamp furnace outer cover plate are connected to the lower clamp base plate and press and fix the vertical plate of the specimen in the specimen groove. The lower end of the upper clamp has a load-applying surface for applying an upward load to the horizontal plate of the specimen.

[0007] Further improvements to optimize the technical solution include:

[0008] The two right angles at the top of the above-mentioned specimen groove are provided with openings at the top of the specimen groove to prevent the chamfer at the right angle from contacting the specimen.

[0009] The lower fixture base plate described above has a specimen observation port on its side, which is used to observe the loading status of the specimen.

[0010] The upper clamp and lower clamp base plates are respectively provided with upper clamp water cooling holes and lower clamp water cooling holes.

[0011] The water-cooling holes in the upper and lower clamps mentioned above are threaded holes.

[0012] The upper clamp described above has a width at the upper end that is smaller than the width at the lower end, and the lower end is provided with reinforcing ribs.

[0013] The width of the bottom plate of the lower clamp mentioned above is smaller in the middle than the width of its two ends.

[0014] The lower clamp base plate is provided with threaded holes. The lower clamp furnace inner cover plate and the lower clamp furnace outer cover plate are fixedly connected to the lower clamp base plate by screwing fastening bolts into the threaded holes.

[0015] A high-temperature testing method for ceramic matrix composite T-shaped parts, using the aforementioned high-temperature testing clamping device for ceramic matrix composite T-shaped parts, includes the following steps:

[0016] S1: Clamping the specimen: Place the specimen vertical plate in the specimen slot of the lower fixture base plate, ensuring that the top plane of the specimen vertical plate is in contact with the top plane of the specimen slot; then cover the specimen vertical plate with the lower fixture furnace inner cover plate and the lower fixture furnace outer cover plate, and use fastening bolts to connect and tighten them to the lower fixture base plate, thereby clamping and fixing the specimen.

[0017] S2: Install the clamps: Install the lower clamp portion of the clamped specimen onto the lower clamp of the testing machine via the lower clamp base plate; install the upper clamp onto the upper clamp of the testing machine;

[0018] S3: Centering adjustment: Adjust the position of the upper clamp using the testing machine so that the load-applying surface of the upper clamp is in full contact with and centered on the lower surface of the specimen's horizontal plate;

[0019] S4: Conduct the test: Start the high-temperature environment simulation device to heat the test area of ​​the specimen, and at the same time turn on the circulating cooling system. The cooling water circulates through the water cooling holes of the upper and lower clamps. After the temperature stabilizes, control the testing machine to apply an upward test load to the lower surface of the specimen through the upper clamp, and observe the specimen through the specimen observation port until the test is completed.

[0020] In step S1, the top right angle of the specimen is confirmed to be not in contact with the bottom plate of the lower fixture by the opening at the top of the specimen groove at the two right angles at the top of the specimen groove.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention effectively overcomes the problem of easy slippage of the specimen in traditional clamping methods by constraining the specimen by having the top plane of the specimen contact the top plane of the specimen groove, thus achieving non-destructive and non-slip clamping of brittle CMC specimens and fundamentally ensuring the accuracy and reliability of the test results.

[0023] 2. This invention opens a hole at the top right angle of the specimen groove, which completely eliminates the stress concentration point caused by the unavoidable chamfering during machining, and perfectly solves the industry problem that CMC materials are easily crushed and split in the clamping section, achieving true "non-destructive clamping".

[0024] 3. This invention eliminates the cumbersome step of pre-attaching reinforcing sheets to protect the specimens in traditional methods, avoiding the hours-long waiting time for pasting and curing, and reducing the experimental preparation time from hours to minutes, greatly improving testing efficiency.

[0025] 4. The present invention adopts a split fixture design, which is convenient for separate installation and alignment on the testing machine. It can detect and adjust the misalignment of the clamps in advance, and avoid abnormal damage to the specimens caused by poor alignment.

[0026] 5. The present invention has built-in upper and lower clamp water cooling holes, which can effectively block the heat of the high-temperature furnace from being conducted to the testing machine clamp, thus protecting the expensive testing equipment and ensuring that the clamp itself maintains its strength at high temperatures. It can be reused, improving the safety and service life of the device.

[0027] 6. This invention optimizes the structural shape of the upper clamp and the base plate of the lower clamp. The upper end of the upper clamp is designed to be narrower, while the bottom end is designed to be wider and has reinforcing ribs. The middle part of the lower clamp base plate is narrower. While ensuring structural strength and rigidity, it minimizes the required opening area of ​​the high-temperature furnace opening, reduces the special requirements on experimental equipment, and makes it more applicable.

[0028] 7. The present invention provides an observation port on the side of the lower fixture base plate to enable real-time in-situ observation of the test state of the specimen, which facilitates researchers to intuitively understand the experimental process and the failure mode of the specimen. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the present invention;

[0030] Figure 2This is a schematic diagram of the structure by which the inner cover plate of the lower fixture furnace and the outer cover plate of the lower fixture furnace fix the specimen to the bottom plate of the lower fixture;

[0031] Figure 3 This is a schematic diagram of the upper clamp;

[0032] Figure 4 This is a structural schematic diagram of the lower clamp base plate;

[0033] Figure 5 This is a schematic diagram of the structure of the lower fixture furnace inner cover plate;

[0034] Figure 6 This is a schematic diagram of the structure of the lower fixture furnace outer cover plate.

[0035] The attached diagram is labeled as follows: 1. Upper clamp; 2. Lower clamp base plate; 3. Lower clamp furnace inner cover plate; 4. Lower clamp furnace outer cover plate; 5. Specimen; 6. Fastening bolt; 7. Lower clamp water cooling hole; 8. Upper clamp water cooling hole; 9. Reinforcing rib; 10. Load application surface; 11. Specimen observation port; 12. Threaded hole; 13. Specimen groove; 14. Specimen groove top opening. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0037] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0038] Please see Figures 1 to 6 The present invention provides a high-temperature testing clamping device for ceramic matrix composite T-shaped parts, which mainly consists of an upper clamp 1, a lower clamp base plate 2, a lower clamp furnace inner cover plate 3, and a lower clamp furnace outer cover plate 4.

[0039] The lower clamp base plate 2 serves as the base of the entire device, used to support and position the specimen 5. A specimen groove 13, matching the dimensions of the vertical plate of the specimen 5, is located in the middle of the lower clamp base plate 2 for precise placement of the specimen 5. The top surface of the specimen groove 13 contacts the top surface of the vertical plate of the specimen 5, providing reverse support through surface contact, effectively preventing the specimen from sliding during loading. To eliminate stress concentration caused by the chamfers at the two right angles of the top edge during machining, two specimen groove top openings 14 are precisely machined at the two right angles of the top of the specimen groove 13. These specimen groove top openings 14 ensure that the fragile right-angled edges of the specimen 5 only contact a complete plane, without being subjected to any point or line compression, achieving non-destructive clamping. Furthermore, the width of the lower clamp base plate 2 is reduced in the middle to decrease the required opening area in the high-temperature furnace. A specimen observation port 11 is also provided on the side of the lower clamp base plate 2; this observation port is a through slot, allowing the experimenter to directly observe the deformation and damage of the specimen 5 during testing. The lower fixture base plate 2 is also machined with multiple threaded holes 12 for engaging with fastening bolts 6. The lower fixture base plate 2 also has a lower fixture water cooling hole 7 inside. In this embodiment, the water cooling hole is an M6 threaded hole, which can be used to connect a cooling water pipe joint to form a circulating water cooling channel to reduce the fixture temperature.

[0040] The inner cover plate 3 and outer cover plate 4 of the lower fixture furnace are connected to the threaded holes 12 on the bottom plate 2 of the lower fixture by fastening bolts 6, which firmly press and fix the vertical plate of the specimen 5 placed in the specimen slot 13. The two cover plates work together to ensure the stability and uniformity of the clamping.

[0041] The upper clamp 1 is used to apply load to the horizontal plate of the specimen 5. The upper end of the upper clamp 1 is narrower to further reduce the required opening area of ​​the high-temperature furnace; the lower end is wider and has reinforcing ribs 9 to significantly enhance its structural rigidity and strength under high-temperature loads and prevent deformation. The lower end of the upper clamp 1 is machined with a load-applying surface 10, which contacts the lower surface of the horizontal plate of the specimen 5 to apply an upward tensile load. The upper clamp 1 also has water-cooling holes 8 inside for connecting to a cooling system.

[0042] The working process and testing method of the device of the present invention are as follows:

[0043] S1: Specimen clamping: First, carefully place the vertical plate of the T-shaped specimen 5 made of CMC material into the specimen slot 13 of the lower fixture base plate 2. The operator should gently push the specimen to ensure that the top surface of its vertical plate is in complete contact with the top surface of the specimen slot 13. At this time, by observing the gap at the top opening 14 of the specimen slot, it can be confirmed that the right-angled edge of the specimen 5 is not in contact with the fixture, thus verifying that it is in a non-destructive clamping state. Then, cover the specimen 5 with the lower fixture furnace inner cover plate 3 and the lower fixture furnace outer cover plate 4, and use several M6 fastening bolts 6 to screw into the threaded holes 12 of the lower fixture base plate 2 through the cover plate, and tighten them with a torque wrench to the predetermined torque, thereby firmly and non-destructively clamping and fixing the specimen 5.

[0044] S2: Install the clamps: Install and fix the entire lower clamp portion, with the specimen 5 already clamped, onto the lower chuck of the high-temperature mechanical testing machine through both ends of the lower clamp base plate 2. Then, separately install and fix the upper clamp 1 onto the upper chuck of the testing machine.

[0045] S3: Centering adjustment: Start the testing machine and control the upper clamp to slowly descend, driving the upper clamp 1 to approach the horizontal plate of the specimen 5, so that the load application surface 10 at the lower end of the upper clamp 1 and the lower surface of the horizontal plate of the specimen 5 can make full and flat contact, and ensure that the load application direction is aligned with the axial direction of the vertical plate of the specimen to avoid generating additional bending moment.

[0046] S4: Testing: After centering, activate the high-temperature environment simulation device to heat the T-shaped feature area of ​​specimen 5 to the preset test temperature. Simultaneously, activate the circulating cooling system, channeling cooling water into the upper clamp water-cooling holes 8 and lower clamp water-cooling holes 7 to continuously circulate and remove heat, protecting the testing machine clamps and maintaining clamp performance. Once the temperature stabilizes, set the test parameters and control the testing machine to smoothly apply an upward tensile load to the horizontal plate of specimen 5 through the upper clamp 1. Throughout the test, the operator can observe the loading and failure process of specimen 5 in real time through the specimen observation port 11. The experiment is stopped when specimen 5 fails or the predetermined test procedure is completed.

[0047] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A high-temperature testing clamping device for T-shaped ceramic matrix composite parts, characterized in that, The device includes an upper clamp (1), a lower clamp base plate (2), a lower clamp furnace inner cover plate (3), and a lower clamp furnace outer cover plate (4). The clamping device is used to clamp a T-shaped specimen (5) composed of a vertical plate and a horizontal plate. One end of the horizontal plate is integrally connected to the non-end position of the vertical plate. The lower clamp base plate (2) is provided with a specimen groove (13) for placing the vertical plate of the specimen (5). The top surface of the specimen groove (13) is used to contact the top surface of the vertical plate of the specimen (5) to constrain the sliding of the specimen (5). The lower clamp furnace inner cover plate (3) and the lower clamp furnace outer cover plate (4) are connected to the lower clamp base plate (2) and press and fix the vertical plate of the specimen (5) in the specimen groove (13). The lower end of the upper clamp (1) is provided with a load-applying surface (10) for applying an upward load to the horizontal plate of the specimen (5).

2. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The specimen groove (13) is provided with two right angles at the top of the specimen groove (14) to prevent the chamfer at the right angle from contacting the specimen (5).

3. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The lower clamp base plate (2) has a specimen observation port (11) on its side, which is used to observe the loading status of the specimen (5).

4. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The upper clamp (1) and the lower clamp base plate (2) are respectively provided with upper clamp water cooling hole (8) and lower clamp water cooling hole (7).

5. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 4, characterized in that, The upper clamp water cooling hole (8) and the lower clamp water cooling hole (7) are threaded holes.

6. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The upper clamp (1) has a width at the upper end that is smaller than the width at the lower end, and a reinforcing rib (9) is provided at the lower end.

7. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The width of the middle part of the lower clamp base plate (2) is smaller than the width of its two ends.

8. The high-temperature testing clamping device for ceramic matrix composite T-shaped parts according to claim 1, characterized in that, The lower clamp base plate (2) is provided with threaded holes (12). The lower clamp furnace inner cover plate (3) and the lower clamp furnace outer cover plate (4) are fixedly connected to the lower clamp base plate (2) by screwing fastening bolts (6) into the threaded holes (12).

9. A high-temperature testing method for T-shaped ceramic matrix composite parts, characterized in that, The application of the high-temperature testing clamping device for ceramic matrix composite T-shaped parts as described in any one of claims 1-8 includes the following steps: S1: Clamping the specimen: Place the vertical plate of the specimen (5) in the specimen slot (13) of the lower fixture base plate (2), ensuring that the top plane of the vertical plate of the specimen (5) is in contact with the top plane of the specimen slot (13); then cover the vertical plate of the lower fixture furnace inner cover plate (3) and the lower fixture furnace outer cover plate (4) on the specimen (5), and use fastening bolts (6) to connect and tighten them to the lower fixture base plate (2) to clamp and fix the specimen (5); S2: Install the fixture: Install the lower fixture part of the clamped specimen (5) onto the lower clamp of the testing machine through the lower fixture base plate (2); install the upper fixture (1) onto the upper clamp of the testing machine; S3: Centering adjustment: Adjust the position of the upper clamp (1) using the testing machine so that the load application surface (10) of the upper clamp (1) is in full contact with and centered on the lower surface of the cross plate of the specimen (5); S4: Conduct the test: Start the high temperature environment simulation device to heat the test area of ​​the specimen (5), and at the same time turn on the circulating cooling system. The cooling water circulates through the water cooling hole (8) of the upper clamp and the water cooling hole (7) of the lower clamp. After the temperature stabilizes, control the testing machine to apply an upward test load to the lower surface of the cross plate of the specimen (5) through the upper clamp (1), and observe the specimen through the specimen observation port (11) until the test is completed.

10. The high-temperature testing method for a ceramic matrix composite T-shaped component according to claim 9, characterized in that, In step S1, the top right angle of the specimen (5) is confirmed to be not in contact with the bottom plate (2) of the lower fixture by means of the top opening (14) at the two right angles of the top of the specimen groove (13).

Images