Ceramic matrix composite T-shaped element high-temperature mechanical test clamp

Abstract

The invention provides a high-temperature mechanical test clamp for a T-shaped element made of a ceramic matrix composite material. The clamp comprises a clamp body and a pressing device, the clamp body is provided with a clamping cavity used for clamping and fixing the T-shaped element, and the pressing device is arranged in the clamping cavity and can provide stable pressing force for the high-temperature mechanical test of the ceramic matrix composite T-shaped element. The high-temperature mechanical test device for the T-shaped element made of the ceramic matrix composite material is divided into an upper part and a lower part, the upper part realizes friction clamping through a pressing device, and the lower part fixes the T-shaped element through the pressing device. According to the invention, the pressing force acting on the T-shaped element can be flexibly adjusted, and the corresponding tensile load is applied to the test piece under the condition that the test piece is not damaged.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature mechanical property evaluation of ceramic matrix composites, and particularly relates to a high-temperature mechanical test fixture for a T-shaped component of a ceramic matrix composite. Background Technique

[0002] When the key component of an aeroengine, the turbine guide vane, operates at high speed, it will bear loads such as centrifugal, aerodynamic, and thermal stresses. The complex cyclic alternating loads are extremely likely to cause fatigue failure of the turbine guide vane, resulting in engine failures and seriously affecting the normal operation of the engine and the flight safety of the aircraft. The T-shaped component is designed based on the dangerous part of the ceramic matrix turbine guide vane, the blade body - flange - T-shaped connection area, and can reflect the service conditions of the turbine guide vane under real working conditions in the test. Conducting high-temperature mechanical property tests on the T-shaped component is of great significance for improving the safety and performance of modern engines. With the continuous increase in the required thrust-to-weight ratio of aeroengines, the gas temperature at the turbine inlet has also increased accordingly. Compared with superalloys, ceramic matrix composites are ideal materials for advanced aeroengine hot-end components, with a much greater improvement in temperature resistance than superalloys and can stably operate at around 1600°C; at the same time, its density is about 2.2, only one-fourth of that of superalloys. The strong temperature resistance can effectively reduce the cooling air volume, and the low density can reduce the engine structure mass. These two advantages improve the engine thrust, reduce fuel consumption, and can reduce carbon emissions. To accelerate the application of ceramic matrix composites in aeroengine hot-end components to meet the research and development requirements of the new generation of aeroengines, it is necessary to conduct various strength and fatigue tests under high-temperature conditions to explore the high-temperature mechanical properties of ceramic matrix composite turbine guide vanes.

[0003] The service environment of turbine guide blades is extremely harsh, and they are subjected to complex alternating loads. The dangerous part of the turbine guide blade blade body-edge plate-T-type connection part has severe stress concentration and is prone to crack initiation, expansion and fracture, which eventually leads to fatigue failure of the turbine guide blade and causes aircraft engine failure. Therefore, it is very important to conduct high-temperature mechanical tests on the T-type connection part to explore its failure mechanism for predicting the service life of the turbine guide blade. However, due to the significant differences between composite materials and metal materials, such as the greater brittleness of ceramic-based composite materials compared to metal materials, the stiffness matching of the contact position between composite materials and metals, etc., the traditional high-temperature mechanical test fixtures for metal materials are no longer suitable for ceramic-based composite materials, and special high-temperature mechanical test fixtures need to be designed specifically for ceramic-based composite test pieces. There are few designs for high-temperature mechanical test fixtures for special structural elements such as T-type elements. Most of them are fixtures for straight plate-shaped elements. For example: Chinese patent application CN118777047 A discloses a fixture for high-temperature tensile and creep tests of ceramic-based composite Mini specimens, which has upper and lower clamping units that apply radial clamping forces to both ends of the specimen respectively, but this type of fixture is suitable for cross-sectional areas less than 1mm 2 Mini straight plate specimens are not suitable for T-shaped specimens with large cross-sectional areas. Chinese patent application CN118258983 A shows a ceramic matrix composite thermomechanical fatigue test system, which clamps the test piece by locking the upper and lower clamp heads and the upper and lower cover plates together. However, this clamping is limited by the shape of the test piece, requiring the test piece holding section to have a certain arc-shaped notch for clamping, and is only suitable for plates, not T-shaped test pieces. Summary of the invention

[0004] In order to overcome the shortcomings of existing fixtures and solve the above-mentioned technical problems, the present invention provides a high-temperature mechanical test fixture for T-type components of ceramic-based composite materials, which changes the way of applying loads, enhances the reliability of test results and the convenience of operation, and is suitable for high-temperature mechanical tests of T-type components of ceramic-based composite materials. The advantage of this fixture is that the clamping force can be flexibly adjusted to fix the T-type component, and a stable tensile load can be provided to the T-type component to ensure that the expected test effect can be achieved. That is, the present invention adopts an "upper compression, lower tightening" structure to load and fix the T-type component without destroying the T-type component. This clamping structure does not require the supporting section of the T-type component to have a certain arc-shaped notch, thereby avoiding the influence of external operations (such as processing arc-shaped notches) on the test.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A fixture for high-temperature mechanical tests of a ceramic matrix composite T-shaped component, comprising an upper fixture head, a lower fixture head, a compression bolt, upper and lower clamping blocks, and a cold water pipe; the upper fixture head and the lower fixture head are connected to a fatigue testing machine through the testing machine chuck; the compression bolt is connected to the upper fixture head and the lower fixture head through threads; the upper and lower clamping blocks are connected to the compression bolt through threads; the compression bolt and the upper and lower clamping blocks form a compression device to apply a load to the T-shaped component and prevent it from moving during the test, and the cold water pipe cools the upper fixture head and the lower fixture head to ensure its normal use; the upper fixture head and the lower fixture head are designed according to the geometric shape of the T-shaped component. The upper fixture head is designed in a "door" shape structure, which is convenient for the placement and clamping of the T-shaped component. The lower fixture head is designed in a "mouth" shape structure, which is convenient for the placement and compression of the T-shaped component.

[0007] Further, the compression bolt of the upper fixture head is connected to the side of the upper fixture head through threads; then the compression bolt of the upper fixture head is connected to the upper clamping block of the upper and lower clamping blocks through threads. The compression bolt of the upper fixture head and the upper clamping block together form an upper compression device. The T-shaped component contacts the upper compression device, and the compression bolt of the upper fixture head is rotated to apply pressure to the T-shaped component to achieve frictional clamping, and then a load can be applied to the T-shaped component through the fatigue testing machine.

[0008] Further, the compression bolt of the lower fixture head is connected to the bottom of the lower fixture head through threads; then the compression bolt of the lower fixture head is connected to the lower clamping block of the upper and lower clamping blocks through threads. The compression bolt of the lower fixture head and the lower clamping block together form a lower compression device. The T-shaped component contacts the lower compression device, and the compression bolt of the lower fixture head is rotated to apply pressure to the T-shaped component to firmly fix the T-shaped component on the inner wall of the chamber of the lower fixture head and prevent it from shaking during the test.

[0009] Further, each clamping block of the upper and lower clamping blocks of the upper and lower compression devices is provided with 4 compression bolts to facilitate the application of uniform compressive stress to the T-shaped component and avoid the influence of local stress concentration caused by clamping on the test results.

[0010] Beneficial effects:

[0011] The present invention uses 16 compression bolts for the fixation and tension of the T-shaped component, simplifies the operation steps, and adapts to T-shaped components of different thicknesses by adjusting the screwing distance of the compression bolt, that is, by adjusting the compression force and the clamping force, improving the versatility and applicability of the fixture. The lower fixture head of the fixture is provided with a groove to ensure the centering of the T-shaped component and avoid the influence on the test due to misalignment. Description of the drawings

[0012] Figure 1 It is a schematic diagram of the fixture for high-temperature mechanical tests of the ceramic matrix composite T-shaped component of the present invention;

[0013] Figure 2 Schematic diagram of a T-shaped component;

[0014] Figure 3 Schematic diagram of the upper fixture head;

[0015] Figure 4 Schematic diagram of the clamping block;

[0016] Figure 5 Schematic diagram of the lower fixture head;

[0017] Figure 6 Schematic diagram of the compression bolt

[0018] Figure 7 Schematic diagram of the cold water pipe;

[0019] Figure 8 Exploded view of the high-temperature mechanical test fixture for the ceramic matrix composite T-shaped component of the present invention.

[0020] Among them, the reference numerals are: upper fixture head 1, lower fixture head 2, compression bolt 3, upper and lower clamping blocks 4, T-shaped component 5, cold water pipe 6. Detailed implementation manners

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] The structure of a high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] The embodiment of the present invention adopts a T-shaped component manufactured by the SiC / SiC and two-dimensional braiding process, a fixture body and a compression device made of superalloy; a fatigue testing machine is used to apply a tensile load, and the range of the tensile load is 0-9 KN.

[0024] As Figure 1 , Figure 8As shown in the figure, the high-temperature mechanical test fixture for the ceramic matrix composite T-shaped component in the embodiment of the present invention includes an upper fixture head 1, a lower fixture head 2, a compression bolt 3, upper and lower clamping blocks 4, a T-shaped component 5, and a cold water pipe 6; the upper fixture head 1 and the lower fixture head 2 are connected to the fatigue testing machine through the testing machine chuck, the upper fixture head 1 and the lower fixture head 2 are connected to the cold water pipe 6 by welding, 8 threaded holes are opened on the upper fixture head 1 and the lower fixture head 2, and the compression bolt 3 is connected to the upper fixture head 1 and the lower fixture head 2 through the 8 threaded holes, and the upper and lower clamping blocks 4 are connected to the 8 compression bolts 3 through the threaded holes. The upper and lower clamping blocks 4 are closely attached to the T-shaped component 5 to facilitate the application of load and restraint. The lower fixture head 2 and the T-shaped component 5 are in close contact under the action of the compression bolt 3 and the upper and lower clamping blocks 4. The compression bolt 3 and the upper and lower clamping blocks 4 constitute a compression device that can apply load and restraint to the T-shaped component 5 to prevent it from moving during the test. The cold water pipe 6 can cool the upper and lower fixture heads to reduce the influence of high temperature on the fixture.

[0025] The upper fixture head 1 and the lower fixture head 2 are designed according to the geometric shape of the T-shaped component 5. The upper fixture head 1 is designed in a "door" shape structure, which is convenient for the placement and clamping of the T-shaped component 5. A cold water pipe 6 is provided above the upper fixture head 1, and 8 threaded holes are opened below for connecting the compression bolt 3 and the upper and lower clamping blocks 4. The lower fixture head 2 is designed in a "mouth" shape structure, which is convenient for the placement and compression of the T-shaped component 5. 2 cold water pipes 6 are provided at the bottom of the lower fixture head 2, and 8 threaded holes are also opened at the bottom for connecting the compression bolt 3 and the upper and lower clamping blocks 4. In addition, 2 grooves are opened above the lower fixture head 2, and the sizes of the 2 grooves are basically the same as the size of the T-shaped component 5, which is convenient for ensuring the centering of the T-shaped component 5 when the compression bolt 3 is tightened, and ensuring the accuracy and reliability of the test results. During the high-temperature mechanical test, the fixture is cooled through the cold water pipe 6 to ensure the normal use of the fixture.

[0026] In this embodiment, an upper compression and lower tightening structure is adopted. Specifically, the upper compression is realized through the compression device. The compression device is composed of the compression bolt 3 and the upper and lower clamping blocks 4. The compression bolt 3 is connected to the upper fixture head 1 and the lower fixture head 2 through threads, and the upper and lower clamping blocks 4 are connected to the compression bolt 3 through threads; the compression device composed of the compression bolt 3 and the upper and lower clamping blocks 4 can apply load to the T-shaped component 5 and prevent it from moving during the test. Sufficient friction is provided to the T-shaped component 5 through the compression structure, and then a tensile load is provided to the T-shaped component 5 through the fatigue testing machine. The lower tightening structure can make the T-shaped component 5 in close contact with the groove in the lower fixture head 2, and the compression force is changed by continuously adjusting the compression device until the T-shaped component 5 does not move.

[0027] The specific functions of each part are introduced in detail below with reference to the drawings. Figure 2 It is a schematic diagram of the T-shaped component 5, which is the clamping and test object of this fixture. Figure 3It is a schematic diagram of the upper fixture head 1. The main function of the upper fixture head 1 is to transmit the tensile force of the fatigue testing machine. The tensile force of the fatigue testing machine acts on the upper fixture head 1, and then the upper fixture head 1 transmits the tensile force to the T-shaped element 5 through the compression bolts 3 and the upper and lower clamping blocks 4 connected thereto. And there is a cold water pipe 6 above the upper fixture head 1, which can cool the upper fixture head 1 during the high-temperature test. Figure 4 It is a schematic diagram of the upper and lower clamping blocks 4. The main function of the upper and lower clamping blocks 4 is to jointly form a compression device with the compression bolts 3 to apply a tensile force to the T-shaped element 5. There are 4 threaded holes at the rear of the upper and lower clamping blocks 4, which are convenient for connecting with the compression bolts 3. Figure 5 It is a schematic diagram of the lower fixture head 2. The main function of the lower fixture head 2 is to jointly form a compression device with the compression bolts 3 to apply a restraint to the T-shaped element 5 to ensure that the T-shaped element 5 does not move during the test. There are 2 cold water pipes 6 at the bottom of the lower fixture head 2, which are convenient for uniformly cooling the lower fixture head 2 during the test. Figure 6 It is a schematic diagram of the compression bolt 3. The main function of the compression bolt 3 is to jointly form a compression device with the upper and lower clamping blocks 4 to provide tensile force and restraint for the T-shaped element. In this fixture, there are 16 compression bolts 3 in total, 8 for each of the upper fixture head 1 and the lower fixture head 2, which can provide uniform tensile force and restraint and will not affect the test results due to local stress concentration. Figure 7 It is a schematic diagram of the cold water pipe 6. The main function of the cold water pipe 6 is to cool the upper fixture head 1 and the lower fixture head 2 to ensure their normal use at high temperatures.

[0028] The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention shall be covered within the scope of the present invention.

Claims

1. A high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component, characterized in that, It includes an upper fixture head (1), a lower fixture head (2), a compression bolt (3), upper and lower clamping blocks (4), and a cold water pipe (6); the upper fixture head (1) and the lower fixture head (2) are connected to the fatigue testing machine through the testing machine chuck; the compression bolt (3) is connected to the upper fixture head (1) and the lower fixture head (2) by threads; the upper and lower clamping blocks (4) are connected to the compression bolt by threads; the compression bolt (3) and the upper and lower clamping blocks (4) form a compression device to apply a load to the T-shaped element (5) and prevent it from moving during the test, and the cold water pipe (6) cools the upper fixture head (1) and the lower fixture head (2) to ensure their normal use; the upper fixture head (1) and the lower fixture head (2) are designed according to the geometric shape of the T-shaped element (5), the upper fixture head (1) is designed in a "door" shape structure to facilitate the insertion and clamping of the T-shaped element (5), and the lower fixture head (2) is designed in a "mouth" shape structure to facilitate the insertion and compression of the T-shaped element (5).

2. The high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, wherein: The compression bolt (3) and the upper and lower clamping blocks (4) form a compression device; the compression device applies pressure to the T-shaped element (5) by rotating the compression bolt (3).

3. A high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 2, characterized in that: In the compression device, the compression bolt (3) is connected to the upper fixture head (1) and the lower fixture head (2) through threaded holes, and different compression forces can be flexibly provided for the T-shaped element (5) by adjusting the compression bolt (3).

4. The high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: In the fixture, the transmission route of the compression force is: the compression bolt (3) generates a horizontal compression force through the threads connected to the upper fixture head (1) and the lower fixture head (2) and transmits it to the upper and lower clamping blocks (4), and the upper and lower clamping blocks (4) transmit it to the T-shaped element (5) through contact to form a compression force.

5. A high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: The upper and lower clamping blocks (4) are connected to 4 compression bolts (3) by threads to ensure uniform compression of the T-shaped element (5) and prevent the test from being affected by uneven pressure distribution of the compression device.

6. The high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: Two clamping blocks are provided on the lower fixture head (2) to prevent the T-shaped element (5) from moving during the test, thus ensuring the reliability of the test results.

7. A high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: Cold water pipes (6) are provided on both the upper fixture head (1) and the lower fixture head (2) for cooling the upper fixture head (1) and the lower fixture head (2).

8. The high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: A cold water pipe (6) is provided above the upper fixture head (1), and 8 threaded holes are opened below for connecting the compression bolt (3) and the upper and lower clamping blocks (4).

9. The high-temperature mechanical test fixture for the ceramic matrix composite T-shaped component according to claim 1, characterized in that: Two cold water pipes (6) are provided at the bottom of the lower fixture head (2), and 8 threaded holes are also opened at the bottom for connecting the compression bolt (3) and the upper and lower clamping blocks (4).

10. A high-temperature mechanical test fixture for a ceramic matrix composite T-shaped component according to claim 1, characterized in that: Two grooves are opened above the lower fixture head (2), and the sizes of the two grooves are the same as the size of the T-shaped element (5) to facilitate centering of the T-shaped element (5) when the compression bolt (3) is tightened.

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