High-temperature bending test clamp for T-shaped element made of ceramic matrix composite material

Abstract

The invention relates to a high-temperature bending test clamp for a T-shaped element made of a ceramic matrix composite material. The fixture comprises a fixture body, a pressing device and a cooling device, the high-temperature bending test device for the T-shaped element made of the ceramic matrix composite material is divided into an upper part and a lower part, one side of the T-shaped element is fixed by the upper half part through the pressing device, and then a pressure load is applied to the T-shaped element through an upper pressure head pin. The lower half part mainly plays a fixing role, and the other side of the T-shaped element is fixed through the lower clamp and the fixing bolt. According to the invention, the pressing force acting on the T-shaped element can be flexibly adjusted, and a pressure load perpendicular to the element is applied to the T-shaped element under the condition that a test piece is not damaged, so that bending loading is realized.

Description

Technical Field

[0001] The invention belongs to the field of high-temperature bending performance evaluation of ceramic-based composite materials, and in particular relates to a high-temperature bending test fixture for a T-shaped element of a ceramic-based composite material. Background Art

[0002] Turbine guide vanes, a key component of aircraft engines, are subjected to centrifugal, aerodynamic, and thermal stresses during high-speed operation. Complex cyclic loading can easily cause fatigue failure in turbine guide vanes, leading to engine failure and seriously impacting engine operation and aircraft safety. T-shaped elements are designed based on the T-shaped connection area between the blade and the blade edge, a critical area of the blade. These elements can demonstrate the service life of turbine guide vanes under real-world operating conditions. High-temperature bending performance testing of T-shaped elements can help assess damage to turbine guide vanes during actual service, facilitating regular maintenance and preventing engine accidents. As the thrust-to-weight ratio requirements of aircraft engines increase, turbine inlet gas temperatures continue to rise. Compared to high-temperature alloys, ceramic matrix composites (CMCs), due to their high-temperature resistance and lightweight properties, are ideal materials for advanced aircraft engine hot-end components. They can withstand temperatures reaching approximately 1600°C, far exceeding those of high-temperature alloys, while possessing a density of only approximately 2.2, one-quarter that of high-temperature alloys. This material's high temperature resistance significantly reduces cooling air volume, while its low density helps reduce engine structural weight, thereby increasing thrust, reducing fuel consumption, and lowering carbon emissions. In order to accelerate the application of ceramic-based composites in the hot end components of aircraft engines and adapt to the development needs of the new generation of aircraft engines, it is necessary to conduct in-depth research on their strength and fatigue properties under high temperature conditions, especially to conduct systematic tests on the high-temperature bending performance of turbine guide blades.

[0003] Turbine guide blades operate in extremely harsh environments, subjecting them to complex alternating loads. The T-junction, a critical area between the blade and the blade edge, can bend due to the impact of the combustion gas. This stress concentration is highly susceptible to crack initiation, propagation, and fracture, ultimately leading to fatigue failure of the turbine guide blade and aircraft engine failure. Therefore, conducting high-temperature bending tests on the T-junction and investigating its failure mechanism is crucial for predicting the service life of turbine guide blades. Few high-temperature bending test fixtures have been designed for this specialized structural element, T-shaped components. Most are tensile fixtures designed for straight plate-shaped components. For example, Chinese patent application CN118483033 A discloses a high-temperature tensile testing fixture and method for ceramic-based composite materials with adaptive centering. The fixture comprises two sets of identical fixture units, which securely clamp the straight plate specimen using two wedge-shaped blocks that fit together to form a wedge-shaped groove. However, this fixture can only perform tensile testing of straight plate-shaped components at high temperatures and cannot perform high-temperature bending testing of T-shaped components. Chinese patent CN221572058 U shows a high-temperature tensile test fixture for ceramic-based composite fiber bundles. The device clamps the test piece through a tapered groove in the mounting groove of the chuck. However, this clamping method is limited by the shape of the test piece and requires a certain arc-shaped notch in the holding section of the test piece for clamping. Moreover, it is only applicable to plates and can only perform tensile tests at high temperatures. It is not suitable for high-temperature bending tests of T-type components. Summary of the Invention

[0004] In order to overcome the shortcomings of existing fixtures, the present invention provides a high-temperature bending test fixture for T-shaped components of ceramic-based composite materials, which changes the way of fixing and applying loads, enhances the reliability of test results and the convenience of operation, and is suitable for high-temperature bending tests of T-shaped components of ceramic-based composite materials. The advantage of the fixture of the present invention is that it achieves the bending of T-shaped components at high temperatures by changing the form of applied force and the direction of the force acting on the T-shaped component. The present invention has strong adaptability to T-shaped components, can clamp components of different thicknesses, and can provide a stable pressure load to the T-shaped component, ensuring that the expected test effect can be achieved.

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

[0006] A high-temperature bending test fixture for a ceramic-based composite T-shaped element, comprising a fixture head, a water-cooled connecting rod, a back plate, an upper fixture, an upper pressure head, an upper pressure head pin, a lower fixture, and fixing bolts; the entire fixture is connected to a testing machine via the fixture head; the fixture head is connected to the water-cooled connecting rod via a thread; the water-cooled connecting rod is connected to the upper pressure head via a thread, the upper pressure head pin is placed in an opening of the upper pressure head, the upper pressure head pin and the T-shaped element are in contact with each other, the upper fixture and the lower fixture are connected to the back plate via fixing bolts, the T-shaped element is located between the upper fixture, the lower fixture, and the back plate, the upper fixture, the lower fixture, the back plate, and the fixing bolts together constitute a clamping device, the clamping force applied to the T-shaped element is adjusted by adjusting the fixing bolts, cooling water is passed into the water-cooled connecting rod to cool the fixture to ensure its normal use.

[0007] Furthermore, the upper fixture, the lower fixture and the back plate are designed to be split.

[0008] Furthermore, the applicability of the clamp is improved by adjusting the screw-in length of the fixing bolt to adapt to T-shaped elements of different thicknesses.

[0009] Furthermore, it is applicable to T-shaped elements of different thicknesses to prevent them from shaking during the test.

[0010] Furthermore, the clamping device is provided with 6 fixing bolts so as to apply uniform compressive stress to the T-shaped element, thereby avoiding the influence of local stress concentration caused by clamping and fixing on the test results.

[0011] Furthermore, the upper top surface of the lower clamp is designed to be an arc surface.

[0012] Furthermore, the clamp heads are two, one upper and one lower.

[0013] Furthermore, the water-cooling connecting rods are two, one above the other.

[0014] Furthermore, the lower clamp 8 is used to clamp and fix the lower half of the T-shaped element 7 .

[0015] Furthermore, the upper clamp 4 is used to clamp and fix the upper half of the T-shaped element 7 .

[0016] Beneficial effects:

[0017] The present invention overcomes the current situation that the existing fixture cannot complete the high-temperature bending test of the T-shaped element. The bending of the T-shaped element is achieved by fixing the clamping device and applying a pressure load with the upper pressure head, which changes the way of applying the load and has strong operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a high-temperature bending test fixture for a ceramic matrix composite T-shaped element of the present invention;

[0019] Figure 2 It is a schematic diagram of a T-type element;

[0020] Figure 3 Schematic diagram of the fixture head;

[0021] Figure 4 Schematic diagram of water cooling connecting rod;

[0022] Figure 5 For the purpose of pressing the head upwards;

[0023] Figure 6 Schematic diagram of the lower fixture;

[0024] Figure 7 Schematic diagram of the upper fixture;

[0025] Figure 8 Schematic diagram of the back panel;

[0026] Figure 9 Schematic diagram of the upper pressure head pin;

[0027] Figure 10 Schematic diagram of the fixing bolts.

[0028] Among them, the accompanying drawings are marked as: clamp head 1, water-cooling connecting rod 2, back plate 3, upper clamp 4, upper pressure head 5, upper pressure head pin 6, T-shaped element 7, lower clamp 8, and fixing bolt 9. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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 intended 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. The structure of a high-temperature bending test fixture for T-type components of ceramic-based composite materials of the present invention is described in detail below in conjunction with the accompanying drawings.

[0030] The embodiment of the present invention adopts SiC / SiC, a T-shaped element manufactured by a two-dimensional weaving process, and a clamp body and a clamping device manufactured by a high-temperature alloy; and adopts a fatigue testing machine to apply a tensile load.

[0031] like Figures 1-10As shown, the high-temperature bending test fixture of the ceramic-based composite T-shaped element of the embodiment of the present invention includes a fixture head 1, a water-cooled connecting rod 2, a back plate 3, an upper fixture 4, an upper pressure head 5, an upper pressure head pin 6, a lower fixture 8, and a fixing bolt 9; the entire fixture is connected to the testing machine through the fixture head 1; the fixture head 1 is connected to the water-cooled connecting rod 2 by a thread, and the water-cooled connecting rod 2 is connected to the upper pressure head 5 by a thread, the upper pressure head 5 has a hole for inserting the upper pressure head pin 6, and the upper pressure head pin 6 is in contact with the T-shaped element 7. The upper fixture 4 and the lower fixture 8 are connected to the back plate 3 by the fixing bolt 9. The T-shaped element 7 is located between the upper fixture 4, the lower fixture 8 and the back plate 3. The upper fixture 4, the lower fixture 8, the back plate 3 and the fixing bolt 9 together constitute a clamping device. The clamping force applied to the T-shaped element 7 can be adjusted by adjusting the fixing bolt 9. The clamping device is mainly used to prevent the T-shaped element 7 from moving during the test. The water-cooled connecting rod 2 can pass cooling water to cool the fixture to ensure its normal use.

[0032] The detailed installation steps of the ceramic matrix composite material T-shaped element high temperature bending test fixture of the present invention are as follows:

[0033] Based on the geometry of the T-shaped element 7 and its deformation during the high-temperature bending test, the upper and lower fixtures 4 and 8 are designed so that after the T-shaped element is placed in the grooves of the upper and lower fixtures 4 and 8, the T-shaped element 7 can be fixed to the backplate 3 by adjusting the fixing bolts 9. During the high-temperature bending test, the T-shaped element 7 will not come into contact with the lower fixture 8 and affect the test. The compressive load on the T-shaped element 7 is applied by the fatigue testing machine to the upper ram 5 and through the upper ram pin 6. The water-cooled connecting rod 2 cools the fixture to prevent damage due to excessive temperatures.

[0034] like Figure 2 As shown, the embodiment of the present invention utilizes an upper and lower clamping structure that secures the test piece without damaging it. This structure does not affect the test results and offers flexible adjustment and strong adaptability to the test piece. By adjusting the fixing bolts 9, the pressure acting on the T-shaped element 7 can be adjusted to achieve securement.

[0035] Preferably, a protrusion is provided on the back of the back plate 3 of the present invention, which acts as a reinforcing rib to prevent the back plate 3 from bending during the high-temperature bending test.

[0036] Preferably, the fixture of the present invention is characterized in that an arc-shaped surface is provided on the upper surface of the lower fixture 8 to prevent the T-shaped element 7 from contacting it during the high-temperature bending test and affecting the test.

[0037] Preferably, the volume of the upper clamp 4 is smaller than that of the lower clamp 8. This is because during the high-temperature bending test, the pressure on the lower clamp 8 is greater than the pressure on the upper clamp 8. Therefore, the lower clamp 8 needs to have a certain mass and cooperate with the clamping device to fix the T-shaped element 7.

[0038] Figure 3 Shown is a schematic diagram of the fixture head 1. The high-temperature bending test fixture for the T-shaped component 7 of the present invention includes two fixture heads 1 (one each at the upper and lower ends). The entire fixture is connected to the fatigue testing machine via the two fixture heads 1 to ensure the application of the load. Figure 4 What is shown is a schematic diagram of a water-cooled connecting rod 2. The high-temperature bending test fixture for the T-shaped element 7 of the present invention includes two water-cooled connecting rods 2 (one each on the upper and lower sides). The function of the water-cooled connecting rod 2 is to cool the fixture during the test to ensure that the fixture can be used normally. Figure 5 What is shown is a schematic diagram of the upper pressure head 5. The function of the upper pressure head 5 is mainly to convert the pressure of the fatigue testing machine into the bending pressure of the T-shaped element 7, playing the role of force transmission and conversion. Figure 6 What is shown is a schematic diagram of the lower clamp 8 , which mainly functions to clamp and fix the lower half of the T-shaped element 7 in coordination with other parts of the clamp. Figure 7 What is shown is a schematic diagram of the upper clamp 4 , which mainly functions to cooperate with other parts of the clamp to clamp and fix the upper half of the T-shaped element 7 . Figure 8 The diagram shows a schematic diagram of back plate 3, which primarily functions in conjunction with upper clamp 4, lower clamp 8, and fixing bolts 9 to secure T-shaped element 7. A raised rib on the rear of back plate 3 acts as a reinforcing rib to prevent bending during the high-temperature bending test of T-shaped element 7. Figure 9 What is shown is a schematic diagram of the upper pressure head pin 6. The upper pressure head pin 6 mainly plays the role of pressure transmission, applying the pressure of the upper pressure head to the T-shaped element 7 to achieve bending loading of the T-shaped element 7. Figure 10 What is shown is a schematic diagram of the fixing bolt 9 , the main function of the fixing bolt 9 is to cooperate with the upper clamp 4 , the lower clamp 8 and the back plate 3 to achieve the fixation of the T-shaped element 7 .

[0039] The above embodiments are provided for the purpose of describing the present invention only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the present invention are intended to be within the scope of the present invention.

Claims

1. A high temperature bending test fixture for ceramic matrix composite T-shaped components, characterized in that: It includes a fixture head, a water-cooled connecting rod, a back plate, an upper fixture, an upper pressure head, an upper pressure head pin, a lower fixture, and a fixing bolt; the entire fixture is connected to the testing machine through the fixture head; the fixture head is connected to the water-cooled connecting rod through a thread; the water-cooled connecting rod is connected to the upper pressure head through a thread, the upper pressure head pin is placed in the opening of the upper pressure head, the upper pressure head pin and the T-shaped element are in contact with each other, the upper fixture and the lower fixture are connected to the back plate through fixing bolts, the T-shaped element is located in the middle of the upper fixture, the lower fixture, the back plate and the fixing bolts together form a clamping device, and the clamping force applied to the T-shaped element is adjusted by adjusting the fixing bolts, and cooling water is passed into the water-cooled connecting rod to cool the fixture to ensure its normal use.

2. A ceramic matrix composite T-shaped component high temperature bending test fixture according to claim 1, characterized in that: The upper clamp, lower clamp and back plate adopt a split design.

3. A high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 2, characterized in that: By adjusting the screw-in length of the fixing bolt, the clamp can be adapted to T-shaped components of different thicknesses, thereby improving the applicability of the clamp.

4. A ceramic matrix composite T-shaped component high temperature bending test fixture according to claim 1, characterized in that: Applicable to T-shaped components of different thicknesses to prevent them from shaking during testing.

5. A high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 4, characterized in that: The clamping device is provided with 6 fixing bolts to apply uniform compressive stress to the T-shaped element, so as to avoid the influence of local stress concentration caused by clamping and fixing on the test results.

6. A high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 4, characterized in that: The upper top surface of the lower fixture is designed to be an arc surface.

7. The high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 1, characterized in that: The clamp heads are divided into two, upper and lower ones.

8. The high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 1, characterized in that: The water-cooling connecting rods are two, upper and lower.

9. The high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 1, characterized in that: The lower clamp is used to clamp and fix the lower half of the T-shaped element.

10. The high temperature bending test fixture for ceramic matrix composite T-shaped components according to claim 1, characterized in that: The upper clamp is used to clamp and fix the upper half of the T-shaped element.

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