Shearing resistance detection mechanism for ceramic matrix composite material

Abstract

The invention discloses a ceramic matrix composite material shear resistance detection mechanism, which comprises a base, the top of the base is provided with a placement cavity for placing a sample piece with a notch groove, the sample piece is attached to the inner wall of the placement cavity, and the notch groove and the top surface of the placement cavity are located on the same horizontal plane. The shearing block is used for applying horizontal shearing stress to one side of the notch groove of the sample piece under the action of vertical pressure. The device is simple and practical in structure, convenient to operate and capable of rapidly and conveniently detecting the shear resistance of the sample piece.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to a shear resistance detection mechanism for ceramic-based composite materials. Background Art

[0002] Ceramic-based composites are a new type of thermal structural / functional integrated material that combines the performance advantages of metal materials, ceramic materials and carbon materials. They have the characteristics of high temperature resistance, low density, high specific strength, high specific modulus, oxidation resistance, ablation resistance, corrosion resistance, insensitivity to cracks, and no catastrophic damage. They are widely used in aerospace, engine manufacturing, energy applications and other fields.

[0003] Currently, ceramic-based composite materials need to be tested for their shear resistance after molding, but existing testing mechanisms have problems such as complex structures and inconvenient operations. Summary of the invention

[0004] The purpose of the present invention is to provide a shear resistance testing mechanism for ceramic-based composite materials, which can simply and quickly test the alkali resistance of ceramic-based composite materials. The testing mechanism has a simple and practical structure and is easy to operate.

[0005] In order to solve the above technical problems, the present invention adopts the following solutions:

[0006] A mechanism for testing the shear resistance of ceramic-based composite materials comprises a base, wherein a placement cavity for placing a sample with a notch is provided on the top of the base, the sample is attached to the inner wall of the placement cavity, and the notch and the top surface of the placement cavity are in the same horizontal plane, and also comprises a shear block for applying horizontal shear stress to one side of the notch of the sample under the action of vertical pressure.

[0007] In this solution, a placement cavity is provided on the top of the base for accurately placing the specimen with a notch, which helps to locate and fix the specimen and ensure the consistency of the test conditions. The placement cavity is used to accommodate the specimen to ensure that the specimen is in the correct position and posture during the test. The inner wall of the placement cavity fits tightly with the specimen, which helps to eliminate lateral displacement during the test and improve the accuracy of the test. In addition, the top surface of the placement cavity is at the same level as the notch of the specimen, which ensures that the shear block can accurately act on one side of the notch when applying shear stress. The notch on the specimen is to simulate the shear stress that the material may encounter in actual application. The presence of the notch allows the shear stress to act more concentratedly on a specific area of ​​the specimen, thereby more accurately evaluating the shear resistance of the material. Under the action of vertical pressure, the shear block applies horizontal shear stress to one side of the notch of the specimen. The design of the shear block must ensure that it can stably apply shear stress while avoiding additional damage or deformation to the specimen. By accurately controlling the size of the vertical pressure and the movement trajectory of the shear block, accurate measurement of the shear resistance of the specimen can be achieved. First, the specimen is accurately placed in the placement cavity, and its notch is ensured to be at the same level as the top surface of the placement cavity. Then, a vertical pressure is applied to the shear block by some means (such as hydraulic or mechanical devices) so that it applies horizontal shear stress to one side of the notch of the specimen. During the test, the deformation, failure mode, and required shear stress of the specimen can be recorded to evaluate its shear resistance. The structure of the testing mechanism is simple and practical, and the operation is convenient. It can quickly and conveniently test the shear resistance of the specimen.

[0008] Optionally, the inner walls on both sides of the placement cavity are both inclined straight surfaces, the sample piece is tilted and fitted on one inclined straight surface, the shear block is movably arranged between the other inclined straight surface and the sample piece, the upper end of the placement cavity is open and the lower end is closed, and the upper end size is larger than the lower end size.

[0009] Optionally, the shear block is a trapezoidal wedge block adapted to the placement cavity, and both sides of the shear block are inclined surfaces adapted to the inclined straight surface.

[0010] Optionally, the height of the shear block is greater than the depth of the placement cavity and the length of the sample piece.

[0011] Optionally, it also includes a driving device for applying vertical force to the shear block, the driving device is a pressure testing machine, and the working end of the pressure testing machine applies vertical force to the shear block to squeeze the shear block and apply horizontal shear stress to one side of the notch.

[0012] Optionally, the pressure testing machine applies force at a speed of 50 N / s.

[0013] Optionally, the working end is a pressure head, the pressure head is located above the base, and the bottom surface of the pressure head is in flat contact with the top surface of the shear block.

[0014] Optionally, a limiting groove adapted to the pressure head is provided on the top surface of the base, the bottom surface of the limiting groove is connected to the placement cavity, the size of the limiting groove is larger than the size of the placement cavity, and a step is formed between the limiting groove and the placement cavity.

[0015] Optionally, the hardness and strength of the base and the shear block are greater than the hardness and strength of the sample.

[0016] Optionally, the front and rear sides of the placement cavity are both closed ends, and the front and rear side walls are inclined straight surfaces.

[0017] The present invention has the beneficial effects:

[0018] 1. In the present invention, the sample is first accurately placed in the placement cavity, and it is ensured that its notch is in the same horizontal plane as the top surface of the placement cavity. Then, vertical pressure is applied to the shear block to apply horizontal shear stress to one side of the notch of the sample. During the test, parameters such as deformation, failure mode and required shear stress of the sample can be recorded to evaluate its shear resistance. The structure of the detection mechanism is simple and practical, and the operation is convenient, and the shear resistance of the sample can be quickly and conveniently tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 Schematic diagram of the top view of the base;

[0021] Figure 3 is a schematic diagram of the three-dimensional structure of the shear block;

[0022] Figure 4 This is the plan structure diagram of the specimen.

[0023] Figure numerals: 1-base, 2-mounting cavity, 3-inclined straight surface, 4-shear block, 5-sample piece, 6-notch groove, 7-limiting groove, 8-pressure head, 9-pressure testing machine. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0025] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0026] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed", "opened", "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Example

[0028] A mechanism for testing the shear resistance of ceramic-based composite materials comprises a base 1, wherein a placement cavity 2 for placing a sample 5 with a notch 6 is provided on the top of the base 1, wherein the sample 5 is attached to the inner wall of the placement cavity 2, and the notch 6 and the top surface of the placement cavity 2 are in the same horizontal plane, and further comprises a shear block 4 for applying horizontal shear stress to one side of the notch 6 of the sample 5 under the action of vertical pressure.

[0029] In this embodiment, Figure 2 As shown, a placement cavity 2 is provided on the top of the base 1 for accurately placing the specimen 5 with the notch 6, which helps to locate and fix the specimen 5 and ensure the consistency of the test conditions. The placement cavity 2 is used to accommodate the specimen 5 to ensure that the specimen 5 is in the correct position and posture during the test. The inner wall of the placement cavity 2 fits tightly with the specimen 5, which helps to eliminate lateral displacement during the test and improve the accuracy of the test. In addition, the top surface of the placement cavity 2 and the notch 6 of the specimen 5 are on the same horizontal plane, which ensures that the shear block 4 can accurately act on one side of the notch 6 when applying shear stress. The notch 6 on the specimen 5 is to simulate the shear stress conditions that the material may encounter in actual applications, such as Figure 4As shown, the size of the specimen 5 is 30×15×5mm, and it is a rectangular plate. The notch 6 is parallel to the short side of the specimen 5, and the short side is the width of the specimen. The notch 6 does not completely penetrate the specimen, and the length of the notch 6 is half the width of the specimen 5. Notches 6 are provided on both long sides of the specimen 5, and the notches 6 on both sides are staggered up and down, so that the shear resistance of the upper and lower parts of the specimen 5 can be tested. The presence of the notch 6 allows the shear stress to act more concentratedly on a specific area of ​​the specimen 5, thereby more accurately evaluating the shear resistance of the material. Under the action of vertical pressure, the shear block 4 applies horizontal shear stress to one side of the notch 6 of the specimen 5. The one side of the notch 6 refers to the position along the short side of the specimen 5 that does not penetrate the specimen 5. The design of the shear block 4 must ensure that it can stably apply shear stress while avoiding additional damage or deformation to the specimen 5. By accurately controlling the size of the vertical pressure and the movement trajectory of the shear block 4, accurate measurement of the shear resistance of the specimen 5 can be achieved. Figure 1 As shown, first, the specimen 5 is accurately placed in the placement cavity 2, and its notch groove 6 is ensured to be at the same level as the top surface of the placement cavity 2. Then, a vertical pressure is applied to the shear block 4 in some way (such as a hydraulic or mechanical device) so that it applies a horizontal shear stress to one side of the notch groove 6 of the specimen 5. During the test, the deformation, failure mode, and required shear stress parameters of the specimen 5 can be recorded to evaluate its shear resistance. The structure of the detection mechanism is simple and practical, and the operation is convenient, and the shear resistance of the specimen 5 can be quickly and conveniently tested.

[0030] Furthermore, the inner walls on both sides of the placement cavity 2 are both inclined straight surfaces 3, the sample piece 5 is tilted and fitted on one inclined straight surface 3, the shear block 4 is movably arranged between the other inclined straight surface 3 and the sample piece 5, the placement cavity 2 is open at the upper end and closed at the lower end, and the upper end size is larger than the lower end size.

[0031] Specifically, Figure 1As shown, the inner walls of the two sides of the placement cavity 2 are designed to be inclined surfaces 3, which are helpful for positioning and fixing the sample 5. When the sample 5 is tilted and fitted on one side of the inclined surface 3, its other side naturally forms a certain angle with the other inclined surface 3. This angle helps the shear block 4 to distribute the force more evenly when applying shear stress. The design of the inclined surface 3 allows the sample 5 to remain stable during the test, avoiding test errors caused by the tilting or sliding of the sample 5. The shear block 4 is movably arranged between the other inclined surface 3 and the sample 5, which enables the shear block 4 to apply horizontal shear stress to one side of the notch 6 of the sample 5 under the action of vertical pressure. The placement cavity 2 is open at the upper end and closed at the lower end, and the upper end size is larger than the lower end size, which is helpful for placing and removing the sample 5 and ensures stability and accuracy during the test. The design of the upper end opening allows the sample 5 to be easily placed in and taken out of the placement cavity 2, while the closed lower end avoids the sample 5 from slipping or moving during the test.

[0032] Furthermore, the shear block 4 is a trapezoidal wedge block adapted to the placement cavity 2 , and both sides of the shear block 4 are inclined surfaces adapted to the inclined straight surface 3 .

[0033] Specifically, Figure 3 As shown, the design of the trapezoidal wedge enables the shear block 4 to distribute the force more evenly under the action of vertical pressure, thereby applying a stable and controllable horizontal shear stress to one side of the notch groove 6 of the specimen 5. The shape and size of the trapezoidal wedge need to be accurately matched with the shape and size of the placement cavity 2 and the specimen 5 to ensure the accuracy and reliability of the test. At the same time, the design of the trapezoidal wedge also helps to reduce the error caused by uneven force distribution during the test. The inclined surfaces on both sides of the shear block 4 fit closely with the inclined straight surface 3 of the placement cavity 2. This design helps to maintain the stability and accuracy of the specimen 5 during the test. The adaptability of the inclined surface also ensures that the shear block 4 can move along a predetermined path when the shear stress is applied, avoiding the test error caused by force deviation. The angle and size of the inclined surface need to be accurately calculated and designed according to the shape and size of the inclined straight surface 3 of the placement cavity 2 and the specimen 5. This adaptability design not only improves the accuracy of the test, but also helps to reduce friction and resistance during the test. During the test, the design of the trapezoidal wedge and the adaptability of the inclined surface together ensure the stability and accuracy of the specimen 5, help reduce the test error caused by the movement or tilt of the specimen 5, and improve the reliability and repeatability of the test.

[0034] Furthermore, the height of the shear block 4 is greater than the depth of the placement cavity 2 and the length of the sample 5 .

[0035] Specifically, the height of the shear block 4 is greater than the depth of the mounting cavity 2 and the length of the specimen 5, so that the shear block 4 can completely cover the notch 6 area of ​​the specimen 5 when the shear stress is applied, and extend to the outside of the mounting cavity 2. This design ensures that the shear stress can fully act on the notch 6 of the specimen 5, thereby more accurately evaluating its shear resistance.

[0036] Furthermore, it also includes a driving device for applying vertical force to the shear block 4, the driving device is a pressure testing machine 9, and the working end of the pressure testing machine 9 applies vertical force to the shear block 4 so that the shear block 4 and the base 1 are squeezed and horizontal shear stress is applied to one side of the notch groove 6.

[0037] Furthermore, the speed at which the pressure testing machine 9 applies force is 50 N / s.

[0038] Specifically, the speed at which the pressure testing machine 9 applies force can be adjusted on the machine. In this embodiment, the speed at which the force is applied is 50 N / s. The in-plane shear strength can be calculated by the formula S=Fm / Lh, where S is in-plane shear strength, in megapascals (MPa), Fm is maximum load, in Newtons (N), h is the thickness of the specimen 5, in millimeters (mm), and L is the gap distance, in millimeters (mm). The gap distance needs to be clearly defined.

[0039] Furthermore, the working end is a pressure head 8, which is located above the base 1, and the bottom surface of the pressure head 8 is in flat contact with the top surface of the shear block 4.

[0040] Furthermore, the top surface of the base 1 is provided with a limiting groove 7 adapted to the pressure head 8, the bottom surface of the limiting groove 7 is connected to the placement cavity 2, the size of the limiting groove 7 is larger than the size of the placement cavity 2, and a step is formed between the limiting groove 7 and the placement cavity 2.

[0041] Specifically, the bottom surface of the pressure head 8 and the top surface of the shear block 4 are in flat contact, which ensures that the shear block 4 can be evenly stressed when subjected to vertical pressure, and stably transfers the force to the sample 5, thereby realizing the shear stress on one side of the notch groove 6 of the sample 5. The design of flat surface contact reduces the problem of uneven force distribution caused by uneven contact area, and improves the accuracy and reliability of the test. The setting of the limit groove 7 ensures that the pressure head 8 can be stably moved and positioned during the test, avoiding the test error caused by the displacement or tilt of the pressure head 8. The bottom surface of the limit groove 7 is connected to the placement cavity 2, which is convenient for placing and removing the sample 5. The size of the limit groove 7 is larger than the size of the placement cavity 2, forming a stepped structure. This design not only provides enough space for the pressure head 8 to move, but also ensures that the pressure head 8 will not have unnecessary contact with the placement cavity 2 or the sample 5 during the test, thereby avoiding additional damage or deformation. The design of the pressure head 8 and the limit groove 7 together ensures the stability and accuracy of the test process. The pressure head 8 evenly transfers force to the shear block 4 through flat surface contact, while the limit groove 7 ensures the stable movement and positioning of the pressure head 8 during the test. This design helps to reduce errors and uncertainties during the test and improve the reliability and repeatability of the test.

[0042] Furthermore, the hardness and strength of the base 1 and the shear block 4 are greater than the hardness and strength of the sample 5 .

[0043] Specifically, since the base 1 and the shear block 4 need to withstand the vertical pressure from the pressure head 8 and convert it into shear stress on the specimen 5, their hardness and strength must be high enough to prevent deformation or damage during the test. The high hardness and high strength of the base 1 and the shear block 4 can ensure the stability and durability of the test equipment and reduce the test interruption and cost increase caused by equipment damage. When the hardness and strength of the base 1 and the shear block 4 are greater than that of the specimen 5, they can maintain the stability of shape and size during the test, thereby ensuring that the shear stress applied to the specimen 5 is accurate and controllable. This design helps to reduce the test error caused by the deformation of the test equipment and improve the accuracy and reliability of the test. Although the purpose of the test is to evaluate the shear resistance of the specimen 5, excessive damage may affect the accuracy of the test results. Therefore, the high hardness and high strength of the base 1 and the shear block 4 help to maintain the integrity of the specimen 5 during the test and prevent it from losing its representativeness due to excessive damage. By properly designing the hardness and strength of the base 1 and the shear block 4, the damage to the specimen 5 can be minimized while ensuring the accuracy of the test. The base 1 and the shear block 4 with high hardness and strength can respond to the vertical pressure of the pressure head 8 more quickly and convert it into shear stress on the specimen 5. This helps to shorten the test time and improve the test efficiency. This design makes the test process smoother and more efficient, and helps to reduce waiting time and resource waste during the test process.

[0044] Furthermore, the front and rear sides of the placement cavity 2 are both closed ends, and the front and rear side walls are inclined straight surfaces 3.

[0045] Specifically, Figure 2 As shown, the front and rear sides of the placement cavity 2 are closed ends, so that the sample 5 is completely surrounded in the placement cavity 2 during the test, avoiding interference from the external environment. The closed end design helps to ensure the accuracy and reliability of the test, because the sample 5 will not be affected by external factors (such as air flow, temperature changes, etc.) during the test. The front and rear side walls of the placement cavity 2 are inclined straight surfaces 3, so that the entire placement cavity 2 is in the shape of a square cone, and the shape and size of the shear block 4 are adapted to the shape and size of the placement cavity 2, so the shear block 4 is also in the shape of a square cone, so that the four inner walls of the placement cavity 2 are used to test the sample 5 in turn, avoiding deformation of the base 1 caused by long-term use of one side.

[0046] The method of using the present testing mechanism is as follows: first, a test piece 5 with two notches 6 is made, and then the test piece 5 is attached to an inclined surface 3 of the mounting cavity 2. At this time, the notch 6 is just flush with the top surface of the mounting cavity 2. Then the shear block 4 is placed between the test piece 5 and the opposite inclined surface 3. The pressure testing machine 9 is started, and the parameters of the pressure testing machine 9 are adjusted. The pressure testing force drives the pressure head 8 to squeeze the shear block 4 downward. The shear block 4 is in contact with the inner wall of the mounting cavity 2 and the side wall of the test piece 5 at the inclined surface 3. Therefore, the vertical force is decomposed into a force along the inclined surface and a horizontal force at the inclined surface of the shear block 4. The horizontal force is the shear stress on the test piece 5. As the pressure testing machine 9 continues to apply pressure until the test piece 5 is sheared off from the notch 6, the maximum load and end surface condition after shear fracture are recorded, and then the shear strength is calculated to determine whether it is qualified.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A ceramic matrix composite material shear resistance testing mechanism, comprising a base (1), characterized in that: The base (1) is provided with a placement cavity (2) on the top thereof for placing a sample (5) with a notch groove (6); the sample (5) is attached to the inner wall of the placement cavity (2), and the notch groove (6) and the top surface of the placement cavity (2) are in the same horizontal plane; and further comprises a shear block (4) for applying horizontal shear stress to one side of the notch groove (6) of the sample (5) under the action of vertical pressure.

2. A ceramic matrix composite material shear resistance testing mechanism according to claim 1, characterized in that: The inner walls on both sides of the placement cavity (2) are both inclined straight surfaces (3), the sample piece (5) is tilted and fitted on one of the inclined straight surfaces (3), the shear block (4) is movably arranged between the other inclined straight surface (3) and the sample piece (5), the placement cavity (2) is open at the upper end and closed at the lower end, and the size of the upper end is larger than that of the lower end.

3. A ceramic matrix composite material shear performance testing mechanism according to claim 2, characterized in that: The shear block (4) is a trapezoidal wedge block adapted to the placement cavity (2), and both sides of the shear block (4) are inclined surfaces adapted to the inclined straight surface (3).

4. A ceramic matrix composite material shear performance testing mechanism according to claim 3, characterized in that: The height of the shear block (4) is greater than the depth of the placement cavity (2) and the length of the sample piece (5).

5. A ceramic matrix composite material shear performance testing mechanism according to claim 1, characterized in that: It also includes a driving device for applying a vertical force to the shear block (4), the driving device being a pressure testing machine (9), the working end of the pressure testing machine (9) applying a vertical force to the shear block (4) so ​​that the shear block (4) and the base (1) are squeezed and a horizontal shear stress is applied to one side of the notch groove (6).

6. A ceramic matrix composite material shear performance testing mechanism according to claim 5, characterized in that: The speed at which the pressure testing machine (9) applies force is 50 N / s.

7. A ceramic matrix composite material shear performance testing mechanism according to claim 5, characterized in that: The working end is a pressure head (8), which is located above the base (1), and the bottom surface of the pressure head (8) is in flat contact with the top surface of the shear block (4).

8. A ceramic matrix composite material shear performance testing mechanism according to claim 7, characterized in that: The top surface of the base (1) is provided with a limiting groove (7) adapted to the pressure head (8); the bottom surface of the limiting groove (7) is connected to the placement cavity (2); the size of the limiting groove (7) is larger than the size of the placement cavity (2); and a step is formed between the limiting groove (7) and the placement cavity (2).

9. A ceramic matrix composite material shear performance testing mechanism according to claim 1, characterized in that: The hardness and strength of the base (1) and the shear block (4) are greater than the hardness and strength of the sample (5).

10. A ceramic matrix composite material shear performance testing mechanism according to claim 1, characterized in that: The front and rear sides of the placement cavity (2) are both closed ends, and the front and rear side walls are inclined straight surfaces (3).

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