Self-adaptive ceramic matrix composite tensile test fixture and method

Abstract

The invention provides a self-adaptive tensile test fixture and method for a ceramic matrix composite material, and relates to the technical field of mechanical test of composite materials. The clamp comprises two clamping heads which are oppositely arranged, a clamping block is installed at the inner end of each clamping head, side clamping blocks which can slide and rotate are arranged on the clamping blocks, and the side clamping blocks are inserted into U-shaped grooves of the clamping blocks through connecting sections and locked by bolts. The clamping blocks can slide on the chuck guide rails to adapt to samples with different thicknesses, the side clamping blocks can be attached to the side faces of the samples with different shapes in a self-adaptive mode, and four-side clamping and automatic centering are achieved. According to the structure, eccentric loading is effectively avoided, the clamping stability and the testing precision are improved, and the device is suitable for tensile property testing of multi-specification ceramic matrix composites.

Description

Technical Field

[0001] This invention belongs to the field of composite material mechanics, specifically relating to an adaptive ceramic matrix composite tensile testing fixture and method. Background Technology

[0002] Composite materials are widely used in the aerospace industry due to their high specific strength, specific stiffness, and fatigue resistance, and their usage ratio determines the lightweight nature and main performance of structures. However, composite materials are subjected to various loads during service, such as tension, bending, and impact, as well as the coupling of various loads. To evaluate the strength of composite materials, it is essential to first explore their fundamental mechanical properties. Tensile strength is one of the most fundamental mechanical properties of composite materials, and tensile testing is the core method for testing the tensile properties of composite materials. Therefore, using tensile testing to determine the tensile strength of composite materials is particularly important.

[0003] When conducting tensile tests on composite materials, the test results are affected by various factors, leading to varying degrees of deviation. While existing research and standards for composite material tensile testing, such as ASTM D3039 and GJB 8736-2015, assume ideal experimental conditions, actual testing can be subject to different errors due to variations in operator skill. Common errors include clamping errors and off-axis loads, which significantly impact the accuracy of composite material tensile test results. Therefore, to more accurately test and analyze the tensile properties of composite materials, there is an urgent need to design a clamping tool that can adapt to operational errors.

[0004] Currently, some existing test fixtures can automatically correct for off-axis loads. However, due to variations in specimen size, a single fixture can only be used for a batch of specimens, and testing different specimens will result in off-axis loads and clamping errors. Therefore, the existing tooling designs have limited applicability, and special fixtures often need to be designed for specimens of different sizes. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adaptive ceramic matrix composite tensile testing fixture to solve the problems of existing testing devices where the applied stress deviates and it is difficult to adapt to specimens of different sizes and shapes.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An adaptive ceramic matrix composite tensile testing fixture, comprising: Two chucks are arranged opposite each other, and two oppositely arranged clamping blocks are installed on the inner end of each chuck. Each clamping block is provided with two oppositely arranged side clamping blocks. The center planes of the two side clamping blocks, the center planes of the two clamping blocks, and the center planes of the two chucks are perpendicular to each other. Each of the side clamps is provided with connecting sections on both sides, and the clamps are provided with U-shaped grooves for the connecting sections to be inserted into, and the connecting sections can slide and rotate within the U-shaped grooves; The side wall of the clamping block has a through hole that communicates with the U-shaped groove, and a bolt for locking the position of the side clamping block is provided in the through hole.

[0007] A further improvement of the present invention is that: Preferably, each of the clamps includes an integrally connected force-applying section and a clamping section, the inner end face of the clamping section is provided with a sliding groove, and the clamping block is provided with a slider that cooperates with the sliding groove.

[0008] Preferably, the slider and the groove form a dovetail fit structure.

[0009] Preferably, the clamping block includes an integrally connected boss structure and a support plate. The inner end face of the boss structure protrudes relative to the support plate, and the outer end face is flush with the support plate. The support plate has an inwardly protruding rib, and the U-shaped groove is formed on both sides of the rib.

[0010] Preferably, the connecting section is a cylindrical structure, forming a sliding pair and a rotating pair with the U-shaped groove.

[0011] Preferably, each of the connecting segments is fitted with a spring.

[0012] Preferably, the clamp is provided with scale lines, and the clamp block is provided with reference lines.

[0013] Preferably, the working surface of the side clamping block is a V-shaped surface, a circular arc surface, or a plane.

[0014] Preferably, the test fixture is made entirely of a high-temperature resistant alloy.

[0015] A testing method for the aforementioned adaptive ceramic matrix composite tensile testing fixture includes the following steps: S1, install the two clamps onto the upper and lower clamps of the tensile testing machine respectively; adjust the initial opening distance between the two pairs of clamps by sliding the clamps to adapt to the thickness of the sample; S2, place the sample between the upper and lower pairs of clamping blocks; loosen the bolts, and the side clamping blocks fit against the side of the sample, realizing adaptive pre-centering and pre-clamping of the four sides of the sample. S3, tighten the bolt so that the end of the bolt abuts against the connecting section of the side clamp, and securely lock the side clamp in the current position of the U-shaped groove; S4. Start the tensile testing machine and transfer the tensile load to the firmly clamped specimen through the clamps and blocks to perform a tensile test until the specimen breaks or reaches the preset conditions.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This application provides an adaptive ceramic matrix composite tensile testing fixture. Since the clamping blocks can slide on the clamps to adapt to specimens of different thicknesses, and the side clamping blocks slide and rotate in the U-shaped groove through the connecting section, it can adaptively fit the side of specimens of different shapes and lock the position with bolts. This solves the problem that traditional fixtures are difficult to adapt to specimens of multiple specifications and are prone to off-axis loads. Thus, it realizes four-sided adaptive clamping and precise centering of the specimen, which significantly improves clamping stability, test repeatability and data accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an adaptive composite material tensile testing fixture; Figure 2 This is an exploded view of the structure of an adaptive composite tensile testing fixture; Figure 3 This is a schematic diagram of the side clamping block. Figure 4 This is a schematic diagram of the chuck's structure; Figure 5 This is a schematic diagram of the clamping block.

[0018] Wherein: 1-clamp; 2-clamping block; 3-spring; 4-bolt; 5-side clamping block; 6-sample; 101, force application section; 102, clamping section; 103, slide groove; 201, boss structure; 202, support plate; 203, rib plate; 204, U-shaped groove; 205, through hole; 206, slider; 501, connecting section. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings: Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] See Figure 1 and Figure 2This invention discloses an adaptive composite material tensile testing fixture, which includes two opposing clamps 1, clamping blocks 2, springs 3, bolts 4, and side clamping blocks 5. Each clamp 1 comprises two opposing clamps 1, and the inner end of each clamp 1 can be fitted with two opposing clamping blocks 2. Based on the above description, if the relative positional relationship between the two opposing clamps 1 is set as an upper-lower structure, then the positional relationship between the two pairs of clamping blocks 2 is also an upper-lower structure. The two pairs of clamping blocks 2 are completely mirror-symmetrical. Two opposing side clamping blocks 5 are provided between each pair of clamping blocks 2, enabling the clamping of all four sides of the sample 6.

[0021] This fixture, through its multi-degree-of-freedom adjustable clamping components, achieves rapid adaptation and stable clamping of specimens with different geometric dimensions and cross-sectional shapes. The fixture adopts a modular layout. The clamp 1 serves as an external connecting component, used to fix and connect to the upper and lower clamping seats of the tensile testing machine, transferring external loads to the internal clamping mechanism. The clamping block 2 is located at the inner end of the clamp 1, forming the main lateral clamping unit. The side clamping blocks 5 further extend from the clamping block 2, forming a four-way enveloping clamping structure, thereby achieving simultaneous contact and constraint on all four sides of the specimen. The center planes of the two side clamping blocks 5, the two clamping blocks 2, and the two clamping blocks 1 are mutually perpendicular. This spatial orthogonal relationship ensures the symmetry and stress consistency of the fixture in three dimensions, effectively avoiding bending moment or torsional loads caused by structural asymmetry, and improving the coincidence of the loading axis and the specimen axis.

[0022] Each clamping block 2 includes an integrally connected boss structure 201 and a support plate 202, wherein the boss structure 201 is further outward relative to the support plate 202, wherein the outer end faces of the boss structure 201 and the support plate 202 are flush, and the boss structure 201 protrudes inward relative to the support plate 202. The support plate 202 is provided with an inwardly protruding rib 203 inside. The rib 203 is not an external additional structure, but a reinforcing rib-like structure extending from the internal material of the support plate 202, and is symmetrically arranged in the central area along the thickness direction of the clamping block, which has the function of enhancing bending stiffness. The rib plate 203 has U-shaped grooves 204 on both sides. The outer end of the U-shaped groove 204 penetrates the side wall of the clamping block 2. That is, the side wall of the clamping block 2 has a through hole 205, which is connected to the side of the U-shaped groove 204. The upper center of the boss structure 201 and the support plate 202 is provided with an upwardly protruding slider 206, which is connected to the sliding groove 103.

[0023] In the above structure, the presence of the rib plate 203 not only provides a stable mounting base for the U-shaped groove 204, but also optimizes the force transmission path: when the side clamping block 5 is subjected to pressure or clamping reaction force from the side of the sample, this force can be transmitted through the connecting section 501 to the rib plate 203 via the U-shaped groove 204, and then evenly distributed by the rib plate to the entire support plate 202, thereby reducing local stress peaks and improving structural durability. In addition, the inward convex design of the rib plate 203 also reserves more space inside, which is convenient for the embedded arrangement of elastic elements such as the spring 3, achieving functional integration without affecting the external contour. Because the U-shaped groove 204 is set on both sides of the internal rib plate 203, the strength reduction problem caused by large-area slotting on the outside of the clamping block is avoided, and the technical hidden danger of deformation or even breakage due to the weak structure of traditional clamping blocks is solved; at the same time, the introduction of the boss structure 201 enhances the guidance and initial alignment ability when the sample is loaded, reducing manual adjustment time.

[0024] Each side clamp 5 has a connecting section 501 on both sides. Preferably, the connecting section 501 is cylindrical, with one end fixedly connected to the side wall of the side clamp 5 and the other end inserted into the U-shaped groove 204, forming a sliding pair and a rotating pair with the U-shaped groove 204. This dual-degree-of-freedom connection method allows the side clamp 5 to not only adapt to the positional changes of the sample 6 in the thickness direction, but also to automatically adjust its fitting posture according to the tilt angle or curvature of the sample side, improving the adaptability of the fixture to samples with irregular cross-sections.

[0025] In the above structure, the U-shaped groove 204 is an open channel machined inside the clamping block 2, with a "U"-shaped cross-section, allowing the connecting section 501 to be inserted and retaining a certain amount of room for movement. The connecting section 501 can slide along the length of the U-shaped groove 204 and can also rotate around its own axis, thus forming a kinematic pair with both translational and rotational degrees of freedom. This design allows the side clamping block 5 to automatically adjust its position and angle according to the actual side profile of the sample after it is loaded, which is especially suitable for sample surfaces with non-standard rectangular cross-sections or slight deformations, significantly enhancing the adaptability of the fixture. For example, when facing a sample side with slight curvature or taper, the side clamping block 5 can adjust the working surface contact angle by rotation, and at the same time compensate for positional deviations in the width direction by sliding, thereby achieving a tight fit.

[0026] The side wall of clamping block 2 also has a through hole 205 communicating with the U-shaped groove 204 and threadedly connected to bolt 4. When it is necessary to fix the position of side clamping block 5, tighten bolt 4 so that its end presses against the outer surface of connecting section 501, using friction to prevent it from continuing to slide or rotate, thereby locking side clamping block 5 in its current position. Therefore, side clamping block 5 will not slide due to force during the test, and can provide sufficient tensile force to the test piece. This locking mechanism has a simple structure, is easy to operate, and has good repeatability. In some variant embodiments, through hole 205 can be designed as a stepped hole to limit the screw-in depth of bolt 4 and prevent it from excessively pressing and damaging connecting section 501; or, an elastic washer or ball head structure can be added to the end of bolt 4 to increase the contact area and reduce local stress concentration.

[0027] In the above structure, the connecting section 501, as part of the side clamping block 5, extends from both sides into the U-shaped groove 204 on the clamping block 2 to form a through connection; the width of the U-shaped groove 204 is slightly larger than the diameter of the connecting section 501, leaving an appropriate gap to accommodate the space required for movement and to avoid jamming; the bolt 4 passes through the through hole 205 on the side wall of the clamping block 2 and abuts against the outer surface of the connecting section 501, providing sufficient clamping force in the locked state to prevent the side clamping block from shifting due to vibration or load transmission during the test.

[0028] In this invention, the clamp 1 provides basic support and a load input path, the clamp block 2 serves as an intermediate force transmission platform and supports the adjustment mechanism of the side clamp block 5, while the side clamp block 5 directly acts on the sample surface to achieve adaptive fitting and is finally locked by the bolt 4. The entire clamping system, through the sliding and rotational capabilities of the connecting section 501 within the U-shaped groove 204, endows the clamp with tolerance to geometric differences in the sample; combined with the mechanical locking function of the bolt 4, it ensures the stability of the clamping state during testing. The orthogonal configuration between multiple center planes further enhances the symmetry of the system, helping to reduce the risk of eccentric loading.

[0029] In some embodiments of the present invention, each clamp 1 is divided into an integrally connected force-applying section 101 and a clamping section 102. The outer end faces of the force-applying section 101 and the clamping section 102 are integrally connected. The force-applying section 101 is cylindrical, and the inner end face of the clamping section 102 is provided with a sliding groove 103. The clamping block 2 is provided with a slider 206 that mates with the sliding groove 103. The clamping block 2 is installed into the clamp 1 via a guide rail, and the mating method is a transition fit, which can ensure that the clamping block 2 is not easy to slip after installation, thus preventing eccentric load. This detachable guide rail connection method facilitates the replacement of clamps of different specifications to adapt to different models of testing machines, improving the versatility and applicability of the fixture. The slider 206 is embedded in the sliding groove 103, allowing the clamping block 2 to move translationally along the extension direction of the sliding groove 103, thereby adjusting the initial opening distance between the upper and lower pairs of clamping blocks 2 to adapt to ceramic matrix composite samples of different thicknesses. The force-applying section 101 connects to the loading device of the tensile testing machine to transmit external tensile loads; the clamping section 102 serves as the bearing base of the clamping block, providing stable guidance and support. The mating structure between the slide groove 103 and the slider 206 ensures the stability and straightness of the clamping block during movement, preventing misalignment due to skewness or wobbling. The assembled tensile testing fixture is fixed to the testing machine via the cylindrical chuck 1. Different chucks 1 can be used to adapt to different testing machines.

[0030] As an optional implementation, the sliding of the slider 206 within the groove 103 can be manually adjusted, or it can be combined with a drive mechanism such as a lead screw or cylinder to achieve electric or automatic distance adjustment, thereby improving operating efficiency and positioning accuracy. To further improve the convenience of adjustment, scale markings can be set on the clamps, and corresponding baselines can be provided on the clamps to facilitate intuitive judgment of whether the clamps on both sides are symmetrically distributed.

[0031] Furthermore, the chute can be arranged axially along the inner end face of the clamping section, and its cross-sectional shape can be selected as a rectangular, T-shaped or dovetail shape, etc., to meet different guiding accuracy and lateral force resistance requirements.

[0032] In a preferred example, slider 206 and groove 103 form a dovetail fit structure. Slider 206 has a trapezoidal convex cross-section, with the angle between its two inclined surfaces and the horizontal plane ranging from 45° to 75°, optionally 60°, to balance ease of installation and anti-detachment performance. Due to the effective limitation of lateral displacement by the dovetail structure, clamp 2 remains symmetrical to the center plane of clamp 1 during adjustment, avoiding load eccentricity problems caused by offset installation. Simultaneously, this structure enhances the overall connection rigidity, reduces micro-swaying under dynamic loading, and improves the stability and repeatability of test data.

[0033] In some embodiments of the present invention, a spring 3 is fitted onto each connecting segment 501. A bolt 4 is inserted into each through hole 205. The thrust generated by the spring drives the side clamping block 5 to move towards the center along the U-shaped groove 204 until it contacts the sample surface; the springs on both sides act synchronously, applying equal and opposite forces, causing the two oppositely arranged side clamping blocks to tend towards a symmetrical and centered position, effectively avoiding off-axis loads. The stiffness of the spring 3 can be adjusted according to the clamping requirements of samples of different specifications. The connecting segment 501 and the U-shaped groove 204 form a sliding pair and a rotating pair, allowing the side clamping block to translate in the X and Y planes and rotate around the Z axis. Combined with the self-centering force provided by the spring, the side clamping block can automatically adapt to the slight tilt or shape deviation of the sample side, achieving multi-degree-of-freedom adaptive fitting.

[0034] Furthermore, by engaging the thread and bolt 4 in the through hole 205, the side clamp can be quickly locked in the U-shaped groove 204 to prevent slippage due to force during the test, thus ensuring clamping stability and the reliability of test force transmission.

[0035] In some embodiments of the present invention, scale lines are added to the chuck 1 and reference lines are added to the clamp block 2 to ensure that the reference line of the clamp block 2 and the chuck 1 are aligned during installation, thereby ensuring that the center line of the entire sample is aligned with the center line of the clamping section cylinder. In the above structure, the scale lines and reference lines together constitute a position feedback system, which can quickly and accurately determine the installation position of the clamp blocks without relying on external measuring tools. The alignment relationship between the two reflects the spatial distribution of the clamp blocks relative to the center line of the chuck. Especially when adjusting the relative position of the clamp blocks in the upper and lower chucks, it can effectively ensure the symmetrical distribution of the two sets of clamp blocks, thereby reducing the risk of loading axis offset caused by installation deviation.

[0036] In some embodiments of the present invention, the working surface of the side clamping block 5 is a V-shaped surface, an arc surface, or a plane. The V-shaped surface is suitable for specimens with cylindrical or approximately circular cross-sections, using two inclined surfaces to symmetrically clamp the curved edge, forming a two-point positioning effect, which helps with automatic centering and limits lateral offset; the arc surface is used to fit the side surface of specimens with convex curved surfaces or tubular structures, and its radius of curvature can be customized according to the typical specimen size; the plane working surface is suitable for rectangular or plate-shaped cross-section specimens, providing stable large-area support, which helps to disperse clamping pressure and reduce pressure per unit area.

[0037] In some embodiments of this invention, the fixture material is selected from high-temperature resistant alloys to adapt to testing conditions of ceramic matrix composites from room temperature to ultra-high temperature. Typical examples include nickel-based alloys (such as Inconel 718 and Inconel 625), cobalt-based alloys, and iron-nickel-based high-temperature alloys. This invention achieves structural stability and functional reliability of the fixture as a whole over a wide temperature range. Because the entire test fixture is made of a high-temperature resistant alloy, it can maintain sufficient rigidity and strength during high-temperature heating processes, and will not experience loosening of the clamps or eccentric loading due to thermal expansion mismatch or material softening. This solves the problem of traditional fixtures being prone to deformation and failure under high-temperature conditions, leading to distorted test results.

[0038] In some optional examples, a force sensor mounted on the chuck 1 or clamping block 2 is used to monitor the preload; a displacement sensor mounted on the clamping block 2 is used to monitor the relative sliding displacement of the clamping block 2. Specifically, the force sensor is mounted on the chuck 1 or clamping block 2, and the displacement sensor is mounted on the clamping block 2 to monitor their relative sliding displacement during the clamping process. The force sensor acquires information about the preload applied to the sample end during clamping, the displacement sensor captures the relative sliding behavior of the clamping block within the clamping section, and the system controller performs logical analysis and state determination based on the acquired multi-source signals, thereby achieving dynamic evaluation of the clamping quality.

[0039] The fixture of the present invention has a compact overall structure, and the installation and adjustment process is simple and intuitive, reducing human error and improving the repeatability and accuracy of test results.

[0040] A second aspect of the present invention discloses a testing method for an adaptive ceramic matrix composite tensile testing fixture, the testing method comprising the following steps: S1, install the two clamps 1 onto the upper and lower clamps of the tensile testing machine respectively; adjust the initial opening distance between the two pairs of clamps 2 by sliding the clamp 2 to adapt to the thickness of the sample 6; the sample 6 is pressed by the clamp 2. At this time, the sample 6 is aligned with the boss structure 201 on the central axis of the clamp 2. The boss structure 201 has a center line to ensure that the sample 6 will not deviate from the center line when pressed. S2, place the sample 6 between the upper and lower pairs of clamping blocks 2; loosen the bolt 4, and the side clamping block 5 fits against the side of the sample 6 to achieve adaptive pre-centering and pre-clamping of the four sides of the sample 6. S3, tighten bolt 4 so that the end of bolt 4 abuts against the connecting section 501 of side clamp 5, firmly locking side clamp 5 in the current position of U-shaped groove 204; mate side clamp 5 with clamp 2 through the through U-shaped groove on clamp 2, and press one side of side clamp 5 against the side of sample 6. Install spring 3 onto the mating section of side clamp 5 and clamp 2. Spring 3 applies a force of the same magnitude but opposite direction to side clamp 5, ensuring that the center plane of side clamp 5 and the centerline of sample 6 are in the same plane in the tensile direction. Clamp 2 has a through threaded hole on its side corresponding to the U-shaped groove. Connect bolt 4 to clamp 2, keeping the bottom surface of bolt 4 in contact with the cylindrical surface of the mating section of side clamp 5 and clamp 2, thereby restricting the movement of side clamp 5 and ensuring that sample 6 is subjected to sufficient force during the test. After installing clamp 2, spring 3, bolt 4, side clamp 5 and sample 6, connect clamp 2 and chuck 1 through guide rail. The chuck 1 has a scale, which can ensure the centering of sample 6 during installation.

[0041] S4. Start the tensile testing machine and transfer the tensile load to the firmly clamped specimen 6 through the clamp 1 and clamp 2 to perform the tensile test until the specimen 6 breaks or the preset conditions are met.

[0042] The tensile testing machine starts operating according to a preset loading mode, such as constant rate displacement control or force control. The upper and lower clamps cause the clamp 1 to separate axially, thus transmitting the tensile force step-by-step through clamp 1 → clamp block 2 → boss structure 201 → end of specimen 6. Because precise alignment and reliable clamping have been achieved beforehand, the load line of action is essentially coincident with the specimen axis, avoiding the introduction of bending moment and stress concentration. This structural design ensures specimen alignment when clamp 1 is subjected to axial tensile force, preventing eccentric loads during the test. When specimen dimensions change, the clamps can be adjusted to accommodate these changes. Throughout the loading process, specimen 6 primarily bears uniaxial tensile stress until the material reaches its ultimate tensile strength and fractures, or the test is actively terminated upon meeting predetermined test objectives (such as reaching a certain strain level or completing the creep stage). After fracture, the system records key mechanical parameters such as maximum load, displacement curve, and elastic modulus to evaluate the tensile properties of the ceramic matrix composite material.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, "above" or "below" a second feature may include direct contact between the first and second features, or it may include contact between the first and second features not being in direct contact but through another feature between them.

[0044] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adaptive ceramic matrix composite tensile testing fixture, characterized in that, include: Two clamps (1) are arranged opposite each other, and two clamping blocks (2) are installed on the inner end of each clamp (1). Two side clamping blocks (5) are arranged opposite each other on each clamping block (2). The center planes of the two side clamping blocks (5), the center planes of the two clamping blocks (2) and the center planes of the two clamps (1) are perpendicular to each other. Each of the side clamps (5) is provided with a connecting section (501) on both sides. The clamp (2) is provided with a U-shaped groove (204) for the connecting section (501) to be inserted. The connecting section (501) can slide and rotate in the U-shaped groove (204). The side wall of the clamping block (2) is provided with a through hole (205) communicating with the U-shaped groove (204), and a bolt (4) for locking the position of the side clamping block (5) is provided in the through hole (205).

2. The adaptive ceramic matrix composite tensile testing fixture according to claim 1, characterized in that, Each of the clamps (1) includes an integrally connected force-applying section (101) and a clamping section (102). The inner end face of the clamping section (102) is provided with a groove (103), and the clamping block (2) is provided with a slider (206) that cooperates with the groove (103).

3. The adaptive ceramic matrix composite tensile testing fixture according to claim 2, characterized in that, The slider (206) and the groove (103) form a dovetail fit structure.

4. The adaptive ceramic matrix composite tensile testing fixture according to claim 2, characterized in that, The clamping block (2) includes an integrally connected boss structure (201) and a support plate (202). The inner end face of the boss structure (201) protrudes relative to the support plate (202), and the outer end face is flush with the support plate (202). The support plate (202) is provided with an inwardly protruding rib (203) inside, and the U-shaped groove (204) is opened on both sides of the rib (203).

5. The adaptive ceramic matrix composite tensile testing fixture according to claim 1, characterized in that, The connecting section (501) is a cylindrical structure, forming a sliding pair and a rotating pair with the U-shaped groove (204).

6. The adaptive ceramic matrix composite tensile testing fixture according to claim 1, characterized in that, Each of the connecting segments (501) is fitted with a spring (3).

7. The adaptive ceramic matrix composite tensile testing fixture according to claim 1, characterized in that, The clamp (1) is provided with scale lines, and the clamp block (2) is provided with reference lines.

8. The adaptive ceramic matrix composite tensile testing fixture according to claim 1, characterized in that, The working surface of the side clamp (5) is a V-shaped surface, a circular arc surface, or a plane.

9. The adaptive ceramic matrix composite tensile testing fixture according to any one of claims 1-8, characterized in that, The test fixture is made entirely of a high-temperature resistant alloy.

10. A testing method for the adaptive ceramic matrix composite tensile testing fixture of claim 1, characterized in that, Includes the following steps: S1, install the two clamps (1) onto the upper and lower clamps of the tensile testing machine respectively; adjust the initial opening distance between the two pairs of clamps (2) by sliding the clamps (2) to adapt to the thickness of the sample (6); S2, place the sample (6) between the upper and lower pairs of clamping blocks (2); loosen the bolt (4), and the side clamping block (5) fits against the side of the sample (6) to achieve adaptive pre-centering and pre-clamping of the four sides of the sample (6); S3, tighten the bolt (4) so ​​that the end of the bolt (4) abuts against the connecting section (501) of the side clamp (5) and securely lock the side clamp (5) in the current position of the U-shaped groove (204); S4, start the tensile testing machine, and transfer the tensile load to the firmly clamped specimen (6) through the clamp (1) and clamp (2) to perform tensile testing until the specimen (6) breaks or reaches the preset condition.

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