An apparatus and method for testing interlaminar bond strength of a brittle fiber mat

Abstract

This invention relates to a device and method for testing the interlayer bond strength of brittle fiber mats. The testing device includes a worktable, a Z-axis linear module, an X-axis linear module, a force gauge, a clamping and fixing structure, a gasket, an online imaging device, and a control and data processing system. The Z-axis linear module is fixed to the worktable, the X-axis linear module is fixed to the Z-axis linear module slider, and the force gauge is fixed to the X-axis linear module slider. The clamping and fixing structure includes a base and two clamping fixtures, with the gasket held at both ends by the fixtures. This invention uses indirect clamping with gaskets to avoid fiber breakage and slippage caused by direct clamping of the sample, eliminating clamping interference. The dual linear modules work together to achieve oblique upward progressive peeling, avoiding violent tearing of the sample and ensuring accurate and repeatable test results. The accompanying online imaging device enables real-time observation of the peeling process, facilitating the establishment of a correlation between macroscopic mechanical response and microscopic damage mechanism, effectively improving the completeness of test data and the depth of mechanism analysis.

Description

Technical Field

[0001] This invention belongs to the field of mechanical property testing technology for textile materials, and in particular relates to a device and method for testing the interlayer bond strength of brittle fiber felts. Background Technology

[0002] Brittle fiber mats (such as glass fiber mat, ceramic fiber mat, and carbon fiber needle-punched mat) are important composite material reinforcements and functional materials. Due to their lightweight, high-temperature resistance, corrosion resistance, and excellent insulation properties, they are widely used in key fields such as aerospace, new energy, rail transportation, and building insulation. Interlaminar bond strength is a core indicator for evaluating the structural integrity and service reliability of these materials, directly affecting the impact resistance, fatigue life, and long-term stability of composite components. Insufficient interlaminar bond strength can easily lead to interlaminar delamination and debonding failures during material molding or actual service, not only limiting their application range but also potentially posing a serious threat to structural safety.

[0003] However, due to the inherent structural characteristics of brittle fiber mats, existing interlayer bond strength testing methods have significant limitations, mainly in the following aspects:

[0004] Firstly, traditional clamping methods can easily damage the sample. The internal fibers of brittle fiber felt mainly form a network structure through overlapping and interweaving, lacking high crimp or strong entanglement between fibers. When directly clamped by traditional pneumatic clamps, the instantaneous clamping force can easily cause the internal fibers to break or slip; at the same time, because the surface of the clamp is smooth, the sample is prone to slipping during the test, resulting in poor repeatability of test results and large deviations in measurement data.

[0005] Secondly, the load application direction is unidirectional, making it difficult to achieve effective peeling. Existing tests mostly use vertical loading methods, but brittle fiber mats are prone to brittle fracture near the peeling point under vertical loads, which cannot truly reflect the bonding performance of the interlayer interface. The test process often cannot achieve gradual peeling smoothly, affecting the accuracy of the evaluation.

[0006] Third, there is a lack of real-time observation and analysis methods for the peeling process. Existing technologies typically cannot simultaneously record the failure modes during the peeling process, making it difficult to establish the correlation between macroscopic mechanical response and microscopic damage mechanism, thus limiting the guiding value of test results in materials optimization and engineering applications.

[0007] Therefore, there is an urgent need to develop a test method for interlayer bond strength that can adapt to the structural characteristics of brittle fiber felt, avoid sample damage, achieve stable peeling, and support process observation, so as to improve the reliability and scientific nature of the test results. Summary of the Invention

[0008] The main objective of this invention is to provide a device and method for testing the interlayer bond strength of brittle fiber mats, which can effectively solve the problems in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] An apparatus for testing the interlaminar bond strength of brittle fiber mats, comprising:

[0011] Workbench;

[0012] The Z-axis linear module is fixed on the worktable;

[0013] The X-axis linear module is fixed on the slider of the Z-axis linear module;

[0014] The force gauge is fixed on the slider of the X-axis linear module;

[0015] A clamping and fixing structure includes a base fixed to the worktable, on which two clamping fixtures are mounted;

[0016] The gasket is clamped and fixed at both ends by two clamping fixtures, and the brittle fiber felt sample is attached to the gasket.

[0017] An online imaging device is used to capture the dynamic process of peeling off brittle fiber felt samples in real time and collect data on the morphology, displacement and deformation of the fibers.

[0018] The control and data processing system is electrically connected to the motors, force gauges, and online imaging devices of the Z-axis linear module and the X-axis linear module, respectively.

[0019] Preferably, the gasket is a stainless steel gasket.

[0020] Preferably, the length and width of the gasket are both greater than the length and width of the brittle fiber felt sample.

[0021] Preferably, a guide rail is fixedly installed on the base, and two clamping support seats are slidably installed on the guide rail, with the two clamping clamps respectively fixedly installed on the two clamping support seats.

[0022] Preferably, the clamping fixture is detachably mounted on the clamping support by means of a nut.

[0023] Preferably, the online imaging device consists of a light source and a slit element.

[0024] Preferably, the light source adopts a combination structure of a coaxial polarized light source and a gradient backlight light source.

[0025] Preferably, the slit element is a precision adjustable metal slit made of blackened stainless steel foil.

[0026] The present invention also provides a method for testing the interlaminar bond strength of brittle fiber mats, using the aforementioned interlaminar bond strength testing device for brittle fiber mats, specifically including the following steps:

[0027] Step 1: Sample preparation. Select the brittle fiber felt sample to be tested. Make a peeling cut along the length of the side centerline of the brittle fiber felt sample. Peel the fiber felt to 1 / 10 of its length to form the peeling start. Use glue to fully cover the lower layer and the upper peeling start of the brittle fiber felt sample. Attach a hook to the upper peeling start and attach the lower layer to the stainless steel gasket for easy subsequent testing.

[0028] Step 2: Clamping and positioning. Place both ends of the pad into the two clamping fixtures and lock them in place. Then, adjust the position of the force gauge through the X-axis linear module to ensure that the force gauge hook and the sample hook are on the same vertical line. Then, adjust the height of the force gauge through the Z-axis linear module to make the force gauge hook and the sample hook accurately engage. Finally, make the force value display of the force gauge stable within the range of 0±0.1N to complete the clamping and positioning of the sample.

[0029] Step 3: Parameter setting. Set the slider movement speed of the X-axis linear module through the control and data processing system, that is, set the left and right movement speed of the force gauge, and then set the slider movement speed of the Z-axis linear module, that is, set the up and down movement speed of the force gauge.

[0030] Step 4: Start the online imaging device and adjust the imaging-related parameters;

[0031] Step 5: The control and data processing system controls the slider of the X-axis linear module to move to the left, and at the same time controls the slider of the Z-axis linear module to move upward, so that the force gauge moves obliquely upward. The force gauge pulls the peeling start of the brittle fiber felt sample for peeling. During the peeling process, the values ​​measured by the force gauge and the images captured by the online imaging device are transmitted to the control and data processing system in real time. The values ​​measured by the force gauge are the peeling force, and the images captured by the online imaging device record the dynamic process of peeling of the brittle fiber felt sample, thereby collecting its fiber morphology, displacement and deformation data.

[0032] Step 6: When the peeling displacement reaches the preset peeling length of the sample, or the peeling force decreases by more than 95%, stop the equipment operation and the test ends.

[0033] After the test, the control and data processing system automatically plots the peel force-displacement curve and calculates the maximum interlayer peel strength, i.e., the interlayer bond strength, based on the peak value of the curve. The calculation formula is as follows:

[0034] ;

[0035] In the formula, F represents the interlayer bond strength, expressed in MPa. max is the peak force of the peel force-displacement curve, in N; S is the adhesive contact area between the peeling start point of the sample and the adhesive, in mm².

[0036] On the other hand, the control and data processing system 8 converts the images captured by the online imaging device 7 into digital image signals, and processes them through digital image correlation algorithms to obtain microscopic evolution data of fiber fracture location and deformation rate during the sample peeling process.

[0037] This invention provides an apparatus and method for testing the interlayer bond strength of brittle fiber mats, which has the following advantages:

[0038] 1. In this invention, the brittle fiber felt sample is pasted and placed on a pad, and the two ends of the pad are clamped and fixed by two clamping fixtures. This indirect clamping method prevents the clamping fixtures from directly clamping the brittle fiber felt sample, thereby avoiding the clamping force causing the internal fibers of the brittle fiber felt sample to break or slip, and eliminating the interference of the clamping process on the test results.

[0039] 2. This invention, through the collaborative design of the X-axis linear module and the Z-axis linear module, can achieve synchronous linkage control in two directions. During the peel test, the force gauge moves at a constant speed upward along a preset trajectory. This gentle and gradual upward peel method replaces the traditional vertical direct stretching, which can avoid the sample being violently torn apart and achieve stable and effective peeling of the interlayer interface. This more realistically and accurately reflects the bonding performance of the interlayer interface and ensures the accuracy and repeatability of the test results.

[0040] 3. The present invention is also equipped with an online imaging device, which enables real-time observation of the peeling process, facilitates the establishment of the correlation between macroscopic mechanical response and microscopic damage mechanism, effectively improves the integrity of test data and the depth of mechanism analysis, and greatly enhances the theoretical support and technical guidance role of test results for material formulation improvement, interface structure optimization and practical engineering applications. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the interlayer bond strength testing device for brittle fiber felt according to the present invention.

[0042] Figure 2 This is a schematic diagram of the clamping and fixing structure of the present invention.

[0043] In the diagram: 1. Workbench; 2. Z-axis linear module; 3. X-axis linear module; 4. Force gauge; 5. Clamping and fixing structure; 51. Base; 52. Clamping fixture; 53. Guide rail; 54. Fixture support; 6. Gasket; 7. Online imaging device; 8. Control and data processing system; Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0045] 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," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this 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. Therefore, they should not be construed as limiting this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may 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.

[0047] Reference Figure 1-2 This invention provides a device for testing the interlaminar bond strength of brittle fiber mats, comprising:

[0048] Workbench 1;

[0049] Z-axis linear module 2 is fixed on the worktable 1;

[0050] The X-axis linear module 3 is fixed on the slider of the Z-axis linear module 2;

[0051] Force gauge 4 is fixed on the slider of the X-direction linear module 3;

[0052] The clamping and fixing structure 5 includes a base 51 fixed on the worktable 1, and two clamping fixtures 52 are mounted on the base 51.

[0053] The gasket 6 is clamped and fixed at both ends by the two clamping clamps 52, and the brittle fiber felt sample is attached and placed on the gasket 6.

[0054] Online imaging device 7 is used to capture the dynamic process of peeling off brittle fiber felt samples in real time and collect data on the morphology, displacement and deformation of its fibers.

[0055] The control and data processing system 8 is electrically connected to the motors, force gauges 4, and online imaging devices 7 of the Z-axis linear module 2 and the X-axis linear module 3, respectively.

[0056] In this invention, the force gauge 4 is fixed on the slider of the X-direction linear module 3. When the slider of the X-direction linear module 3 moves, it can drive the force gauge 4 to move left and right. The X-direction linear module 3 is fixed on the slider of the Z-direction linear module 2. When the slider of the Z-direction linear module 2 moves, it can drive the X-direction linear module 3 to move up and down, which in turn can drive the force gauge 4 to move up and down.

[0057] It should be noted that the Z-axis linear module 2 and the X-axis linear module 3 can be ball screw modules, synchronous belt modules, linear motor modules or gear and rack modules, which can be selected according to specific circumstances, as long as the force gauge 4 can move up, down and left and right. This invention does not limit them, and all of them are within the protection scope of this invention.

[0058] The control and data processing system 8 is electrically connected to the motors of the Z-axis linear module 2 and the X-axis linear module 3, the force gauge 4, and the online imaging device 7, respectively. By controlling the motors of the Z-axis linear module 2 and the X-axis linear module 3, the control and data processing system 8 can control the force gauge 4 to move up, down, left, and right. The values ​​measured by the force gauge 4 and the images captured by the online imaging device 7 can be transmitted to the control and data processing system 8 in real time for further processing.

[0059] The present invention also provides a method for testing the interlaminar bond strength of brittle fiber mats, using the aforementioned interlaminar bond strength testing device for brittle fiber mats, specifically including the following steps:

[0060] Step 1: Sample preparation. Select the brittle fiber felt sample to be tested. Make a peeling cut along the length of the side centerline of the brittle fiber felt sample. Peel the fiber felt to 1 / 10 of its length to form the peeling start. Use glue to fully cover the lower layer and the upper peeling start of the brittle fiber felt sample. Attach a hook to the upper peeling start and attach the lower layer to the stainless steel gasket at point 6 for easy subsequent testing.

[0061] Step 2: Clamping and positioning. Place both ends of the pad 6 into the two clamping fixtures 52 and lock them in place. Then, adjust the position of the force gauge 4 through the X-axis linear module 3 to ensure that the hook of the force gauge 4 and the sample hook are on the same vertical line. Then, adjust the height of the force gauge 4 through the Z-axis linear module 2 to make the hook of the force gauge 4 and the sample hook accurately engage. Finally, make the force value display of the force gauge 4 stable within the range of 0±0.1N to complete the clamping and positioning of the sample.

[0062] Step 3: Parameter setting. Set the slider movement speed of the X-axis linear module 3 through the control and data processing system 8, that is, set the left and right movement speed of the force gauge 4, and then set the slider movement speed of the Z-axis linear module 2, that is, set the up and down movement speed of the force gauge 4.

[0063] Step 4: Start the online imaging device 7 and adjust the imaging-related parameters;

[0064] Step 5: The control and data processing system 8 controls the slider of the X-axis linear module 3 to move to the left, and at the same time controls the slider of the Z-axis linear module 2 to move upward, so that the force gauge 4 moves obliquely upward. The force gauge 4 pulls the peeling start end of the brittle fiber felt sample to peel. During the peeling process, the values ​​measured by the force gauge 4 and the images captured by the online imaging device 7 are transmitted to the control and data processing system 8 in real time. The values ​​measured by the force gauge 4 are the peeling force, and the images captured by the online imaging device 7 record the dynamic process of peeling of the brittle fiber felt sample, thereby collecting its fiber morphology, displacement and deformation data.

[0065] Step 6: When the peeling displacement reaches the preset peeling length of the sample, or the peeling force decreases by more than 95%, stop the equipment operation and the test ends.

[0066] After the test, the control and data processing system 8 automatically plots the peel force-displacement curve and calculates the maximum interlayer peel strength, i.e., the interlayer bond strength, based on the peak value of the curve. The calculation formula is as follows:

[0067] ;

[0068] In the formula, F represents the interlayer bond strength, expressed in MPa. maxis the peak force of the peel force-displacement curve, in N; S is the adhesive contact area between the peeling start point of the sample and the adhesive, in mm².

[0069] On the other hand, the control and data processing system 8 converts the images captured by the online imaging device 7 into digital image signals, and processes them through digital image correlation algorithms to obtain microscopic evolution data of fiber fracture location and deformation rate during the sample peeling process.

[0070] In this invention, the brittle fiber felt sample is pasted and placed on the pad 6. The two ends of the pad 6 are clamped and fixed by two clamping fixtures 52. This indirect clamping method prevents the clamping fixtures 52 from directly clamping the brittle fiber felt sample, thereby avoiding the clamping force causing the internal fibers of the brittle fiber felt sample to break or slip, and eliminating the interference of the clamping process on the test results.

[0071] This invention achieves synchronous linkage control in two directions through the collaborative design of the X-direction linear module 3 and the Z-direction linear module 2. During the peel test, the force gauge 4 is driven to move obliquely upward at a uniform speed along a preset trajectory. This gentle and gradual oblique upward peel method replaces the traditional vertical direct stretching, which can avoid the sample being violently torn apart and achieve stable and effective peeling of the interlayer interface. This more realistically and accurately reflects the bonding performance of the interlayer interface and ensures the accuracy and repeatability of the test results.

[0072] The present invention is also equipped with an online imaging device 7, which enables real-time observation of the peeling process, facilitates the establishment of the correlation between macroscopic mechanical response and microscopic damage mechanism, effectively improves the integrity of test data and the depth of mechanism analysis, and greatly enhances the theoretical support and technical guidance role of test results for material formulation improvement, interface structure optimization and practical engineering applications.

[0073] As a preferred implementation, in step S1, after selecting the brittle fiber felt sample to be tested, it is first cut into rectangular samples with a size of 25mm × 150mm. Then, the brittle fiber felt sample is placed in a constant temperature and humidity chamber at 25℃ and 65% relative humidity for 24 hours to achieve humidity equilibrium. After equilibrium, the thickness of the sample is measured. The core purpose of this step is to ensure the accuracy, stability, and comparability of the test data: First, to eliminate the influence of the environment, 25℃ and 65%RH are the standard environment for material testing. Humidity equilibrium for 24 hours allows the sample to reach moisture absorption and dehumidification equilibrium, avoiding the thermal expansion and contraction of the fibers and moisture absorption and dehumidification caused by temperature and humidity, and preventing the deformation of the sample itself from interfering with the test; Second, to ensure accurate thickness measurement, the sample is stable after equilibrium, which can avoid thickness measurement deviation and ensure the reliability of subsequent calculations of bonding area and interlayer bonding strength.

[0074] As a preferred embodiment, the gasket 6 is a stainless steel gasket 6. Stainless steel has high strength, high rigidity, and good flatness, and is not easily deformed. It can provide a stable and flat support base for brittle fiber felt samples, avoiding uneven stress on the sample due to deformation of the gasket 6, thereby preventing premature sample breakage or distortion of test force values. At the same time, stainless steel is corrosion-resistant and not easily oxidized, and can be reused for a long time, reducing testing costs. Its smooth surface is not slippery and can form a good bonding effect with adhesive, ensuring that the lower layer of the sample is firmly attached to the gasket 6, avoiding relative slippage between the sample and the gasket 6 during the peeling process, and ensuring the stability of the testing process and the accuracy of the test results.

[0075] As a preferred embodiment, the length and width of the gasket 6 are both greater than the length and width of the brittle fiber felt sample. This enables full coverage support of the sample, ensuring uniform stress on the sample throughout the test. At the same time, the larger gasket 6 provides sufficient operating space, facilitating the pasting, fixing, and clamping of the sample, and preventing contact or damage to the sample during clamping.

[0076] As a preferred embodiment, a guide rail 53 is fixedly installed on the base 51, and two clamping support seats 54 are slidably installed on the guide rail 53. The two clamping fixtures 52 are respectively fixedly installed on the two clamping support seats 54. The cooperation between the guide rail 53 and the slidable clamping support seats 54 can flexibly adjust the distance between the two clamping fixtures 52, adapt to gaskets 6 and brittle fiber felt samples of different lengths, and improve the versatility of the testing device.

[0077] As a preferred embodiment, the clamping fixture 52 is detachably mounted on the clamping support 54 by means of a nut. The detachable design allows for flexible replacement of the appropriate clamping fixture 52 according to the thickness, width and other specifications of the gasket 6, thereby expanding the applicability of the testing device and adapting to the testing needs of samples of different sizes.

[0078] As a preferred embodiment, the online imaging device 7 consists of a light source and a slit element. The light source provides sufficient and stable light for imaging, while the slit element can constrain and filter the light, filtering stray light interference and focusing the light on the interlayer peeling area of ​​the sample, clearly presenting the fine structure of the fibers. The two work together to effectively improve the clarity and contrast of the image, ensuring that the online imaging device 7 can accurately capture the morphological changes, displacement, and fracture moments of the fibers during the peeling process. This provides a high-quality image foundation for subsequent image processing through algorithms to obtain microscopic data on fiber fracture location and deformation rate, thereby establishing a correlation between macroscopic peeling force data and microscopic damage mechanisms, and improving the depth and accuracy of the test.

[0079] As a preferred embodiment, the light source adopts a combination structure of coaxial polarized light source and gradient backlight source. The coaxial polarized light source can specifically solve the problem that the surface of brittle fibers is smooth and prone to diffuse reflection, resulting in blurred imaging and unclear fiber edges. By suppressing diffuse reflection, the outline and shape of the fiber are clearly presented, which is convenient for observing the stretching and deformation process of the fiber. The adjustable brightness design of the gradient backlight source can flexibly adjust the brightness according to the thickness of the sample, fiber density and void distribution, avoiding the inability to identify interlayer voids due to excessively strong or weak light. It can adapt to the testing of brittle fiber felt samples of different specifications and structures, ensuring that the details of the interlayer structure can be clearly captured regardless of the size of the interlayer voids or the density of fiber interweaving. This provides comprehensive and accurate image data for microscopic mechanism analysis, further improving the reliability and practicality of the test results.

[0080] As a preferred embodiment, the slit element is a precision adjustable metal slit made of blackened stainless steel foil. The precision adjustable design allows for flexible adjustment of the slit width and angle according to imaging requirements, precisely controlling the amount of light transmitted and the illumination range. This ensures that the light can be accurately focused on the interlayer peeling area of ​​the sample, avoiding excessively wide light that leads to blurred imaging and increased stray light, or excessively narrow light that results in insufficient imaging range and inability to fully capture the peeling process. The blackened stainless steel foil material has good light-shielding properties, effectively blocking stray light while preventing light reflection and reducing diffraction on the slit surface. This suppresses reflected and diffracted light from interfering with imaging, ensuring the clarity and accuracy of the image.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for testing the interlaminar bond strength of brittle fiber mats, characterized in that, include: Workbench; The Z-axis linear module is fixed on the worktable; The X-axis linear module is fixed on the slider of the Z-axis linear module; The force gauge is fixed on the slider of the X-axis linear module; A clamping and fixing structure includes a base fixed to the worktable, on which two clamping fixtures are mounted; The gasket is clamped and fixed at both ends by two clamping fixtures, and the brittle fiber felt sample is attached to the gasket. An online imaging device is used to capture the dynamic process of peeling off brittle fiber felt samples in real time and collect data on the morphology, displacement and deformation of the fibers. The control and data processing system is electrically connected to the motors, force gauges, and online imaging devices of the Z-axis linear module and the X-axis linear module, respectively.

2. The device for testing the interlaminar bond strength of brittle fiber mats according to claim 1, characterized in that, The gasket is a stainless steel gasket.

3. The device for testing the interlaminar bond strength of brittle fiber mats according to claim 1, characterized in that, The length and width of the gasket are both greater than the length and width of the brittle fiber felt sample.

4. The interlaminar bond strength testing device for brittle fiber mats according to claim 1, characterized in that, A guide rail is fixedly installed on the base, and two clamping support seats are slidably installed on the guide rail. The two clamping clamps are respectively fixedly installed on the two clamping support seats.

5. The interlaminar bond strength testing device for brittle fiber mats according to claim 4, characterized in that, The clamping fixture is detachably mounted on the fixture support by means of a nut.

6. The apparatus for testing the interlaminar bond strength of brittle fiber mats according to claim 1, characterized in that, The online imaging device consists of a light source and a slit element.

7. The apparatus for testing the interlaminar bond strength of brittle fiber mats according to claim 6, characterized in that, The light source adopts a combination structure of coaxial polarized light source and gradient backlight light source.

8. The apparatus for testing the interlaminar bond strength of brittle fiber mats according to claim 6, characterized in that, The slit element is a precision adjustable metal slit, and its material is blackened stainless steel foil.

9. A method for testing the interlaminar bond strength of brittle fiber mats, using the interlaminar bond strength testing apparatus for brittle fiber mats as described in any one of claims 1-8, characterized in that, Specifically, the following steps are included: Step 1: Sample preparation. Select the brittle fiber felt sample to be tested. Make a peeling cut along the length of the side centerline of the brittle fiber felt sample. Peel the fiber felt to 1 / 10 of its length to form the peeling start. Use glue to fully cover the lower layer and the upper peeling start of the brittle fiber felt sample. Attach a hook to the upper peeling start and attach the lower layer to the stainless steel gasket for easy subsequent testing. Step 2: Clamping and positioning. Place both ends of the pad into the two clamping fixtures and lock them in place. Then, adjust the position of the force gauge through the X-axis linear module to ensure that the force gauge hook and the sample hook are on the same vertical line. Then, adjust the height of the force gauge through the Z-axis linear module to make the force gauge hook and the sample hook accurately engage. Finally, make the force value display of the force gauge stable within the range of 0±0.1N to complete the clamping and positioning of the sample. Step 3: Parameter setting. Set the slider movement speed of the X-axis linear module through the control and data processing system, that is, set the left and right movement speed of the force gauge, and then set the slider movement speed of the Z-axis linear module, that is, set the up and down movement speed of the force gauge. Step 4: Start the online imaging device and adjust the imaging-related parameters; Step 5: The control and data processing system controls the slider of the X-axis linear module to move to the left, and at the same time controls the slider of the Z-axis linear module to move upward, so that the force gauge moves obliquely upward. The force gauge pulls the peeling start of the brittle fiber felt sample for peeling. During the peeling process, the values ​​measured by the force gauge and the images captured by the online imaging device are transmitted to the control and data processing system in real time. The values ​​measured by the force gauge are the peeling force, and the images captured by the online imaging device record the dynamic process of peeling of the brittle fiber felt sample, thereby collecting its fiber morphology, displacement and deformation data. Step 6: When the peeling displacement reaches the preset peeling length of the sample, or the peeling force decreases by more than 95%, stop the equipment operation and the test ends. After the test, the control and data processing system automatically plots the peel force-displacement curve and calculates the maximum interlayer peel strength, i.e., the interlayer bond strength, based on the peak value of the curve. The calculation formula is as follows: ； In the formula, Interlayer bond strength, in MPa; F max The peak force on the peel force-displacement curve is expressed in N. S represents the bonding contact area between the peeling start point of the sample and the adhesive, in mm². On the other hand, the control and data processing system 8 converts the images captured by the online imaging device 7 into digital image signals, and processes them through digital image correlation algorithms to obtain microscopic evolution data of fiber fracture location and deformation rate during the sample peeling process.

Images