A test device and method

Abstract

The present disclosure relates to a testing device and method. The device comprises a first clamp, a second clamp, a third clamp, a cutting assembly, a loading device and a mounting base; the first clamp, the second clamp and the third clamp are arranged on the mounting base, the mounting base is arranged on the loading device, and the loading device is drivingly connected with the first clamp, the second clamp, the third clamp and the cutting assembly; wherein the first clamp is used for clamping a first end of a sample; the second clamp is used for defining the length of a test section of the sample; the third clamp is used for clamping a second end of the sample; the cutting assembly is used for cutting the test section of the sample; and the loading device is used for driving the first clamp and the third clamp to move away from or close to each other to clamp or release the sample, driving the second clamp to define and clamp the test section, and driving the cutting assembly to apply a load to the sample to cut the test section. The present disclosure can quickly, conveniently, accurately and reasonably test the brittle fracture strength of a fiber material.

Description

Technical Field

[0001] This disclosure relates to the field of carbon fiber performance testing technology, and in particular to a testing apparatus and method. Background Technology

[0002] Carbon fiber is a linear, brittle, anisotropic material, typically with a diameter between 5 and 8 μm. Along the fiber direction, carbon fiber exhibits excellent mechanical strength and modulus; however, perpendicular to the fiber direction, its strength and stiffness decrease significantly, making it prone to brittle fracture, especially under impact stress. The brittleness of carbon fiber greatly affects the fiber breakage rate during use, further impacting the impact resistance, fatigue performance, and fracture toughness of carbon fiber composite products. Therefore, the brittleness of carbon fiber is a key factor in evaluating its processability and the load-bearing capacity and quality of carbon fiber composite products.

[0003] Currently, in engineering applications, the performance evaluation and quality control of carbon fiber typically revolve around its physicochemical and mechanical properties. Physicochemical properties include linear density, bulk density, and sizing agent content, while mechanical properties include tensile strength, modulus, and elongation at break. Furthermore, in scientific research, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD) are commonly used to evaluate the microscopic properties of carbon fiber, such as surface elements, surface and cross-sectional morphology, and degree of carbonization. In the production of carbon fiber prepregs and the manufacturing of composite materials, the current primary method for evaluating the abrasion resistance and processability of carbon fiber during use is by testing its fuzziness. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this disclosure provides a testing apparatus and method.

[0005] According to embodiments of this disclosure, a testing apparatus is provided for testing the brittle fracture strength of fiber materials. The testing apparatus includes a first clamp, a second clamp, a third clamp, a cutting assembly, a loading device, and a mounting base. The first clamp, the second clamp, and the third clamp are disposed on the mounting base, the mounting base is disposed on the loading device, and the loading device is drivenly connected to the first clamp, the second clamp, the third clamp, and the cutting assembly. The first clamp is used to hold the first end of the sample; The second clamp is used to define the length of the test segment of the specimen; The third clamp is used to hold the second end of the sample; The cutting assembly is used to cut the test segment of the specimen; The loading device is used to drive the first clamp and the third clamp away from or towards each other to clamp or release the sample, drive the second clamp to define and hold the test segment, and drive the cutting assembly to apply a load to the sample to cut the test segment.

[0006] In some embodiments, the first clamp includes: A sliding component is mounted on the mounting base; The first sensor, with one end connected to the sliding member, is used to collect the tensile force value of the sample. A first clamping structure is connected to the other end of the first sensor and is used to clamp the first end of the sample.

[0007] In some embodiments, the third clamp includes: The bracket is fixedly installed on the mounting base; The second clamping structure is movably connected to the bracket and is used to clamp the second end of the sample; A driving structure for driving the second clamping structure to move in order to provide a tensile force to the sample; or, The bracket is slidably mounted on the mounting base, the second clamping structure is fixedly connected to the bracket, and the driving structure is used to drive the bracket to move so as to provide tension to the sample.

[0008] In some embodiments, the driving structure is configured to adjust the output tension based on the tension value of the sample collected by the first sensor, and stop adjusting the tension when the tension reaches a set value; The set value is determined based on the width of the sample.

[0009] In some embodiments, the second clamp includes: Two sliding supports are used to place the sample, and the position of the sliding supports can be adjusted by sliding according to the length of the test section; A base is mounted on the mounting base, and two sliding supports are slidably mounted on the base. After the position of the sliding supports is determined, the two sliding supports are fixed on the base to limit the length of the test section of the sample. In some embodiments, the second clamp further includes: A screw drive component, mounted on the base, is connected to the two sliding supports for adjusting the distance between the two sliding supports according to the positions of the two sliding supports and the length of the test section. Two rotatable clamping components are movably connected to the two sliding supports respectively, and are used to clamp the sample; During the clamping process, the two rotatable clamping components rotate from top to bottom and clamp the sample.

[0010] In some embodiments, the second clamp further includes: A lifting structure is installed on the mounting base, and the base is installed on the lifting structure. The lifting structure is used to adjust the height of the base. In some embodiments, elastic portions are respectively installed above the two rotatable clamping members to clamp or release the sample.

[0011] In some embodiments, the loading device includes: The second sensor is used to collect the cutting force value when the sample is cut; The cutting assembly includes: The first connecting part is used to connect with the second connecting part of the second sensor; A cutting component, connected to the first connecting part, is used to cut the test segment of the sample; A fixing component is used to fix the first connecting part and the cutting component.

[0012] According to embodiments of this disclosure, a testing method is provided, executed via the testing apparatus described above, for testing the brittle fracture strength of fiber materials, comprising: Adjust the position of the second clamp according to the length of the test section of the sample; The sample is placed on the second clamp, and the loading device controls the first clamp and the third clamp to move away from each other in order to hold the sample. The loading device controls the cutting assembly to move downwards, cutting the test segment of the sample; The loading device collects the maximum cutting force value when the sample is completely cut, and determines the brittle fracture strength per unit width of the sample based on the maximum cutting force value.

[0013] The technical solution provided in this disclosure may include the following beneficial effects: The loading device controls the second clamp to define and hold the test section of the sample, and controls the first and second clamps to move away from each other to hold the sample, so that the sample is stretched to a set degree. After the sample is clamped, the loading device controls the cutting component to cut the test section of the sample. This can achieve rapid, convenient, accurate and reasonable testing of the brittle fracture strength of fiber materials, which helps to improve the optimization and quality control of the comprehensive performance of carbon fibers and their prepregs and composites.

[0014] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit this document. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0016] Figure 1 This is a perspective view of a testing apparatus according to an exemplary embodiment; Figure 2 This is a perspective view of a loading device according to an exemplary embodiment; Figure 3 This is a schematic diagram illustrating the connection between the cutting assembly and the sliding connector of the loading device according to an exemplary embodiment; Figure 4 This is a perspective view of a first clamp according to an exemplary embodiment; Figure 5 This is a perspective view of a third clamp according to an exemplary embodiment; Figure 6 This is a perspective view of a second clamping device according to an exemplary embodiment; Figure 7 This is a schematic diagram of a limiting member according to an exemplary embodiment; Figure 8 This is a perspective view of a positioning groove according to an exemplary embodiment; Figure 9 This is a perspective view of a cutting assembly according to an exemplary embodiment; Figure 10 This is a flowchart illustrating a test method according to an exemplary embodiment; Figure 11 This is a perspective view of a sample preparation fixture according to an exemplary embodiment.

[0017] Figure Labels 1. First clamp; 11. Sliding member; 12. First sensor; 13. First clamping structure; 2. Second clamp; 21. Sliding support; 211. Limiting groove; 212. Positioning groove; 22. Base; 221. T-slot; 222. Nut; 223. Limiting component; 23. Screw drive component; 24. Rotatable clamping component; 241. Elastic part; 242. Connecting part; 25. Lifting structure; 3. Third clamp; 31. Support; 32. Second clamping structure; 33. Drive structure; 4. Cutting assembly; 41. First connecting part; 42. Cutting component; 43. Fixing component; 5. Loading device; 51. Sliding connector; 52. Second sensor 6. Install the base; 7. Sample preparation fixture; 71. Table; 72. Pressure component; 73. Pressure plate; 74. Counterweight; 75. Carbon fiber tow sample. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure 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 disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0019] The brittleness of linear fiber materials and its testing methods have attracted attention since the early stages of the large-scale application of glass fiber materials. In the 20th century, research has reported brittleness testing methods such as torsion test, looping test, and fracture work test.

[0020] The torsion method involves taking a fiber with a length of l and a diameter of d, fixing one end of it, and torsion the other end. When the other end is torsiond n times, the fiber breaks. The brittleness α of the fiber is calculated using the formula tgα=l / (πdn). The larger α is, the more brittle the fiber is.

[0021] The looping method involves looping the fiber and then gently pulling on both ends to gradually shrink the loop until the fiber breaks. The diameter ρ of the loop and the diameter d of the fiber are measured just before breakage. The brittleness of the fiber is characterized by the ratio d / ρ; the smaller the ratio, the more brittle the fiber.

[0022] The fracture work method calculates the external energy absorbed when the fiber breaks by testing the fiber's tensile curve (i.e., fracture work). The greater the fracture work, the stronger the fiber's resistance to tensile fracture.

[0023] Of the three methods mentioned above, the torsion method and the looping method indirectly characterize fiber brittleness by using the shape and deformation data at the time of fiber brittle fracture. The fracture work method actually tests the external energy absorbed by the fiber when it breaks under tension along the fiber axis, reflecting the fiber's ability to resist tensile fracture in the axial direction. These methods are controversial in terms of their rationality and accuracy in characterizing fiber brittleness, and therefore have not been widely used subsequently.

[0024] To address the aforementioned problems, this disclosure provides a testing device for testing the brittle fracture strength of fiber materials. Fiber brittleness is primarily manifested in the tendency of fibers to fracture brittlely when subjected to force perpendicular to the fiber axis. Brittle fracture refers to a fracture mode with a smooth fracture end and no plastic deformation. Brittle fracture strength can be defined as the maximum external force a fiber can withstand when undergoing brittle fracture. The testing device includes a first clamp, a second clamp, a third clamp, a cutting assembly, a loading device, and a mounting base. The first clamp is used to hold the first end of the sample, the second clamp is used to define the length of the test segment of the sample, the third clamp is used to hold the second end of the sample, and the cutting assembly is used to cut the test segment of the sample. The first, second, and third clamps are mounted on the mounting base, which is mounted on the loading device. The loading device is driven to connect to the first, second, and third clamps and the cutting assembly. The loading device can drive the first and third clamps to move away from or towards each other to clamp or release the sample, drive the second clamp to define and hold the test segment, and drive the cutting assembly to apply a load to the sample to cut the test segment. Therefore, this disclosure enables the testing of the maximum cutting force at which the fiber breaks during fiber cutting, achieving rapid, convenient, accurate and reasonable testing of the brittle fracture strength of fiber materials, which helps to optimize and control the overall performance of carbon fibers and their prepregs and composites.

[0025] According to an exemplary embodiment of this disclosure, such as Figure 1 and Figure 2 As shown, this embodiment provides a testing device, which includes a first clamp 1, a second clamp 2, a third clamp 3, a cutting assembly 4, a loading device 5, and a mounting base 6. The first clamp 1, the second clamp 2, and the third clamp 3 are mounted on the mounting base 6, and the mounting base 6 is mounted on the loading device 5. The loading device 5 is drivenly connected to the first clamp 1, the second clamp 2, the third clamp 3, and the cutting assembly 4. Its function is to drive the first clamp 1 and the third clamp 3 away from or towards each other to clamp or release the sample, drive the second clamp 2 to define and clamp the test segment, and drive the cutting assembly 4 to apply a load to the sample to cut the test segment.

[0026] In some embodiments, the first clamp 1 may also be called a fixed end clamp, which is used to clamp the first end of the sample; the second clamp 2 may also be called a cutting clamp, which is used to limit the length of the test section of the sample, and the test section may also be called the cutting part; the third clamp 3 may also be called a moving end clamp, which is used to clamp the second end of the sample; the cutting component 4 may also be called a blade assembly, which is used to cut the test section of the sample.

[0027] In some embodiments, the cutting component 4 can cut the sample at a set speed, and the loading device 5 can control the magnitude of the set speed.

[0028] In one example, the mounting base 6 can be any structure that can support the first clamp 1, the second clamp 2 and the third clamp 3. For example, the mounting base 6 can be a square aluminum profile. The first clamp 1, the second clamp 2 and the third clamp 3 can be set on the mounting base 6 in any way, such as being fixedly installed on the mounting base 6, or being fixedly installed on the mounting base 6 by screws.

[0029] In some embodiments, adjustable mechanisms may be installed at the left and right ends of the mounting base 6, and these adjustable mechanisms are used to adjust the horizontal height of the mounting base 6. In one example, the adjustable mechanism may be an adjustable foot cup.

[0030] In some embodiments, the mounting base 6 can be connected to the loading device 5, for example, via a connector.

[0031] In some embodiments, the mounting base 6 can serve as a fixed crossbeam for the loading device 5, and the first clamp 1, the second clamp 2, and the third clamp 3 are respectively connected to the fixed crossbeam of the loading device 5, such as... Figure 3 As shown, the loading device 5 also includes a sliding connector 51. The cutting component 4 is connected to the sliding connector 51 of the loading device 5, so that the cutting component 4 moves at a set speed along a direction perpendicular to the sample through the sliding connector 51 to cut the test section of the sample.

[0032] In one example, male connectors are provided on the first clamp 1, the second clamp 2, the third clamp 3, and the cutting component 4, while female connectors are provided on the fixed crossbeam and the sliding connector. The connection of the male and female connectors enables the connection between the first clamp 1, the second clamp 2, the third clamp 3 and the fixed crossbeam, as well as the connection between the cutting component 4 and the sliding connector 51.

[0033] The loading device 5 includes a driving mechanism, which is driven and connected to a sliding member. The driving mechanism drives the sliding member at a set speed, which drives the cutting component 4 to cut the sample downward in a direction perpendicular to the sample. This allows for testing the maximum cutting force value when the fiber breaks during fiber cutting, enabling a fast, convenient, accurate and reasonable test of the brittle fracture strength of fiber materials.

[0034] The drive mechanism may include a servo driver and a servo motor. The servo driver controls the servo motor to move the slider, causing the slider to move downwards at a set speed, thereby moving the cutting component 4 and completing the cutting of the test segment of the sample.

[0035] In one example, the loading device 5 can be a single-column electronic universal testing machine, which is not limited by equipment space in the lateral direction.

[0036] In some embodiments, such as Figure 4As shown, the first clamp 1 includes a sliding member 11, a first sensor 12, and a first clamping structure 13. The sliding member 11 is mounted on the mounting base 6 and can slide up and down relative to the mounting base 6 to adjust the horizontal height of the sample, ensuring that the sample remains horizontal when clamped by adjusting the position of the sliding member 11. One end of the first sensor 12 is connected to the sliding member 11, and the other end is connected to the first clamping structure 13. The first sensor 12 is used to collect the tensile force value of the sample, and the first clamping structure 13 is used to clamp the first end of the sample. In one example, the first sensor 12 can be connected to the sliding member 11 at one end and to the first clamping structure 13 at the other end via a sensor connecting plate.

[0037] In some embodiments, the sliding member 11 can be a slide table, the first sensor 12 can be a load sensor, and the first clamping structure 13 can be a pneumatic clamp. The pneumatic clamp controls the clamp to hold or release the sample via a dedicated foot switch. The pneumatic clamp works in conjunction with the third clamp 3 to stretch the sample, ensuring that the axial clamping force on the sample remains consistent after installation.

[0038] In one example, the rated capacity of the load sensor is ≤500N, and the force measurement error of the load sensor is ≤0.5%.

[0039] In some embodiments, such as Figure 5 As shown, the third clamp 3 includes a bracket 31, a second clamping structure 32, and a driving structure 33. The bracket 31 is fixedly mounted on the mounting base 6. The second clamping structure 32 is movably connected to the bracket 31 and is used to clamp the second end of the sample. The driving structure 33 drives the second clamping structure 32 to move backward (in the direction of the bracket) to provide tension to the sample, so as to cooperate with the first clamp 1 to hold the sample, so that the sample is in a horizontal state, and at the same time, the axial force on the sample is at a set value, which is suitable for cutting tests.

[0040] In some embodiments, the bracket 31 is slidably mounted on the mounting base 6, the second clamping structure 32 is fixedly connected to the bracket 31, and the driving structure 33 drives the bracket 31 to move backward (away from the direction of the first clamp 1) to provide tension to the sample, so that the second clamping structure 32 cooperates with the first clamp 1 to hold the sample, so that the sample is in a horizontal state, and at the same time the axial force on the sample is at a set value, which is suitable for cutting tests.

[0041] In some embodiments, the second clamping structure 32 may be a pneumatic clamp, the driving structure 33 may be an electric cylinder, and the bracket 31 may also be called an electric cylinder bracket.

[0042] In some embodiments, the drive structure 33 is configured to adjust the output tension based on the tensile force value of the sample collected by the first sensor 12, and stop adjusting the tension when the output tension reaches a set value, which is determined according to the width of the sample. In one example, the wider the width of the sample filament bundle, the larger the set value of the tension output by the drive structure 33.

[0043] In some embodiments, the set value may also be referred to as the target load value. For example, when the filament width is 2.32 mm, the target load value is 5 N.

[0044] In one example, the electric cylinder bracket of the third clamp 3 is connected to the square aluminum profile (mounting base 6) by screws. The electric cylinder is connected to the electric cylinder bracket by screws and connected to the pneumatic clamp of the third clamp 3 by a connector. One end of the sample is clamped by the pneumatic clamp of the first clamp 1 and the other end is clamped by the pneumatic clamp of the third clamp 3. The two pneumatic clamps are controlled by a dedicated foot switch to clamp or release the sample. The loading device 5 controls the movement of the electric cylinder by a set value and collects the tensile force value of the sample by the first sensor 12 of the first clamp 1. The testing machine adjusts the electric cylinder of the third clamp 3 according to the tensile force value collected by the first sensor 12 to control the tensile force of the sample to reach the set value, while ensuring that the axial clamping force of the sample after installation remains consistent during the test.

[0045] In some embodiments, such as Figure 6 As shown, the second fixture 2 includes two sliding supports 21 and a base 22. The two sliding supports 21 are slidably mounted on the base 22, which is mounted on the mounting base 6. The two sliding supports 21 are used to place the sample, and the position of the two sliding supports 21 is adjusted according to the length of the test section of the sample so that the distance between the two sliding supports 21 is consistent with the length of the test section of the sample. After the position of the two sliding supports 21 is determined, the two sliding supports 21 are fixed on the base 22 to limit the length of the test section of the sample.

[0046] In one example, the base 22 may have a T-slot 221 inside to facilitate the sliding of the two sliding supports 21. For example, the T-slot includes a groove body aligned with the extension direction of the sample, and the bottom of the sliding support 21 may have a protrusion with the shape of the groove body, so that the protrusion and the groove body form a sliding fit, allowing the two sliding supports 21 to slide in the same or opposite directions on the groove body. After the two sliding supports 21 have slid to the designated position, they can be fixed by a nut 222, such as by rotating the nut to make it contact the bottom or bottom wall of the groove body of the base 22, thereby fixing the sliding supports 21 to the base 22.

[0047] In some embodiments, such as Figure 7As shown, the bottoms of the two sliding supports 21 can be respectively provided with limiting grooves 211, and the base 22 can be provided with limiting components 223. The limiting grooves at the bottom of the sliding supports 21 and the limiting components on the base 22 cooperate and contact each other to guide and limit the sliding supports 21, so as to realize the adjustment of the distance between the two sliding supports 21. In one example, the limiting component can be a stop block, which can also be called a support stop block.

[0048] In some embodiments, such as Figure 8 As shown, the two sliding supports 21 are provided with positioning grooves 212, which can also be called positioning steps. The size of the positioning grooves 212 is adapted to the size of the reinforcing sheet on the sample.

[0049] In some embodiments, the base 22 is provided with a scale value to measure the distance between the two sliding supports 21, so that the distance is consistent with the length of the test section of the sample.

[0050] In some embodiments, such as Figure 6 As shown, the second clamp 2 also includes a screw drive 23 and two rotatable clamping components 24. The screw drive 23 is mounted on the base 22 and is connected to the two sliding supports 21. Through the screw drive 23, the distance between the two sliding supports 21 can be adjusted according to the position of the two sliding supports 21 and the length of the test section of the sample, so that the distance is consistent with the length of the test section of the sample. The two rotatable clamping components 24 are movably connected to the two sliding supports 21 respectively and are used to clamp the sample. When the sample is not clamped, the two rotatable clamping components 24 are rotated so that their clamping parts face upward. During the clamping process, the two rotatable clamping components 24 are rotated from top to bottom to clamp the sample.

[0051] In some embodiments, the screw drive 23 can be installed at either end of the base 22. Alternatively, one screw drive 23 can be installed at each end of the base 22.

[0052] In some embodiments, the two rotatable clamping structures 24 can be connected to the two sliding supports 21 respectively via connectors 242. In one example, the connector used to connect the rotatable clamping structures 24 and the sliding supports 21 can be a pin.

[0053] In some embodiments, the rotatable clamping structure 24 may also be referred to as a rotatable clamping block.

[0054] In one example, during the test, the two rotatable clamping structures 24 are first rotated to the top. After adjusting the distance between the two sliding supports 21 according to their positions and the test section length of the sample, the sample is placed according to the positioning grooves 212 on the two sliding supports 21. The sample is clamped and straightened by the first clamp 1 and the third clamp 3 (the tensile force on the sample reaches the set value). Then, the two rotatable clamping structures 24 are rotated to the bottom and fixed, while ensuring that the pressure on the sample is consistent.

[0055] In some embodiments, the fixing parts on the two rotatable clamping structures 24 are fixed by a fixing tool. In one example, the fixing screws on the two rotatable clamping structures 24 are turned with a torque wrench until they are fixed; the fixing screws can be hex socket head cap screws.

[0056] In some embodiments, such as Figure 5 As shown, the second clamp 2 also includes a lifting structure 25, which is mounted on the mounting base 6. The base 22 is mounted on the lifting structure 55. The height of the base 22 can be adjusted by the lifting structure 55 to ensure that the sample is kept horizontal when clamped.

[0057] In some embodiments, the lifting structure 25 may be a z-axis lifting platform.

[0058] In some embodiments, such as Figure 6 As shown, elastic portions 241 are respectively installed above the two rotatable clamping members 24 to clamp or release the sample. In one example, the elastic portions 241 installed above the two rotatable clamping members 24 can be compression springs. When the fixed part is released, the elasticity of the compression springs will automatically release the sample from the two rotatable clamping members 24.

[0059] In some embodiments, the loading device 5 includes a second sensor 52, such as Figure 9 As shown, the cutting assembly 4 includes a first connecting part 41, a cutting member 42, and a fixing member 43. The second sensor 52 is a sensor that collects the cutting force value when the sample is cut. The first connecting part 41 of the cutting assembly 4 is connected to the second connecting part of the second sensor 52, and the cutting member 42 is connected to the first connecting part 41, so that the second sensor 52 can collect the cutting force value applied to the sample by the cutting member 42. The cutting member 42 is used to cut the test section of the sample, and the fixing member 43 is used to fix the first connecting part 41 and the cutting member 42.

[0060] In some embodiments, the first connecting part 41 may be a connector, and the second connecting part of the second sensor 52 may be a sensor connector. The first connecting part 41 and the second connecting part of the second sensor 52 are fixed together by a fixing part. In one example, the fixing part that fixes the first connecting part 41 and the second connecting part of the second sensor 52 may be a pin-locking nut.

[0061] In some embodiments, the cutting member 42 may be a cutting tool. In one example, the cutting tool may be an imported engraving tool that meets the requirements of the tool holder length, so as to ensure sufficient space when cutting the sample and avoid unnecessary damage to the loading device 5.

[0062] In some embodiments, the fixing member 43 may be a locking screw.

[0063] In one example, the handle of the cutting member 4 is connected to the first connecting part 41 via a pin hole and locked with a locking screw.

[0064] This embodiment provides a testing method, applied to the above embodiments, such as... Figure 10 As shown, the method includes: Step S110: Adjust the position of the second fixture according to the length of the test section of the sample.

[0065] In some embodiments, the distance between the two sliding supports 21 of the second clamp 2 is adjusted by the screw drive 23 on the second clamp 2 and the scale set on the base 22, so that the distance is the same as the length of the test section of the sample.

[0066] Step S120: Place the sample on the second clamp, and control the first clamp and the third clamp to move away from each other through the loading device to hold the sample.

[0067] In some embodiments, after adjusting the position of the second clamp 2, the sample is placed on the second clamp 2 according to the reinforcing plates at both ends of the sample test section and the positioning grooves on the two sliding supports 21 of the second clamp 2. The first clamp 1 and the third clamp 3 are controlled to clamp the two ends of the sample. The third clamp 3 is moved by the loading device 5, so that the first clamp 1 and the third clamp 3 move away from each other and clamp the sample with a certain tensile force. During the movement of the third clamp 3, the first sensor 12 of the first clamp 1 collects the value of the lateral tensile force on the sample. Based on the lateral tensile force value collected by the loading device 5 and the first sensor 12, the drive structure 33 of the third clamp 3 is adjusted to control the tensile force on the sample to reach the set value.

[0068] Step S130: Control the cutting component to move downwards via the loading device to cut the test segment of the sample.

[0069] In some embodiments, after the sample is clamped, the cutting assembly 4 is controlled by the loading device 5 to move downward at a set speed to cut the test segment of the sample until the test segment of the sample is completely cut.

[0070] In one example, the initial peak resistance that the cutting component 4 needs to overcome when it first cuts into the sample is the inlet force. The inlet force of the cutting component 4 is set between 0.3-1N, and the speed is set between 1-10mm / min. The inlet force is a preset force threshold. The second sensor 52 of the loading device 5 controls the cutting component 4 to cut downwards to reach the inlet force.

[0071] Step S140: Using a loading device, collect the maximum cutting force value when the sample is completely cut, and determine the brittle fracture strength per unit width of the sample based on the maximum cutting force value.

[0072] In some embodiments, the maximum cutting force value when the sample is completely cut is acquired by the second sensor 52 on the loading device 5. The brittle fracture strength per unit width of the sample is determined based on the maximum cutting force value and the formula for calculating the brittle fracture strength per unit width. The formula for calculating the brittle fracture strength per unit width is as follows: In the formula This refers to the brittle fracture strength per unit width, expressed in N / mm. This is the maximum cutting force (brittle fracture strength), expressed in Newton-hours (N). The width of the sample filament bundle is in mm.

[0073] In some embodiments, before clamping the sample, the filament width of the sample needs to be measured. The sample is then laid flat and naturally unfolded. The filament width of the sample is measured using a vernier caliper or an optical dimension measuring instrument. ).

[0074] In some embodiments, after the test is completed, the fracture mode of the sample needs to be analyzed. If necessary, a magnifying glass or microscope can be used to observe the fracture surface. The fracture must occur at the force application position of the cutting component 4, the fracture end must be flat and without plastic deformation, i.e., it must be a brittle fracture, and all the filaments of the sample must be completely cut. It is necessary to check whether the clamping position of the reinforcing sheet on the sample has slipped. If the fracture is not at the force application position of the cutting component 4, or the fracture end is not a brittle fracture, or the sample is not completely fractured, or the position of the reinforcing sheet has slipped, the test data is invalid.

[0075] In some embodiments, to achieve standardized sample preparation of carbon fiber tows, ensure sample consistency, and improve sample preparation efficiency, sample preparation fixtures that meet the requirements can be designed. For example... Figure 11As shown, the sample preparation fixture includes a platform 71, a pressure member 72, a pressure plate 73, and a counterweight 74. The platform 71, which can be called the bonding platform, is used to place the carbon fiber tow sample 75 and the bonding reinforcement sheet. The pressure member 72, the pressure plate 73, and the counterweight 74 cooperate with each other to fix the carbon fiber tow sample 75. In one example, the pressure member 72 can be a clamping nut, the pressure plate 73 can be a kraft paper pressure plate, and the counterweight 74 can be a weight or a copper rod.

[0076] In some embodiments, the sample preparation fixture can simultaneously prepare at least 6 test segments with a length between 1 and 3 mm. The bonding platform of the fixture is machined with grooves that fit with the reinforcing sheet of the sample for positioning the reinforcing sheet. The bonding platform of the fixture is provided with a groove width that matches the carbon fiber tow sample. The bonding platform of the fixture can be designed according to the width requirements of different carbon fiber tow samples. One end of the carbon fiber tow sample is fixed by a clamping nut, and the other end is taut by a 0.1-0.5 kg counterweight.

[0077] In some implementations, the method for preparing carbon fiber brittle fracture force test specimens using specimen preparation fixtures is as follows: The first step is to cut carbon fiber bundle samples with a length between 100-500mm. To ensure the consistency of the length of the carbon fiber bundle samples, a cutting tool with a standard scale positioning can be used for measurement. When cutting, a sharp blade or shearing tool should be used to make a quick and smooth cut in a direction perpendicular to the axial direction of the carbon fiber bundle.

[0078] The second step is to wrap one end of the cut carbon fiber bundle sample around the threaded end of the clamping nut, tighten the nut to fix it, and then pass the other end of the carbon fiber bundle sample through the copper rod connecting rod and fix it. The copper rod hangs freely, allowing the carbon fiber bundle sample to naturally unfold and lay flat in the groove of the tooling table.

[0079] The third step is to lay the carbon fiber tow sample flat on the tooling table, and then attach the reinforcing sheet to the carbon fiber tow sample. The attachment position of the reinforcing sheet is consistent with the positioning groove of the reinforcing sheet in the tooling. The length of the reinforcing sheet is between 10-30mm and the width is between 10-20mm.

[0080] The fourth step is to remove the carbon fiber bundle sample with the reinforcing sheet bonded to it from the sample preparation fixture, and cut the carbon fiber bundle sample so that at least 40 mm of carbon fiber is left at each end of the carbon fiber bundle sample to complete the sample preparation.

[0081] In one example, the carbon fiber tow sample was made of domestically produced T300 carbon fiber. The test section length of the sample on the sample preparation fixture was set to 2 mm. The entire process from sample preparation to testing the brittle fracture strength of the sample is as follows: Take a roll of T300 carbon fiber and cut six 200mm long carbon fiber bundle samples. When cutting the samples, use an imported engraving knife to cut quickly and smoothly along a direction perpendicular to the carbon fiber bundle axis. Wrap one end of the cut carbon fiber bundle sample around the threaded end of a clamping nut and tighten the nut to secure it. Pass the other end of the bundle through a copper rod connecting rod and fix it, allowing the copper rod to hang freely, allowing the bundle to naturally unfold and lay flat in the groove of the fixture table. After laying and fixing the six carbon fiber bundle samples in sequence, attach reinforcing plates to the six carbon fiber bundle samples one by one. The attachment position of the reinforcing plates should be consistent with the positioning groove of the reinforcing plates on the fixture. The length of the reinforcing plates should be 20mm and the width 15mm. Remove the glued carbon fiber bundle samples from the sample preparation fixture and trim them, leaving 40mm of carbon fiber at each end to complete the sample preparation. Place the prepared sample flat on a horizontal platform, allowing the bundle to naturally unfold, and measure the sample width with calipers. The prepared sample is mounted on the testing device and clamped. The two rotatable clamping structures 24 are rotated upwards, and the distance between the two sliding supports 21 is adjusted to 2mm. The sample is positioned according to the location of the reinforcing plate positioning groove on the sliding support 21. The sample is clamped and straightened using the first clamp 1 and the second clamp 2. The rotatable clamping structure 24 is then rotated downwards and locked. The rotatable clamping structure 24 is tightened using a torque wrench. The test parameters are set using the computer software system: the inlet force is set to 0.5N, the test span (length of the test section) to 2mm, and the test speed of the cutting component 4 to 5mm / min. The test is started, and five valid data points are obtained, as shown in the table below.

[0082] The data in the table above can effectively evaluate the carbon fiber properties of the samples in this test. The test can obtain the quantitative brittle fracture strength and brittle fracture strength per unit width of the sample, which can quantitatively and accurately evaluate the brittleness of the carbon fiber.

[0083] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "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 this disclosure. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0085] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0086] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0087] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A testing device, characterized in that, The testing device is used to test the brittle fracture strength of fiber materials. The testing device includes a first clamp, a second clamp, a third clamp, a cutting component, a loading device, and a mounting base. The first clamp, the second clamp, and the third clamp are disposed on the mounting base, the mounting base is disposed on the loading device, and the loading device is drivenly connected to the first clamp, the second clamp, the third clamp, and the cutting component. The first clamp is used to hold the first end of the sample; The second clamp is used to define the length of the test segment of the specimen; The third clamp is used to hold the second end of the sample; The cutting assembly is used to cut the test segment of the specimen; The loading device is used to drive the first clamp and the third clamp away from or towards the specimen to clamp or release the specimen, drive the second clamp to define and clamp the test segment, and drive the cutting assembly to apply a load to the specimen to cut the test segment.

2. The testing apparatus according to claim 1, characterized in that, The first fixture includes: A sliding component is mounted on the mounting base; The first sensor, with one end connected to the sliding member, is used to collect the tensile force value of the sample. A first clamping structure is connected to the other end of the first sensor and is used to clamp the first end of the sample.

3. The testing apparatus according to claim 1, characterized in that, The third clamp includes: The bracket is fixedly installed on the mounting base; The second clamping structure is movably connected to the bracket and is used to clamp the second end of the sample; A driving structure for driving the second clamping structure to move in order to provide a tensile force to the sample; or, The bracket is slidably mounted on the mounting base, the second clamping structure is fixedly connected to the bracket, and the driving structure is used to drive the bracket to move so as to provide tension to the sample.

4. The testing apparatus according to claim 3, characterized in that, The drive structure is configured to adjust the output tension based on the tensile force value of the sample collected by the first sensor, and stop adjusting the tension when the tension reaches a set value. The set value is determined based on the width of the sample.

5. The testing apparatus according to claim 1, characterized in that, The second clamp includes: Two sliding supports are used to place the sample, and the position of the sliding supports can be adjusted by sliding according to the length of the test section; A base is mounted on the mounting base, and two sliding supports are slidably mounted on the base. After the position of the sliding supports is determined, the two sliding supports are fixed on the base to limit the length of the test section of the sample.

6. The testing apparatus according to claim 5, characterized in that, The second clamp also includes: A screw drive component, mounted on the base, is connected to the two sliding supports for adjusting the distance between the two sliding supports according to the positions of the two sliding supports and the length of the test section. Two rotatable clamping components are movably connected to the two sliding supports respectively, and are used to clamp the sample; During the clamping process, the two rotatable clamping components rotate from top to bottom and clamp the sample.

7. The testing apparatus according to claim 5, characterized in that, The second clamp also includes: A lifting structure is installed on the mounting base, and the base is installed on the lifting structure. The lifting structure is used to adjust the height of the base.

8. The testing apparatus according to claim 6, characterized in that, Each of the two rotatable clamping members has an elastic portion installed above it, so that the rotatable clamping members can clamp or release the sample.

9. The testing apparatus according to claim 1, characterized in that, The loading device includes: The second sensor is used to collect the cutting force value when the sample is cut; The cutting assembly includes: The first connecting part is used to connect with the second connecting part of the second sensor; A cutting component, connected to the first connecting part, is used to cut the test segment of the sample; A fixing component is used to fix the first connecting part and the cutting component.

10. A testing method, characterized in that, The test method is performed via the test apparatus described in claims 1 to 9, and is used to test the brittle fracture strength of fiber materials. The test method includes: Adjust the position of the second clamp according to the length of the test section of the sample; The sample is placed on the second clamp, and the loading device controls the first clamp and the third clamp to move away from each other in order to hold the sample. The loading device controls the cutting assembly to move downwards, cutting the test segment of the sample; The loading device collects the maximum cutting force value when the sample is completely cut, and determines the brittle fracture strength per unit width of the sample based on the maximum cutting force value.

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