Microcrack prefabricating device and microcrack prefabricating method

Abstract

The invention relates to the field of material detection, in particular to a microcrack prefabricating device and a microcrack prefabricating method. The microcrack prefabricating device is composed of a moving assembly, a cutter assembly and a frame assembly, through cooperation of the moving assembly and the cutter assembly, the influence of vibration displacement of a cutter on the microcrack depth is reduced, microcrack preparation of a sample within a very small range (several microns) can be treated, and therefore control over quite precise is achieved, and the microcrack prefabricating device is suitable for large-scale popularization and application. And the ideal precrack state of the subsequent pure shear strain can be ensured. The cutter assembly is controlled by the height control assembly in the cutting process and when cutting is finished, closed-loop control over height adjustment of a cutting tool bit is achieved, stable operation of a cutter in cutting and after cutting is guaranteed, and surface damage of a sample is reduced. The microcrack preparation device is easy to operate, the preparation method is simple in step, and the purpose of prefabricating the microcracks at high precision can be achieved at low cost.

Description

Technical Field

[0001] The present invention relates to the field of material detection, and in particular to a micro-crack prefabrication device and a micro-crack prefabrication method. Background Art

[0002] The mechanical properties of materials play a crucial role in practical applications. Fracture toughness, among other factors, measures a material's ability to resist crack propagation. Among material fracture mechanisms, there are three common fracture modes: Type I, Type II, and Type III. Type I is a tensile mode, in which the crack surfaces separate directly. Type II is a sliding (in-plane shear) mode, in which the crack surfaces slide perpendicular to the crack front. Type III is a tearing (anti-plane shear) mode, in which the crack surfaces move relative to each other and parallel to the crack front. Type I is the most common loading type in engineering design. To simulate real-world loading conditions, standard tests such as single-edge notched tensile tests, double-edge notched tensile tests, single-edge notched three-point bending tests, and center-crack compression tests are widely used to study and evaluate a material's true fracture toughness. Pre-crack formation is a crucial step in testing a material's fracture toughness. The quality of the crack determines the accuracy and reliability of the test data. Therefore, the development of stable and reliable pre-crack methods and corresponding equipment is highly desirable.

[0003] According to different fracture toughness test standards, researchers have developed different methods and equipment for prefabricating cracks. The traditional method is to quickly prefabricate cracks by manually controlling a sharp blade. However, this method cannot accurately control the depth and width of the cracks. When the hardness of the material for prefabricating cracks is very high, manual prefabrication of cracks is very difficult, so it is very necessary to develop an automatic mechanized prefabricated crack device. For example, patent CN202010274172.3 provides a method for preparing a specimen with surface cracks, which prefabricates a protrusion on the surface of the specimen, forms a crack on the protrusion that penetrates the specimen, and finally removes the protrusion to obtain a prefabricated crack specimen. However, in the process of removing the protrusion, this technical solution is difficult to avoid causing a certain degree of damage to the surface of the specimen. At the same time, the design of the protrusion makes it difficult to control the distance that the crack penetrates into the base layer of the specimen, and cannot meet the needs of high-precision microcrack preparation. Summary of the Invention

[0004] The present invention aims to overcome the defects of the prior art microcrack manufacturing method, which is easy to cause sample surface damage, difficult to control the crack morphology and depth, and cannot meet the needs of high-precision microcrack preparation. A microcrack prefabrication device and a microcrack prefabrication method are provided.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: The present invention discloses a micro-crack prefabrication device, which is composed of a moving component, a tool component and a frame component: a moving assembly comprising a clamping device for clamping the sample and a driving device for driving the clamping device to reciprocate along a predetermined trajectory; A tool assembly comprising a cutting head for cutting a specimen to form microcracks, a pressure assembly for applying pressure to the cutting head to adjust the vertical position of the cutting head, and a height control assembly for adjusting the displacement of the cutting head, wherein the height control assembly includes a displacement sensor for detecting the position of the cutting head in real time and providing feedback to the pressure assembly, thereby achieving closed-loop control of the height adjustment of the cutting head; The frame assembly is used to fixedly connect the moving assembly and the tool assembly so that the reciprocating motion direction of the moving assembly intersects with the direction of the cutting head.

[0006] To create microcracks in a material, an external load is applied to induce stress concentration in a localized area of ​​the material. When the stress exceeds the material's fracture toughness, a crack forms at the stress concentration. Existing methods for applying external loads include static loading, which applies a static force to the specimen surface. When the local stress exceeds the material's critical fracture stress, microcracks are generated. Mechanical cutting, which primarily uses high-speed motion of a cutting tool, creates microcracks on the specimen surface. The main problem with static loading is that the energy input relies solely on the initial loading force, making it impossible to adjust the energy release rate in real time during crack propagation. Furthermore, internal defects in the material can affect the location of cracks, making it difficult to control the depth and morphology of microcracks. Existing mechanical cutting also poses a problem: high-speed tool motion can easily cause vibration or oscillation, leading to surface damage on the specimen. This can alter the specimen's microstructure and introduce residual stresses, potentially affecting subsequent testing (such as fatigue testing and mechanical properties testing), interfering with the assessment of the material's true performance. At the same time, the existing technology mainly uses the tool as the source of applied force, which makes it difficult to obtain a linear relationship between the external force and the crack depth, and thus it is difficult to control the depth of the microcracks. It is even more difficult to control other morphological characteristics of the cracks (such as the degree of crack curvature, bifurcation, surface roughness, etc.).

[0007] The present invention offers the following improvements over the prior art: First, unlike traditional methods that rely on a cutting tool to provide cutting power, the present microcrack prefabrication device utilizes the reciprocating motion of the specimen to provide cutting power. Traditional methods that rely on a cutting device to provide cutting power can cause the crack path to shift due to resonance generated by the cutting device's motion. Furthermore, due to the high inertia of the cutting device, the cutting head will continue to cut the specimen even when it is stopped, affecting crack accuracy. The present invention's microcrack prefabrication mechanism, on the other hand, relies on a moving assembly to drive the specimen in reciprocating motion. During this reciprocating motion, the specimen surface and the cutting head come into contact for a very short period of time, causing stress to accumulate rapidly in a localized area. This converts the kinetic energy of the moving assembly into energy required for crack propagation, further deepening the crack as a result of this reciprocating motion. Therefore, the present invention minimizes the disadvantages of cutting head motion during the cutting process. Furthermore, at the end of the cut, the cutting assembly is secured by the height control assembly, so even if the specimen continues to move due to inertia, the crack depth does not deepen, significantly improving the accuracy of microcrack preparation.

[0008] Second, the present invention controls the displacement of the tool through a height control component. Since most of the micro cracks are at the micron level, how to control the distance that the cutter head enters the sample is a key issue of the present invention. Therefore, the present invention sets a height control component on the tool assembly to regulate the displacement of the cutting head. The height control component runs through the entire process of sample cutting: during the cutting process, the tool assembly is exerted with a downward force by the pressure component. At this time, the height control component exerts a reverse force on the tool assembly by exerting friction and other means, causing the tool assembly to drop by a small amplitude; at the end of the cutting, the displacement sensor on the height control component detects that the cutting head has moved by a predetermined value and immediately stops applying pressure. At this time, under the action of the resistance exerted by the height control component, the position of the cutting head is immediately fixed to prevent the cutting head from continuing to drop and affecting the cutting accuracy.

[0009] Third, the present invention fixes the displacement assembly and the tool assembly on the frame assembly at the same time, ensuring that the reciprocating motion direction of the moving assembly always intersects with the direction of the cutting head, which not only ensures the stability of the device, but also can prepare cracks with different bending degrees and bifurcation directions by changing the angles of the displacement assembly and the tool assembly.

[0010] In summary, the present invention first changes the input method of cutting power, thereby avoiding the disadvantages of the motion cutting device to a large extent; secondly, the present invention realizes closed-loop control of the height adjustment of the cutting head through the height control component; finally, the present invention forms a stable integrated working environment of the displacement component and the tool component on the frame component, thereby realizing the preparation of high-precision microcracks on the specimen.

[0011] Preferably, the pressure assembly includes a pressure transmission rod and a pressure-applying device, wherein the pressure-applying device applies linear or nonlinear pressure to the cutting head via the pressure transmission rod. In practice, the applicant has found that when conventional methods such as traditional motors and hydraulics are used to apply pressure, the crack morphology is greatly affected by the precision of other equipment. For this reason, in practice, different weights of constant weight can be placed above the cutting head so that the gravity of the weights applies constant pressure to the cutting head via the pressure transmission rod. Under constant pressure, the depth of microcracks can be precisely controlled by controlling the reciprocating speed of the moving assembly or the cutting time.

[0012] As a further preference, the height control assembly further includes a resistance device for limiting the displacement range of the pressure transmission rod.

[0013] As a further preference, the resistance device is a clamping block made of elastic material, which covers the outer side of the pressure transmission rod.

[0014] Preferably, the frame assembly includes a pulley assembly for clamping the pressure transmission rod and guiding the vertical movement of the cutter assembly. During the cutting process, the cutter assembly is subject to not only resistance from the pressure and height control assembly but also lateral forces from the movement assembly, which can easily cause the cutter assembly to deflect. The pulley assembly's rotational axis is fixed to the frame assembly, and the pulley is in close contact with the pressure transmission rod to resist lateral forces and maintain stable vertical movement of the cutter assembly.

[0015] Further preferably, the pulley assembly includes a gantry plate fixed to the frame assembly, and two or more pulleys fixed to the gantry plate, such that a path is formed between the pulleys to clamp the pressure transmission rod. In practice, a switchable limit device can be added to the pulleys, such as inserting friction blocks between the multiple pulleys, or installing a brake device on the gantry plate that can engage the pulleys. When it is necessary to ensure that the tool assembly is stationary, the pulleys can be manually switched on and off to control whether they can slide.

[0016] Preferably, the driving device comprises a screw transmission mechanism and a motor, wherein the screw transmission mechanism is threadedly connected to the clamping device. By changing the power of the motor, the speed of the reciprocating motion of the moving component can be changed.

[0017] As a further preference, the driving device further includes a guide rod parallel to the screw rod, and the guide rod is connected by the sliding sleeve and fixed to the fixed frame assembly.

[0018] On the other hand, the present invention also discloses a microcrack prefabrication method using the above-mentioned microcrack prefabrication device, comprising the following steps: S1. Clamp the sample to be prepared with microcracks on a clamping device, and start the driving device to make the sample reciprocate along a predetermined trajectory; S2. Pressurizing the tool assembly through the pressure assembly to drive the cutting head to contact the sample, and adjusting the pressure based on feedback from the displacement sensor until the cutting head reaches a preset displacement value; S3. Stop pressurizing and maintain the position of the cutting head to complete the preparation of microcracks on the sample.

[0019] Preferably, in step S1, the reciprocating speed of the sample is 50~200mm / s, and in step S2, the pressure applied by the pressure component is 0.1~0.4N. Due to the large difference in physical properties between resin and ceramic, there is currently almost no microcrack preparation device that can be applied to the above materials at the same time. The applicant has found in practice that using the microcrack prefabrication device of the present invention, when the applied pressure is 0.1~0.4N, for commercial resin, 30s cutting is performed, and when the reciprocating speed of the sample is between 50~200mm / s, a good morphology of microcracks with a depth of 150~350um can be formed, and the crack depth shows a good linear relationship with the reciprocating speed and the applied pressure. Cutting ceramics for 1h in the above speed and pressure range can form good morphology of microcracks with a depth of 2.5~15um, and the crack depth shows a good linear relationship with the reciprocating speed.

[0020] Therefore, the present invention has the following beneficial effects: (1) The present invention reduces the influence of tool vibration displacement on the depth of microcracks by coordinating the moving assembly with the tool assembly, and can handle the preparation of microcracks in a very small range (a few microns) of the sample, thereby achieving quite precise control, ensuring the subsequent pure shear strain and the appearance of an ideal prefabricated crack state.

[0021] (2) The present invention realizes closed-loop control of the height adjustment of the cutting head by controlling the tool assembly during and after the cutting process through the height control assembly, thereby ensuring the stable operation of the tool during and after cutting and reducing damage to the sample surface.

[0022] (3) The microcrack preparation device of the present invention is easy to operate, and the preparation method has simple steps, which can achieve the purpose of high-precision prefabrication of microcracks at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a microcrack prefabrication device according to Example 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of the moving components of a microcrack prefabrication device according to Example 1 of the present invention.

[0025] Figure 3 This is a schematic structural diagram of a tool assembly of a microcrack prefabrication device according to Example 1 of the present invention.

[0026] Figure 4 This is a schematic diagram of the installation of a tool assembly and a frame assembly of a microcrack prefabrication device in Example 1 of the present invention.

[0027] Figure 5 This is a schematic cutting diagram of a microcrack prefabrication device according to Example 1 of the present invention.

[0028] Figure 6 This is a micrograph of the commercial resin of Example 2 of the present invention before cutting.

[0029] Figure 7 This is a micrograph of the commercial resin after cutting according to Example 2 of the present invention.

[0030] Figure 8 This is a graph showing the relationship between the depth of the commercial resin prefabricated crack and the reciprocating motion speed in Example 2 of the present invention.

[0031] Figure 9 Graph showing the relationship between the depth of prefabricated cracks in commercial resin and the applied pressure in Example 2 of the present invention.

[0032] Figure 10 This is a micrograph of the ceramic of Example 3 of the present invention before cutting.

[0033] Figure 11 This is a micrograph of the ceramic after cutting according to Example 3 of the present invention.

[0034] Figure 12 This is a relationship diagram between the depth of the ceramic prefabricated crack and the reciprocating motion speed in Example 3 of the present invention.

[0035] Figure 13 Graph showing the relationship between the depth of prefabricated cracks in ceramics and the applied pressure in Example 3 of the present invention.

[0036] In the figure: moving component 10; clamping device 11; driving device 12; screw transmission mechanism 121; motor 122; guide rod 123; tool assembly 20; cutting head 21; pressure assembly 22; pressure transmission rod 221; pressurizing device 222; height control assembly 23; displacement sensor 231; resistance device 232; frame assembly 30; pulley assembly 31; gantry plate 311; pulley 312. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further clearly and completely described below through specific examples and in conjunction with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are given, but they are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials, reagents, etc. used in the examples, unless otherwise specified, can be obtained from commercial channels. In the present invention, unless otherwise specified, the required structural components are all structural components well known to those skilled in the art or disclosed in the prior art.

[0038] Example 1: A microcrack prefabrication device, such as Figure 1 As shown, it mainly includes three parts. The first is a moving component 10 arranged on a horizontal plane. The sample that needs to be prepared with microcracks reciprocates in a straight line on the horizontal plane under the support of the moving component 10; the second is a vertically arranged tool component 20, which is opposite to the reciprocating motion trajectory of the moving component 10, so that the sample clamped by the moving component 10 contacts the tool component 20 at least twice in one reciprocating stroke; the third is a frame component 30 for fixing the moving component 10 and the tool component 20. The frame component 30 is made of aluminum alloy. The frame component 30 is in the shape of a "mouth" on the horizontal plane for fixing the moving component 10, and a gantry for fixing the tool component 20 extends upward from the center line of the "mouth"-shaped frame, so that the moving component 10 and the tool component 20 are relatively stable during the operation of the device.

[0039] The specific structure of the moving component 10 is as follows Figure 2 As shown, the specimen is clamped by a clamping device 11 having left and right clamping members. During use, the specimen is secured to the clamping device 11 via the left and right clamping members. Three through-holes are provided below the clamping device 11. The central through-hole is threadedly connected to a screw drive mechanism 121, while the left and right through-holes directly engage guide rods 123. Guide rods 123 are fixed to the frame assembly 30, and the distal end of the screw drive mechanism 121 is connected to a motor 122. When motor 122 is activated, the screw drive mechanism 121 transmits rotational force to the clamping device 11, which, under the restraint of guide rods 123, converts this rotational force into a horizontal force that propels the clamping device 11. Motor 122 is continuously driven in both forward and reverse directions, causing the specimen on the clamping device 11 to continuously reciprocate.

[0040] The specific structure of the tool assembly 20 is as follows: Figure 3As shown, the main part is a pressure transmission rod 221 made of aluminum alloy, with a pressure device 222 fixed on the upper end thereof, and a platform for carrying heavy objects is provided above the pressure device 222; the lower end of the pressure transmission rod 221 clamps the cutting blade 21. At the same time, a displacement sensor 231 for detecting the position of the cutting head 21 is fixed on the side of the cutting blade 21. When the displacement sensor 231 detects that the displacement reaches a predetermined value, the signal can be transmitted to the pressure assembly 22. In the middle position of the pressure transmission rod 221, there is a resistance device 232 made of rubber covering the outside of the pressure transmission rod 221, which applies a certain resistance to the movement of the tool assembly 20. The connection method between the tool assembly 20 and the frame assembly 30 is as shown in the figure. Figure 4 As shown, a pulley assembly 31 is installed on the frame assembly 30, and the pulley assembly 31 clamps the pressure transfer rod 221 through two pulleys 312 on each side. At the same time, the rotating shafts of the pulleys 312 are fixed to the gantry plate 311, and the gantry plate 311 is welded to the frame assembly 30, so that the tool assembly 20 can only move vertically under the restriction of the pulley assembly 31, and the resistance device 232 abuts against the pulley assembly 31, which can prevent the tool assembly 20 from descending.

[0041] The implementation of the above device is as follows: like Figure 5 As shown, the sample is fixed by the clamping device 11, a predetermined displacement value is input to the displacement sensor 231, and the motor 122 is turned on to make the clamping device 11 continuously reciprocate. Then, when a linear force or nonlinear force greater than the resistance generated by the resistance device 232 is applied to the pressure device 222, the cutting head 21 slowly descends until it contacts the reciprocating sample. Under the combined action of the pressure component 22 and the relative movement of the sample, the kinetic energy of the moving component 10 is converted into the energy required for crack expansion, causing the crack to continue to deepen. During this period, the pulley assembly 31 maintains the vertical state of the tool assembly 20 by clamping the pressure transmission rod 221. During this period, the lower end of the measuring column of the displacement sensor 231 contacts the moving component 10, and the tool assembly 20 continues to descend, causing the measuring column of the displacement sensor 231 to continuously shrink. At this time, the shrinkage of the measuring column of the displacement sensor 231 can be equivalent to the downward displacement of the cutting head 21, achieving accurate measurement.

[0042] When the displacement sensor 231 detects a predetermined displacement value, it transmits a signal to the pressure assembly 22 to stop applying pressure. At this time, the cutting head 21 stops moving under the action of the resistance device 232. The tool assembly 20 is manually lifted and the motor 122 is turned off to complete the prefabrication of the sample microcracks.

[0043] Example 2 Microcrack prefabrication of commercial resin was performed using the microcrack prefabrication device described in Example 1. The specific steps are as follows: S1. Pre-cut a groove on the surface of the commercial resin, clamp the resin on a clamping device so that the groove is opposite to the cutting head, and start the driving device to make the sample reciprocate along a predetermined trajectory at a speed of 150 mm / s; S2. Applying a pressure of 0.3 N to the tool assembly through the pressure assembly to drive the cutting blade to contact the resin surface in the groove, and adjusting the pressure based on the feedback of the displacement sensor until the cutting blade reaches a preset displacement value; S3, stopping the pressurization and maintaining the position of the cutting head to complete the preparation of microcracks on the commercial resin.

[0044] like Figure 6 As shown, the commercial resin surface is pre-cut with grooves, as shown in Figure 7 As shown, the microcracks generated in the commercial resin after cutting for 30 seconds. It can be seen that the crack length is 187.87um, the crack edge is clear, the morphology is intact, and there is no surface damage around the crack, which meets the requirements of subsequent experiments.

[0045] Furthermore, to verify the effects of reciprocating speed and applied pressure on the depth of microcracks on the resin, the following experiments were conducted: (1) For the commercial resin used, the pressure was set to 0.3N, the cutting time was fixed to 30s, and the experimental results of the crack depth were obtained at a reciprocating speed of 50~200 mm / s, as shown in the following figure: Figure 8 As shown, it can be seen that there is a good linear law between the reciprocating motion speed and the crack depth on the resin.

[0046] (2) For the commercial resin used, the reciprocating speed is set to 150 mm / s, the cutting time is fixed to 30 s, and the experimental results of different crack depths are obtained under the applied pressure of 0.1~0.4N, as shown in the following figure. Figure 9 As shown, it can be seen that there is a good linear relationship between the pressure applied on the resin and the crack depth.

[0047] Example 3 Microcrack prefabrication of ceramics is performed using the microcrack prefabrication device described in Example 1, and the specific steps are as follows: S1. Pre-cut a groove on the surface of the ceramic, clamp the ceramic on a clamping device so that the groove is opposite to the cutting head, start the driving device to make the sample reciprocate along a predetermined trajectory at a speed of 150 mm / s; S2. Applying a pressure of 0.3 N to the tool assembly through the pressure assembly to drive the cutting blade to contact the ceramic surface in the groove, and adjusting the pressure based on the feedback of the displacement sensor until the cutting blade reaches a preset displacement value; S3, stopping the pressurization and maintaining the position of the cutting head to complete the preparation of microcracks on the commercial resin.

[0048] like Figure 10 As shown, the ceramic surface is pre-cut with grooves, as shown in Figure 11 As shown, the microcrack state of the ceramic after cutting for 1 hour. It can be seen that the crack length is 7.22um, the crack edge is clear, the morphology is intact, and there is no obvious surface damage around the crack, which meets the requirements of subsequent experiments.

[0049] Furthermore, to verify the effects of reciprocating speed and applied pressure on the depth of microcracks on ceramics, the following experiments were conducted: (1) For the ceramics used in the experiment, the pressure was set to 0.3N, the cutting time was fixed to 1h, and the experimental results of the crack depth were obtained at a reciprocating speed of 50~200 mm / s, as shown in the following figure: Figure 12 As shown, it can be seen that there is a good linear law between the reciprocating motion speed and the crack depth on the ceramic.

[0050] (2) For the ceramics used in the experiment, the reciprocating speed is set to 150 mm / s, the cutting time is fixed to 1 h, and the experimental results of different crack depths are obtained under the applied pressure of 0.1~0.4N, as shown in the following figure: Figure 13 As shown, it can be seen that there is a good linear relationship between the pressure applied on the ceramic and the crack depth.

[0051] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A microcrack prefabrication device, characterized in that: include: A moving assembly (10) comprising a clamping device (11) for clamping a sample and a driving device (12) for driving the clamping device (11) to reciprocate along a predetermined trajectory; A tool assembly (20) includes a cutting head (21) for cutting a sample to form microcracks, a pressure assembly (22) for applying pressure to the cutting head (21) to adjust the upper and lower positions of the cutting head (21), and a height control assembly (23) for adjusting the displacement of the cutting head (21), wherein the height control assembly (23) includes a displacement sensor (231) for detecting the position of the cutting head (21) in real time and feeding back to the pressure assembly (22), thereby realizing closed-loop control of the height adjustment of the cutting head (21); A frame assembly (30) is used to fixedly connect the moving assembly (10) and the cutter assembly (20), so that the reciprocating motion direction of the moving assembly (10) intersects with the direction of the cutting head (21).

2. A microcrack prefabrication device according to claim 1, characterized in that: The pressure assembly (22) comprises a pressure transmission rod (221) and a pressure device (222), wherein the pressure device (222) applies linear or nonlinear pressure to the cutting head (21) through the pressure transmission rod (221).

3. A microcrack prefabrication device according to claim 2, characterized in that: The height control assembly (23) further includes a resistance device (232) for limiting the displacement range of the pressure transmission rod (221).

4. A microcrack prefabrication device according to claim 3, characterized in that: The resistance device (232) is a clamping block made of elastic material, which covers the outer side of the pressure transmission rod (221).

5. The microcrack prefabrication device according to claim 2, characterized in that: The frame assembly (30) includes a pulley assembly (31) for clamping the pressure transmission rod (221) and guiding the tool assembly (20) to move in a vertical direction.

6. A microcrack prefabrication device according to claim 5, characterized in that: The pulley assembly (31) includes a gantry plate (311) fixed to the frame assembly (30), and two or more pulleys (312) fixed to the gantry plate (311), so that a passage for clamping the pressure transmission rod (221) is formed between the pulleys (312).

7. The microcrack prefabrication device according to claim 1, characterized in that: The driving device (12) comprises a screw transmission mechanism (121) and a motor (122), and the screw transmission mechanism (121) is threadedly connected to the clamping device (11).

8. The microcrack prefabrication device according to claim 7, characterized in that: The driving device (12) further comprises a guide rod (123) parallel to the screw transmission mechanism (121), wherein the guide rod (123) is sleeved by the clamping device (11) and fixed to the frame assembly (30).

9. A microcrack prefabrication method using the microcrack prefabrication device according to any one of claims 1 to 8, characterized in that: The steps include: S1. Clamping a sample to be prepared with microcracks on a clamping device (11), and starting a driving device (13) to cause the sample to reciprocate along a predetermined trajectory; S2, pressurizing the tool assembly (20) through the pressure assembly (22), driving the cutting head (21) to contact the sample, and adjusting the pressure based on feedback from the displacement sensor (231) until the cutting head (21) reaches a preset displacement value; S3, stop pressurizing and maintain the position of the cutting head (21), completing the preparation of microcracks on the sample.

10. A microcrack prefabrication method according to claim 9, characterized in that: In step S1, the reciprocating speed of the sample is 50-200 mm / s, and in step S2, the pressure component (22) applies a pressure of 0.1-0.4 N.

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