A system and method for composite mode i interlaminar fracture toughness testing

Abstract

This invention relates to the field of composite material testing technology, and particularly to a system and method for testing the type I interlaminar fracture toughness of composite materials. In this system, the fixture includes an upper connecting shaft and a lower connecting shaft, an upper fixture connected to the upper connecting shaft, and a lower fixture connected to the lower connecting shaft. The upper fixture has two upwardly curved hook-shaped clamping parts, and the lower fixture has two downwardly curved hook-shaped clamping parts. Two visual detectors are symmetrically arranged on both sides of the fixture. The visual detectors are used to detect the length of cracks generated in the test specimen during the type I interlaminar fracture toughness test. A robotic arm is used to clamp the test specimen, move it to the fixture, and remove it from the fixture. The robotic arm moves the test specimen to the fixture. When the hook-shaped clamping parts are engaged with the upper loading shaft and the hook-shaped clamping parts are engaged with the lower loading shaft, a universal testing machine is used to move either the upper or lower connecting shaft to perform the type I interlaminar fracture toughness test on the test specimen.

Description

Technical Field

[0001] This invention relates to the field of composite material testing technology, and in particular to a system and method for testing the interlaminar fracture toughness of composite materials. Background Technology

[0002] The application of composite materials in aircraft offers significant advantages in reducing aircraft weight, fuel consumption, maintenance costs, and extending aircraft lifespan. However, delamination sensitivity is a major weakness of many advanced composite material structures. Understanding the interlaminar fracture impedance of composite materials is useful for composite product development and material selection. To avoid interference from human factors in test results, the testing industry is moving towards automated testing.

[0003] Traditional methods use pin-type fixtures and rely on manual scribing of the sample and visual observation for recording. This method suffers from problems such as missing data points and high data subjectivity. Furthermore, gaps exist at the pin connection, which is not conducive to uniform load application. Therefore, this method is difficult to guarantee test accuracy. Summary of the Invention

[0004] This invention provides a system and method for testing the type I interlaminar fracture toughness of composite materials, which can ensure the accuracy of the test.

[0005] In a first aspect, embodiments of the present invention provide a system for testing the type I interlaminar fracture toughness of composite materials, comprising:

[0006] Universal mechanical testing machine;

[0007] The fixture includes an upper connecting shaft and a lower connecting shaft respectively connected to the universal testing machine, an upper clamp connected to the upper connecting shaft, and a lower clamp connected to the lower connecting shaft. The upper clamp is provided with two upwardly curved upper hook-shaped clamping parts, and the lower clamp is provided with two downwardly curved lower hook-shaped clamping parts. The upper hook-shaped clamping parts are used to cover the outside of the upper loading shaft of the upper loading block fixed to the test specimen to clamp the upper loading shaft. The lower hook-shaped clamping parts are used to cover the outside of the lower loading shaft of the lower loading block fixed to the test specimen to clamp the lower loading shaft. The test specimen is made of composite material.

[0008] Two visual detectors are symmetrically arranged on both sides of the fixture. The visual detectors are used to detect the length of the crack generated in the test specimen during the Type I interlaminar fracture toughness test.

[0009] A robotic arm is used to grip the test specimen, move it to the fixture, and remove it from the fixture.

[0010] The test specimen is moved to the fixture using the robotic arm. When the upper hook-shaped clamping part is engaged with the upper loading shaft and the lower hook-shaped clamping part is engaged with the lower loading shaft, the universal mechanical testing machine is used to move the upper connecting shaft or the lower connecting shaft to perform a type I interlaminar fracture toughness test on the test specimen.

[0011] Secondly, embodiments of the present invention provide a method for testing the type I interlaminar fracture toughness of composite materials, applied to the system described in the above embodiments, the method comprising:

[0012] The robotic arm is used to horizontally move the test specimen to the fixture.

[0013] The upper hook-shaped clamping part is engaged with the upper loading shaft, and the lower hook-shaped clamping part is engaged with the lower loading shaft.

[0014] The universal mechanical testing machine is used to move the upper connecting shaft or the lower connecting shaft to perform a type I interlaminar fracture toughness test on the specimen to be tested.

[0015] After the test is completed, the test specimen is removed from the fixture using the robotic arm.

[0016] As can be seen from the above scheme, the system and method for testing the type I interlaminar fracture toughness of composite materials provided by the present invention have the following beneficial effects:

[0017] By using a robotic arm to hold the tail end of the test specimen, the loading axes of the loading blocks fixed to the test specimen (i.e., the upper loading axis of the upper loading block and the lower loading axis of the lower loading block) are placed on a fixture with an upper hook-shaped clamping part and a lower hook-shaped clamping part. Then, the robotic arm and the universal mechanical testing machine work together, and the video detector records the crack propagation at the same time. This enables automated testing of the type I interlaminar fracture toughness of composite materials, which ensures the accuracy of the test. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the structure of a system for testing the type I interlaminar fracture toughness of composite materials according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the test specimen and fixture provided in one embodiment of the present invention;

[0021] Figure 3 This is a front view of a fixture provided in one embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of a test specimen provided in one embodiment of the present invention;

[0023] Figure 5 A diagram showing the state changes of the test specimen and fixture in a method for testing the interlaminar fracture toughness of composite materials according to an embodiment of the present invention.

[0024] Figure label:

[0025] 10 - Test specimen;

[0026] 101-Loading block;

[0027] 102 - Upper loading axis;

[0028] 103-Download block;

[0029] 104 - Lower loading axis;

[0030] 1-Universal mechanical testing machine;

[0031] 2-Clamp;

[0032] 21-Upper connecting shaft;

[0033] 22-Lower connecting shaft;

[0034] 23-Upper clamp;

[0035] 231-Hook-shaped clamping part;

[0036] 24-Lower clamp;

[0037] 241-Hook-shaped clamping part;

[0038] 3-Visual detector;

[0039] 4-Robotic arm. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see Figures 1 to 4This invention provides a system for testing the type I interlaminar fracture toughness of composite materials. The system includes a universal mechanical testing machine 1, a fixture 2, two visual detectors 3, and a robotic arm 4, wherein:

[0042] The fixture 2 includes an upper connecting shaft 21 and a lower connecting shaft 22 respectively connected to the universal mechanical testing machine 1, an upper fixture 23 connected to the upper connecting shaft 21, and a lower fixture 24 connected to the lower connecting shaft 22. The upper fixture 23 is provided with two upwardly curved upper hook-shaped clamping parts 231, and the lower fixture 24 is provided with two downwardly curved lower hook-shaped clamping parts 241. The upper hook-shaped clamping parts 231 are used to cover the outside of the upper loading shaft 102 of the upper loading block 101 fixed to the test specimen 10, so as to clamp the upper loading shaft 102. The lower hook-shaped clamping parts 241 are used to cover the outside of the lower loading shaft 104 of the lower loading block 103 fixed to the test specimen 10, so as to clamp the lower loading shaft 104. The test specimen 10 is made of composite material.

[0043] Two visual detectors 3 are symmetrically arranged on both sides of the fixture. The visual detectors 3 are used to detect the length of the crack generated in the test specimen 10 during the Type I interlaminar fracture toughness test.

[0044] The robotic arm 4 is used to hold the test specimen 10, move it to the fixture, and remove it from the fixture;

[0045] The test specimen 10 is moved to the fixture using the robotic arm 4. When the upper hook-shaped clamping part 231 and the upper loading shaft 102 and the lower hook-shaped clamping part 241 and the lower loading shaft 104 are fully engaged, the upper connecting shaft 21 or the lower connecting shaft 22 is moved by the universal mechanical testing machine 1 to perform a type I interlaminar fracture toughness test on the test specimen 10.

[0046] In this embodiment, by using the robotic arm 4 to clamp the tail end of the test specimen 10, the loading shafts of the loading blocks fixed to the test specimen 10 (i.e., the upper loading shaft 102 of the upper loading block 101 and the lower loading shaft 104 of the lower loading block 103) are placed on the fixture 2 with the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241. Then, the robotic arm 4 and the universal mechanical testing machine 1 work together, and the video detector 3 records the crack propagation at the same time, thereby realizing the automated testing of the interlaminar fracture toughness of composite materials, which can ensure the test accuracy.

[0047] Specifically, the video detector 3 is used as an optical device to record and read the crack propagation length, avoiding subjective errors of the human eye; the loading axis of the loading block fixed to the test specimen 10 is placed on the fixture 2 with an upper hook-shaped clamping part 231 and a lower hook-shaped clamping part 241 (i.e., the upper loading axis 102 is concentric with the upper hook-shaped clamping part 231, and the lower loading axis 104 is concentric with the lower hook-shaped clamping part 241), which has the advantage of uniform load transmission; the automation design is integrated into the test, and the robotic arm 4 is used to replace the manual pin insertion for sample loading, improving the test efficiency.

[0048] In some implementations, the visual detector 3 faces both sides of the test specimen 10, and the accuracy of the video detector is ≥0.5mm.

[0049] In some embodiments, the upper loading block 101 and the lower loading block 103 are fixed to the upper and lower surfaces of the test specimen 10 by adhesive bonding, respectively. The upper loading shaft 102 and the upper loading block 101 can be fixed by welding, integral casting, and loading shaft with perforated loading blocks. Similarly, the lower loading shaft 104 and the lower loading block 103 can also be fixed by welding, integral casting, and loading shaft with perforated loading blocks. The test specimen 10 is an integral structure, and the specimen material is a composite material with a plastic film sandwiched in the middle layer. The clamp 2 applies tension to the upper loading shaft 102 and the lower loading shaft 104, causing cracks to gradually appear in the middle layer of the test specimen 10 (i.e., the upper and lower layers of the test specimen 10 gradually separate from one end) until the length of the crack reaches a limit value (i.e., the second preset length below), so as to perform a type I interlaminar fracture toughness test on the test specimen 10.

[0050] In one embodiment of the present invention, the outlines of the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241 are semi-circular, and the semi-circular apertures of the two are equal and the centers of the semi-circles are located on the same vertical line. This ensures that the load transmitted to the test specimen 10 is also on the same vertical line.

[0051] In one embodiment of the present invention, the vertical distance between the semicircular centers of the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241 is greater than 1.5 times the sum of the thicknesses of the upper loading block 101, the test specimen 10, and the lower loading block 103. This ensures that after the upper loading shaft 102 is placed on the upper hook-shaped clamping part 231, the test specimen 10 can be rotated, and the test specimen 10 will not interfere with the lower hook-shaped clamping part 241.

[0052] In one embodiment of the present invention, the edges of the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241 are both provided with rounded corners to avoid interference between the test specimen 10 and the lower hook-shaped clamping part 241 when rotating.

[0053] In one embodiment of the present invention, the horizontal distance between the two upper hook-shaped clamping portions 231 and the horizontal distance between the two lower hook-shaped clamping portions 241 are different, and the two upper hook-shaped clamping portions 231 can be located between the two lower hook-shaped clamping portions 241 or the two lower hook-shaped clamping portions 241 can be located between the two upper hook-shaped clamping portions 231. This can ensure that the test specimen 10 is fully stressed and help avoid interference between the test specimen 10 and the lower hook-shaped clamping portions 241 when rotating.

[0054] Furthermore, one embodiment of the present invention provides a method for testing the type I interlaminar fracture toughness of composite materials, applied to the system for testing the type I interlaminar fracture toughness mentioned in any of the above embodiments, the method comprising:

[0055] The test specimen 10 is moved horizontally to the fixture 2 using the robotic arm 4.

[0056] The upper hook-shaped clamping part 231 is engaged with the upper loading shaft 102 and the lower hook-shaped clamping part 241 is engaged with the lower loading shaft 104.

[0057] The upper connecting shaft 21 or the lower connecting shaft 22 is moved by the universal mechanical testing machine 1 to perform the type I interlaminar fracture toughness test on the specimen 10 to be tested.

[0058] After the test is completed, the test specimen 10 is removed from the fixture 2 using the robotic arm 4.

[0059] In this embodiment, by using the robotic arm 4 to clamp the tail end of the test specimen 10, the loading shafts of the loading blocks fixed to the test specimen 10 (i.e., the upper loading shaft 102 of the upper loading block 101 and the lower loading shaft 104 of the lower loading block 103) are placed on the fixture 2 with the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241. Then, the robotic arm 4 and the universal mechanical testing machine 1 work together, and the video detector 3 records the crack propagation at the same time, thereby realizing the automated testing of the interlaminar fracture toughness of composite materials, which can ensure the test accuracy.

[0060] In one embodiment of the present invention, the step of "completing the engagement of the upper hook-shaped clamping part 231 with the upper loading shaft 102 and the lower hook-shaped clamping part 241 with the lower loading shaft 104" may specifically include:

[0061] Make the distance between the upper clamp 23 and the lower clamp 24 greater than a preset distance;

[0062] The upper loading shaft 102 is placed in the upper hook-shaped clamping part 231 by the robotic arm 4 so that the upper hook-shaped clamping part 231 and the upper loading shaft 102 are engaged.

[0063] The tail end of the test specimen 10 is held by the robotic arm 4 and rotated upward around the loading shaft 102 by a preset angle, while maintaining the gripping state of the robotic arm 4.

[0064] The lower connecting shaft 22 is moved upward by the universal mechanical testing machine 1.

[0065] The tail end of the test specimen 10 is held by the robotic arm 4 and rotated downwards around the loading shaft 102 until it is horizontal.

[0066] The universal mechanical testing machine 1 drives the lower connecting shaft 22 to move downward until the lower hook-shaped clamping part 241 and the lower loading shaft 104 are engaged, and the clamping state of the robotic arm 4 is released, so that the robotic arm 4 supports the test specimen 10.

[0067] In this embodiment, the upper loading shaft 102 and the lower loading shaft 104 can be allowed to enter the fixture 2 in the above manner (i.e., they will not be interfered with by the lower fixture 24). Then, by controlling the test specimen 10 to be rotated upward by a preset angle, the lower fixture 24 is moved upward, and finally the test specimen 10 is rotated downward to a horizontal state, thereby completing the cooperation between the upper hook-shaped clamping part 231 and the upper loading shaft 102, and between the lower hook-shaped clamping part 241 and the lower loading shaft 104.

[0068] In some implementations, the preset distance can be any value between 20mm and 30mm, and is not limited here.

[0069] In some implementations, the preset angle can be any angle between 45° and 75°, and is not limited here.

[0070] In one embodiment of the present invention, the step of "using the universal testing machine 1 to move the upper connecting shaft 21 or the lower connecting shaft 22 to perform a type I interlaminar fracture toughness test on the test specimen 10" may specifically include:

[0071] The universal mechanical testing machine 1 is used to move the upper connecting shaft 21 upward or the lower connecting shaft 22 downward until the visual detector 3 detects that the crack in the specimen 10 to be tested has reached the first preset length.

[0072] The universal mechanical testing machine 1 is used to drive the upper connecting shaft 21 downward or drive the lower connecting shaft 22 upward until the load between the upper clamp 23 and the lower clamp 24 is zero.

[0073] The universal mechanical testing machine 1 is used to drive the upper connecting shaft 21 to move upward or drive the lower connecting shaft 22 to move downward. When the visual detector 3 detects that the crack of the test specimen 10 reaches a preset step length, the current load data of the universal mechanical testing machine 1 is recorded until the crack length of the test specimen 10 reaches the second preset length; wherein, the second preset length is greater than the first preset length.

[0074] In one embodiment of the present invention, the first preset length is 5mm, the preset step size is 1mm, and the second preset length is 50mm.

[0075] In one embodiment of the present invention, the step "after completing the test, the test specimen 10 is removed from the fixture 2 using the robotic arm 4" may specifically include:

[0076] After the test is completed, the upper connecting shaft 21 is moved downward or the lower connecting shaft 22 is moved upward by the universal mechanical testing machine 1 to unload the load on the test specimen 10.

[0077] After unloading is completed, the test specimen 10 is removed from the fixture 2 using the robotic arm 4.

[0078] The following is combined Figure 5 This paper introduces a method for testing the toughness of type I interlaminar fracture.

[0079] The test specimen 10 has dimensions of 330mm × 24mm × 3mm (length, width, and height). The upper loading block 101 and lower loading block 103 both have dimensions of 20mm × 24mm × 10mm (length, width, and height). The upper loading block 101 is fixed with an upper loading shaft 102, and the lower loading block 103 is fixed with a lower loading shaft 104. Before testing, the upper loading block 101 and lower loading block 103 are respectively bonded to the upper and lower surfaces of the test specimen 10 to form a modified specimen (see [reference]). Figure 4 Modify fixture 2 (see also) Figure 3 The upper connecting shaft 21 of the upper clamp 23 and the lower connecting shaft 22 of the lower clamp 24 are mounted on the universal mechanical testing machine 1. The distance between the upper clamp 23 and the lower clamp 24 is opened to 35mm (i.e., 35 > (10 + 10 + 3) * 1.5 = 34.5). The schematic diagram of the preparation work is as follows. Figure 1 As shown. The following describes the automated testing steps (dashed lines represent the original state, solid lines represent the state after the action is performed), the specific steps are as follows:

[0080] Step S1: The robotic arm 4 moves and grips the tail end of the test specimen 10, keeping it horizontal. The robotic arm 4 then adjusts the angle of the test specimen 10 to ensure that its side faces the two visual detectors 3. Figure 5 State (1);

[0081] Step S2: The robotic arm 4 moves the specimen 10 to be tested, centering the upper loading shaft 102 of the specimen 10 on the hook-shaped clamping part 231, as shown. Figure 5 (2) state;

[0082] Step S3: Keep the upper loading shaft 102 placed on the upper hook-shaped clamping part 231. The robotic arm 4 clamps the tail end of the test specimen 10 and rotates it upwards by 60° around the upper loading shaft 102. After rotation, the robotic arm 4 still maintains the clamping state. Figure 5 (3) state;

[0083] Step S4: In response to the completion information of the previous action of the robotic arm 4, the lower connecting shaft 22 of the universal mechanical testing machine 1 moves vertically upward by 30mm. Figure 5 (4) state;

[0084] Step S5: The robotic arm 4, holding the tail end of the test specimen 10, rotates downwards by 60° around the upper loading shaft 102, returning the test specimen 10 to a horizontal position. After rotation, the robotic arm 4 remains in the holding state. At this time, the center of the hook-shaped gripping part 241 and the center of the lower loading shaft 104 are on the same vertical line. Figure 5 (5) status;

[0085] Step S6: In response to the completion information of the previous action of the robotic arm 4, the lower connecting shaft 22 of the universal mechanical testing machine 1 moves vertically downward by 5mm, and then releases the robotic arm 4. At this time, the upper loading shaft 102 and the lower loading shaft 104 are hooked by the upper hook-shaped clamping part 231 and the lower hook-shaped clamping part 241 respectively (i.e., the engagement is completed). The test specimen 10 is relatively stable, but the robotic arm 4 does not move and only serves as a support point for the test. Figure 5 The (6)th state;

[0086] Step S7: The lower connecting shaft 22 continues to move downwards at a speed of 1-5 mm / min, while the vision detector 3 starts recording until the crack propagation of the test specimen 10 reaches 5 mm. Then, the lower connecting shaft 22 stops moving downwards. Figure 5 State (7);

[0087] Step S8: Maintain the test state, unload the lower connecting shaft 22 at a speed not exceeding 25 mm / min until the load is zero, then reload the lower connecting shaft 22 at a speed of 1-5 mm / min. Simultaneously, the visual detector 3 starts recording, recording load data every 1 mm of crack propagation, until the total length of the delamination from the pre-crack tip reaches 50 mm. Figure 5 Status (8);

[0088] Step S9: After the test, the main unit of the universal testing machine 1 records the test data. The lower connecting shaft 22 unloads at a speed not exceeding 25 mm / min. The robotic arm 4 re-clamps the tail end of the test specimen 10. In response to the completion information of the previous action of the robotic arm 4, the universal testing machine 1 moves the lower connecting shaft 22 vertically upward by 5 mm. Figure 5 Status (9);

[0089] Step S10: Keep the upper loading shaft 102 placed on the upper hook-shaped clamping part 231. The robotic arm 4 clamps the tail end of the test specimen 10 and rotates it upwards by 60° around the upper loading shaft 102. At this time, the lower loading shaft 104 disengages from the area of ​​the lower hook-shaped clamping part 241. After rotation, the robotic arm 4 still maintains the clamping state. Figure 5 The (10)th state;

[0090] Step S11: The lower connecting shaft 22 moves downwards by 25mm, then the robotic arm 4 clamps the test specimen 10 and disengages it from the upper hook-shaped clamping part 231. The tested specimen 10 is then placed at a fixed recovery point. Figure 5 The (11)th state.

[0091] Of course, the robotic arm 4 can also clamp the test specimen 10 into the fixture 2, and then the upper connecting shaft 21 moves upward and / or the lower connecting shaft 22 moves downward. This can also achieve the engagement of the upper loading shaft 102 and the lower loading shaft 104 connected to the test specimen 10, and then perform the Type I interlaminar fracture toughness test. That is, this method does not require rotating the test specimen 10.

[0092] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0093] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for testing the type I interlaminar fracture toughness of composite materials, characterized in that, A system for testing the type I interlaminar fracture toughness of composite materials, the system comprising: Universal mechanical testing machine (1); The clamp (2) includes an upper connecting shaft (21) and a lower connecting shaft (22) respectively connected to the universal mechanical testing machine (1), an upper clamp (23) connected to the upper connecting shaft (21), and a lower clamp (24) connected to the lower connecting shaft (22). The upper clamp (23) is provided with two upwardly curved hook-shaped clamping parts (231), and the lower clamp (24) is provided with two downwardly curved hook-shaped clamping parts (241). The holding part (231) is used to cover the outside of the upper loading shaft (102) of the upper loading block (101) fixed to the test specimen (10) to clamp the upper loading shaft (102), and the hook-shaped clamping part (241) is used to cover the outside of the lower loading shaft (104) of the lower loading block (103) fixed to the test specimen (10) to clamp the lower loading shaft (104); wherein the test specimen (10) is made of composite material; Two visual detectors (3) are symmetrically arranged on both sides of the fixture. The visual detectors (3) are used to detect the length of the crack generated in the test specimen (10) during the Type I interlaminar fracture toughness test. A robotic arm (4) is used to hold the test specimen (10) and move it to and from the fixture; The horizontal distance between the two upper hook-shaped clamping parts (231) and the horizontal distance between the two lower hook-shaped clamping parts (241) are different, and the two upper hook-shaped clamping parts (231) can be located between the two lower hook-shaped clamping parts (241) or the two lower hook-shaped clamping parts (241) can be located between the two upper hook-shaped clamping parts (231); The outlines of the upper hook-shaped clamping part (231) and the lower hook-shaped clamping part (241) are semi-circular, and the semi-circular apertures of the two are equal and the centers of the semi-circles are located on the same vertical line. The vertical distance between the semicircular centers of the upper hook-shaped clamping part (231) and the lower hook-shaped clamping part (241) is greater than 1.5 times the sum of the thicknesses of the upper loading block (101), the test specimen (10), and the lower loading block (103); The edges of the upper hook-shaped clamping part (231) and the lower hook-shaped clamping part (241) are both provided with rounded corners; The method includes: The test specimen (10) is moved horizontally to the fixture (2) using the robotic arm (4). The upper hook-shaped clamping part (231) is engaged with the upper loading shaft (102), and the lower hook-shaped clamping part (241) is engaged with the lower loading shaft (104). The upper connecting shaft (21) or the lower connecting shaft (22) is moved by the universal mechanical testing machine (1) to perform a type I interlaminar fracture toughness test on the specimen (10) to be tested. After the test is completed, the test piece (10) is removed from the fixture (2) using the robotic arm (4); The process of ensuring that the upper hook-shaped clamping part (231) engages with the upper loading shaft (102) and the lower hook-shaped clamping part (241) engages with the lower loading shaft (104) includes: The distance between the upper clamp (23) and the lower clamp (24) is made greater than a preset distance; The upper loading shaft (102) is placed in the upper hook-shaped clamping part (231) by the robotic arm (4) so ​​that the upper hook-shaped clamping part (231) and the upper loading shaft (102) are engaged. The tail end of the test specimen (10) is held by the robotic arm (4) and rotated upward by a preset angle around the upper loading axis (102), while maintaining the holding state of the robotic arm (4). The lower connecting shaft (22) is moved upward by the universal mechanical testing machine (1); The tail end of the test specimen (10) is held by the robotic arm (4) and rotated downward around the upper loading axis (102) to a horizontal state; The universal mechanical testing machine (1) drives the lower connecting shaft (22) to move downward until the lower hook-shaped clamping part (241) and the lower loading shaft (104) are engaged, and the clamping state of the mechanical arm (4) is released, so that the mechanical arm (4) supports the test specimen (10). The method of using the universal testing machine (1) to move the upper connecting shaft (21) or the lower connecting shaft (22) to perform a type I interlaminar fracture toughness test on the test specimen (10) includes: The mechanical universal testing machine (1) is used to drive the upper connecting shaft (21) to move upward or drive the lower connecting shaft (22) to move downward until the visual detector (3) detects that the crack in the test specimen (10) reaches the first preset length. The upper connecting shaft (21) is moved downward or the lower connecting shaft (22) is moved upward using the universal mechanical testing machine (1) until the load between the upper clamp (23) and the lower clamp (24) is zero. The universal mechanical testing machine (1) is used to drive the upper connecting shaft (21) to move upward or drive the lower connecting shaft (22) to move downward. When the visual detector (3) detects that the crack of the test specimen (10) reaches a preset step length, the current load data of the universal mechanical testing machine (1) is recorded until the crack length of the test specimen (10) reaches a second preset length; wherein, the second preset length is greater than the first preset length.

2. The method according to claim 1, characterized in that, The first preset length is 5mm, the preset step size is 1mm, and the second preset length is 50mm.

3. The method according to any one of claims 1-2, characterized in that, After the test is completed, the robotic arm (4) is used to remove the test specimen (10) from the fixture (2), including: After the test is completed, the upper connecting shaft (21) is moved downward or the lower connecting shaft (22) is moved upward by the universal mechanical testing machine (1) to unload the load on the test specimen (10). After unloading is completed, the test specimen (10) is removed from the fixture (2) by the robotic arm (4).

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