Test fixture and simulation method for compression performance of composite materials under external force coupling

Abstract

The present invention discloses a test fixture and simulation method for the compression performance of composite materials under the action of external force coupling, which belongs to the technical field of test fixtures. The test fixture includes a compression cover plate, a clamping cover plate, a clamping device, and a support base. The clamping device is composed of two upper clamping plates and two lower clamping plates. The upper and lower clamping plates are slidably connected by positioning members and positioning grooves, and the spacing can be adjusted according to the height of the sample; the front and rear clamping plates are connected by adjustable bolts, which can provide lateral force to the sample. The upper and lower clamping plates are respectively connected to the compression cover plate and the support base through fixing members, and there are guide columns and guide screws between the compression cover plate and the support base. The adjusting nut is sleeved on the guide screw that passes through the compression cover plate part, and the distance between the compression cover plate and the support base is adjusted by rotating to apply longitudinal force to the sample. The fixture can be used directly as a fixture in aging experiments, and compression performance tests can be carried out directly after carrying out simulated environmental aging.

Description

Technical Field

[0001] The present invention belongs to the technical field of testing tooling, and in particular relates to a tooling and a simulation method for testing the compression performance of composite materials under external force coupling. Background Art

[0002] Composite materials, with their advantages such as fiber orientation designability and corrosion resistance, are gradually being widely used in marine environment structures such as tidal turbine blades, hulls, pipelines, and sailboats. The use of composite materials in underwater structures can significantly reduce system weight, cost, and energy consumption, and can meet established safety requirements. However, composite components will be corroded by the coupling of seawater and external stress in seawater environments, which can cause damage to the material structure or even destruction. It is worth noting that compressive strength is one of the properties of composite materials that is difficult to accurately characterize.

[0003] In composite material aging research, particularly for carbon fiber reinforced composites, the test method specified in ASTM D5529, "Standard Test Method for Hygroscopic Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials," has become the most frequently used standard for composite material aging studies. This test standard clearly recommends specimen dimensions for aging tests and methods for calculating saturated moisture absorption. However, it lacks a reference for studying aging under actual operating conditions, such as when subjected to compressive loads. Composite components serving in seawater environments are particularly susceptible to localized external loads such as water pressure or compression, making service life assessment difficult and threatening the safety of composite structures. Therefore, there is an urgent need for test equipment that can simulate the realistic stress conditions of composite materials in seawater environments and facilitate subsequent mechanical property testing.

[0004] At the same time, the test method specified in ASTM D6641, "Compression Testing of Polymer-Based Composites Using a Combined Loading Compression Test Fixture," is the most frequently used standard for testing the compression properties of composite materials. The fixtures used in this standard impose restrictions on the length, width, and thickness of the specimens. There is a lack of recommended test fixtures and standards for compression testing of large specimens. This is especially true for specimens that undergo pre-treatment such as wet heat aging before compression testing, which requires frequent fixture changes. This not only increases test errors but also increases testing costs. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a test fixture and simulation method for the compression performance of composite materials under external force coupling. The test fixture can be used in conjunction with a hot and humid environment chamber to carry out aging tests under external load coupling, and can also be used directly as a compression performance test fixture. By clamping specimens of different sizes with an adjustable clamping device, and in conjunction with the environmental chamber, it can simulate the working conditions of composite materials under external compression loads in actual service environments, thereby solving the problem that the prior art test method for the hygroscopic performance of composite materials has a single application scenario and cannot simulate the actual application environment. At the same time, the test fixture of the present invention can simultaneously carry out compression performance tests, reduce fixture switching time, and shorten testing costs.

[0006] The specific technical solutions adopted in the present invention are as follows:

[0007] In a first aspect, the present invention provides a tool for testing the compression performance of composite materials under external force coupling, comprising a compression cover plate, a clamping cover plate, a clamping device, and a support base;

[0008] The clamping device includes two upper clamping plates and two lower clamping plates for clamping the sample to be tested; the two upper clamping plates are arranged in parallel and spaced apart, and a positioning groove for inserting a positioning piece is provided at the lower part of the upper clamping plates; the two lower clamping plates are also arranged in parallel and spaced apart, and a positioning piece is vertically fixed to the top of the lower clamping plate; the positioning piece is inserted into the corresponding positioning groove, and the positioning piece forms a sliding connection in the positioning groove, and the spacing between the upper clamping plate and the lower clamping plate is adjusted according to the height of the sample to be tested; the front upper clamping plate and the rear upper clamping plate, as well as the front lower clamping plate and the rear lower clamping plate are connected by adjustable bolts, and the spacing between the front and rear clamping plates is adjusted according to the thickness of the sample to be tested;

[0009] The top of the upper clamping plate and the bottom of the lower clamping plate are respectively connected to the clamping cover plate and the support base through fixing parts; a number of vertical guide columns and guide screws are also provided between the clamping cover plate and the support base; an external thread is provided on the upper end of the guide screw, and an internal thread matching the external thread on the upper end of the guide screw is provided in the adjusting nut, and the adjusting nut is sleeved on the part of the guide screw passing through the clamping cover plate, and the distance between the clamping cover plate and the support base is adjusted by rotating the adjusting nut; the lower surface of the support base is used as the lower plane for compression performance testing; the compression cover plate is arranged above the clamping cover plate, and the upper surface of the compression cover plate is used as the upper plane for compression performance testing.

[0010] Preferably, the fixing member includes a fixing bolt and a matching fixing nut.

[0011] Furthermore, the compression cover is provided with a plurality of cover adjustment slots and cover fixing slots for passing fixing bolts, and the cover adjustment slots are through-long holes with a certain length; the length direction of the cover adjustment slots is consistent with the spacing direction of the two upper clamping plates.

[0012] Furthermore, the support base is provided with a plurality of base fixing grooves and base adjustment grooves for passing fixing bolts, and the base adjustment grooves are through-long holes with a certain length; the length direction of the base adjustment grooves is consistent with the spacing direction of the two lower clamping plates.

[0013] Preferably, the clamping cover is provided with a through hole for passing the guide column and the guide screw; the corresponding positions of the guide column and the guide screw are provided with grooves on the support base; the bottoms of the guide column and the guide screw are provided with through holes for inserting the positioning pins; the bottoms of the guide column and the guide screw are vertically inserted into the grooves on the support base and then the positioning pins are inserted to fix the guide column, the guide screw and the support base.

[0014] Preferably, the upper clamping plate and the lower clamping plate are both made of titanium alloy or aviation aluminum alloy 6000 series material; the aviation aluminum alloy 6000 series includes 6061 aluminum, 6082 aluminum or 6013 aluminum.

[0015] Preferably, the compression cover plate includes an upper cover plate and a lower cover plate arranged in parallel and spaced apart, and the upper cover plate and the lower cover plate are connected by a cross vertical support; a lower cover plate through hole is provided on the lower cover plate for passing the guide column and the guide screw.

[0016] Furthermore, a cross groove matching the cross vertical support is provided on the upper surface of the compression cover.

[0017] Preferably, a cavity is provided in the middle portion of the upper clamping plate and the lower clamping plate to reduce weight.

[0018] In a second aspect, the present invention provides a method for simulating the compressive properties of composite materials under external force coupling using the above-mentioned test fixture, the specific steps of which are as follows:

[0019] S1: A lower clamping plate is fixedly connected to the support base through a fixing piece passing through the base fixing slot, and the spacing between the two lower clamping plates is adjusted according to the thickness of the sample to be tested; the fixing piece at the bottom of the other lower clamping plate is adjusted to the position in the base adjustment slot and then fixedly connected to the support base; the sample to be tested is placed between the two lower clamping plates, and the bottom surface of the sample to be tested is flush with the support base; according to the height of the sample to be tested, the relative position of the positioning piece on the lower clamping plate inserted into the positioning slot on the upper clamping plate is adjusted, and the spacing between the upper and lower clamping plates is adjusted so that the upper surface of the sample to be tested is flush with the upper clamping plate; the two upper clamping plates and the two lower clamping plates are respectively connected by adjustable bolts, the sample to be tested is fixed in the clamping device, and a lateral load is applied;

[0020] S2: The bottoms of the guide column and the guide screw are inserted into the grooves provided on the support base, and the guide column and the guide screw are fixed vertically to the support base by inserting the positioning pins into the through holes at the bottom of the guide column and the guide screw; the compression cover plate is passed through the top of the guide column and the guide screw and placed above the two upper clamping plates; one upper clamping plate is fixedly connected to the compression cover plate by a fixing piece passing through the cover plate fixing groove, and the fixing piece on the other upper clamping plate is adjusted to the position in the cover plate adjustment groove and then fixedly connected to the compression cover plate; the adjusting nut is sleeved on the portion of the guide screw passing through the compression cover plate, and the longitudinal load is applied to the test specimen by tightening the adjusting nut;

[0021] S3: Place the fixture holding the sample to be tested in an environmental chamber to carry out an aging test; after the aging test, remove the fixture holding the sample to be tested, and pass the compression cover plate through the guide column and the guide screw and place it above the compression cover plate;

[0022] S4: Place the test fixture holding the aged sample to be tested on the universal testing machine, make the upper surface of the compression cover contact the upper compression plane of the universal testing machine, and make the bottom surface of the support base contact the lower compression plane of the universal testing machine. Set the corresponding loading parameters and perform a compression test on the sample to be tested.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention provides a fixture for testing the compressive properties of composite materials under external force coupling. By adjusting the adjusting nut, an axial force can be applied to the specimen clamped in the clamping device, and by adjusting the fixing nuts on the upper and lower clamping plates, a lateral force can be applied to the specimen. The fixture can be used directly as a fixture in aging experiments. When used in conjunction with an environmental chamber, it can simulate the conditions in which the specimen is subjected to external compressive loads in actual environments, thereby resolving the problem that existing methods for testing the hygroscopic properties of composite materials have a single application scenario and cannot simulate actual application environments.

[0025] (2) The fixture provided by the present invention can be used directly as a fixture in aging experiments, allowing compression performance tests to be conducted directly after conducting simulated environmental aging. This reduces fixture switching time, shortens testing costs, and further improves the effectiveness of test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall tooling for testing the compression properties of composite materials under external force coupling provided in this embodiment;

[0027] Figure 2 A schematic diagram of the compression cover plate provided in this embodiment;

[0028] Figure 3 A schematic diagram showing the connection between the compression cover plate, guide post, and guide screw provided in this embodiment;

[0029] Figure 4 A top view of the compression cover provided in this embodiment;

[0030] Figure 5 A schematic diagram of the clamping device provided in this embodiment;

[0031] Figure 6 A top view of the support base provided for this embodiment;

[0032] Figure 7 A schematic diagram showing the connection between the support base, guide column, and guide screw provided in this embodiment;

[0033] In the figure: compression cover plate 1, upper cover plate 101, lower cover plate through hole 102, lower cover plate 103, cross vertical support 104, pressing cover plate 2, cover plate adjustment groove 201, cover plate fixing groove 202, fixing bolt 203, fixing nut 204, cross groove 205, clamping device 3, upper clamping plate 301, lower clamping plate 302, positioning groove 303, positioning piece 304, support base 4, positioning pin 401, base fixing groove 402, base adjustment groove 403, adjusting nut 5, guide column 6, guide screw 7. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0035] In the description of the design of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the design of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the design of the present invention.

[0036] like Figure 1 As shown in FIG. 1 , as a preferred embodiment of the present invention, this embodiment provides a test fixture for the compression performance of composite materials under external force coupling. The test fixture includes a compression cover plate 1, a clamping cover plate 2, a clamping device 3, a support base 4, an adjusting nut 5, a guide post 6, and a guide screw 7.

[0037] The clamping device 3 provided in this embodiment is as follows Figure 5 As shown. The clamping device 3 is used to clamp the sample to be tested, and includes two upper clamping plates 301 and two lower clamping plates 302. The two lower clamping plates 302 are arranged in parallel and spaced apart, and the distance between the two lower clamping plates 302 can be adjusted according to the thickness of the sample to be tested. A positioning member 304 is vertically fixed on the top of the lower clamping plate 302. The two upper clamping plates 301 are arranged in parallel and spaced apart, and a positioning groove 303 for inserting the positioning member 304 is provided at the lower part of the upper clamping plate 301. The positioning member 304 is inserted into the corresponding positioning groove 303, and the positioning member 304 forms a sliding connection in the positioning groove 303. The distance between the upper clamping plate 301 and the lower clamping plate 302 is adjusted according to the height of the sample to be tested. The front upper clamping plate 301 and the rear upper clamping plate 302 are connected by adjustable bolts, and the front lower clamping plate 302 and the rear lower clamping plate 303 are also connected by adjustable bolts. The spacing between the front and rear clamping plates can be adjusted according to the thickness of the specimen to be tested. The adjustable bolts apply a lateral force to the specimen to be tested, which is clamped between the upper clamping plate 301 and the lower clamping plate 302.

[0038] In the test fixture provided in this embodiment, the top of the upper clamping plate 301 and the bottom of the lower clamping plate 302 are connected to the compression cover plate 2 and the support base 4, respectively, via fixings. In this embodiment, the fixings are fixed bolts 203 and matching nuts 204. Several vertical guide posts 6 and guide screws 7 are also provided between the compression cover plate 2 and the support base 4.

[0039] like Figure 7 As shown, the support base 4 provided in this embodiment has grooves formed at the corresponding positions for mounting the guide posts 6 and guide screws 7. The bottoms of the guide posts 6 and guide screws 7 each have through-holes for receiving positioning pins 401. The bottoms of the guide posts 6 and guide screws 7 are vertically inserted into the grooves of the support base 4, and then the positioning pins 401 are inserted, thereby securely connecting the guide posts 6 and guide screws 7 to the support base 4.

[0040] The support base 4 is also provided with a base fixing groove 402 and a base adjustment groove 403 for connecting with the two lower clamping plates 302. The base adjustment groove 403 is a through-long hole with a certain length. The length direction of the base adjustment groove 403 is consistent with the spacing direction of the two lower clamping plates 302. Figure 6 The fixing bolt 203 at the bottom of one lower clamping plate 302 passes through the base fixing slot 402 , and the fixing bolt 203 at the bottom of the other lower clamping plate 302 can move back and forth in the base adjustment slot 403 , thereby adapting to two lower clamping plates 302 with different spacings.

[0041] like Figure 3As shown, the clamping cover plate 2 provided in this embodiment also has a number of through holes for passing through the guide columns 6 and the guide screws 7. The clamping cover plate 2 also has a cover plate adjustment groove 201 and a cover plate fixing groove 202 for connecting with the two upper clamping plates 301. The cover plate adjustment groove 201 is a through-long hole with a certain length. The length direction of the cover plate adjustment groove 201 is consistent with the spacing direction of the two upper clamping plates 301. The fixing bolt 203 on the top of one upper clamping plate 301 passes through the cover plate fixing groove 202, and the fixing bolt 203 on the top of the other upper clamping plate 301 can move back and forth in the cover plate adjustment groove 201, thereby adapting to the two upper clamping plates 301 with different spacings.

[0042] like Figure 3 As shown, an external thread is provided at the upper end of the guide screw 7, and an internal thread matching the external thread at the upper end of the guide screw 7 is provided inside the adjusting nut 5. The adjusting nut 5 is sleeved on the portion of the guide screw 7 that passes through the clamping cover plate 2. By rotating the adjusting nut 5, the distance between the clamping cover plate 2 and the support base 4 is adjusted, and a longitudinal force is applied to the sample to be tested clamped between the upper clamping plate 301 and the lower clamping plate 302.

[0043] The compression cover plate 1 provided in this embodiment includes an upper cover plate 101 and a lower cover plate 103 arranged in parallel and spaced apart. The upper cover plate 101 and the lower cover plate 103 are connected by a cross vertical support 104. Figure 2 As shown. A lower cover plate through hole 102 is provided on the lower cover plate 103 for passing the guide column 6 and the guide screw 7. A cross groove 205 matching the cross vertical support 104 is provided on the upper surface of the pressing cover plate 2. The lower cover plate 103 in the compression cover plate 1 passes through the vertically arranged guide column 6 and the guide screw 7, and is then inserted into the cross groove 205 on the upper surface of the pressing cover plate 2 through the cross vertical support 104 to fix the compression cover plate 1 on the pressing cover plate 2. The provision of the cross groove 205 can not only increase the tightness of the connection between the compression cover plate 1 and the pressing cover plate 2, but also reduce the weight of the pressing cover plate 2, thereby reducing the weight of the overall test fixture. In this embodiment, cavities are also provided in the middle parts of the upper clamping plate 301 and the lower clamping plate 302 to reduce weight.

[0044] The test fixture provided by the present invention can be directly used as a fixture in an aging experiment. After simulating environmental aging, there is no need to remove the sample and then replace it with other test fixtures to perform compression performance testing. It should be noted that when conducting an aging experiment in an environmental chamber, the compression cover plate 1 does not need to be placed on the clamping cover plate 2. Because the guide column 6 and the guide screw 7 pass through the clamping cover plate 2, the upper surface must be ensured to be a plane during the compression performance test. Therefore, after the aging experiment is completed, the compression cover plate 1 is placed on the clamping cover plate 2, so that the lower surface of the support base 4 serves as the lower plane for the compression performance test, and the upper surface of the compression cover plate 1 serves as the upper plane for the compression performance test.

[0045] Because the clamping device 3 in this embodiment is placed in an environmental chamber alongside the specimen for aging testing, it must be resistant to aging corrosion and possess sufficient rigidity to apply lateral and longitudinal forces to the specimen. Therefore, the upper and lower clamping plates 301 and 302 can be made of titanium alloy or 6000-series aviation aluminum alloy. Preferably, 6061 aluminum is used in this embodiment.

[0046] Next, this embodiment further provides a method for simulating the compression performance of composite materials under external force coupling using the above-mentioned test fixture, and the specific steps are as follows:

[0047] S1: A lower clamping plate 302 is fixedly connected to the support base 4 through a fixing piece passing through the base fixing groove 402, and the distance between the two lower clamping plates 302 is adjusted according to the thickness of the sample to be tested. After the fixing piece at the bottom of the other lower clamping plate 302 is adjusted to the position in the base adjustment groove 403, it is fixedly connected to the support base 4. The sample to be tested is placed between the two lower clamping plates 302, and the bottom surface of the sample to be tested is flush with the support base 4. According to the height of the sample to be tested, adjust the relative position of the positioning piece 304 on the lower clamping plate 302 inserted into the positioning groove 303 on the upper clamping plate 301, and adjust the distance between the upper clamping plate 301 and the lower clamping plate 302 so that the upper surface of the sample to be tested is flush with the upper clamping plate 301. The two upper clamping plates 301 and the two lower clamping plates 302 are connected respectively by adjustable bolts, the sample to be tested is fixed in the clamping device 3, and a lateral load is applied.

[0048] S2: The bottom of the guide column 6 and the guide screw 7 are inserted into the grooves provided on the support base 4, and the guide column 6 and the guide screw 7 are fixed vertically on the support base 4 by inserting the positioning pin 401 into the through hole at the bottom of the guide column 6 and the guide screw 7. The clamping cover 2 is passed through the top of the guide column 6 and the guide screw 7 and placed above the two upper clamping plates 301. One upper clamping plate 301 is fixedly connected to the clamping cover 2 through a fixing piece passing through the cover fixing groove 202, and the fixing piece on the other upper clamping plate 301 is fixedly connected to the clamping cover 2 after adjusting its position in the cover adjustment groove 201. The adjusting nut 5 is mounted on the part of the guide screw 7 that passes through the clamping cover 2, and a longitudinal load is applied to the test sample by tightening the adjusting nut 5.

[0049] S3: Place the fixture holding the test specimen in an environmental chamber to conduct an aging test. This fixture can simultaneously apply lateral and longitudinal forces to the specimen, and in conjunction with the environmental chamber, it can simulate the external loads the specimen would experience in a real-world environment. After the aging test, remove the fixture holding the test specimen, and place the compression cover plate 1 through the guide post 6 and guide screw 7 above the pressure cover plate 2.

[0050] S4: Place the test fixture holding the aged specimen to be tested on the universal testing machine. According to the method requirements of ASTM D6641 of the American Society for Testing and Materials, use a torque screwdriver to evenly adjust the torque of the eight fixing bolts connecting the upper and lower clamping plates to 2.5-3 N·m three times. Complete the installation of the compression specimen. The upper surface of the compression cover plate 1 contacts the upper compression plane of the universal testing machine, and the bottom surface of the support base 4 contacts the lower compression plane of the universal testing machine. Set the corresponding loading parameters on the universal testing machine and perform a compression test on the specimen. After the specimen is destroyed, loosen all fixing bolts, disassemble the fixture along the guide screw 7 and guide column 6, remove the specimen, and complete the specimen compression test.

[0051] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A tool for testing the compression performance of composite materials under external force coupling, characterized in that: It comprises a compression cover plate (1), a pressing cover plate (2), a clamping device (3), and a support base (4); The clamping device (3) comprises two upper clamping plates (301) and two lower clamping plates (302) for clamping the sample to be tested; the two upper clamping plates (301) are arranged in parallel and spaced apart, and the lower part of the upper clamping plates (301) is provided with a positioning groove (303) for inserting the positioning member (304); the two lower clamping plates (302) are also arranged in parallel and spaced apart, and the top of the lower clamping plates (302) is vertically fixed with a positioning member (304); the positioning member (304) is inserted into the upper clamping plates (301) and ... In the corresponding positioning groove (303), the positioning member (304) forms a sliding connection in the positioning groove (303), and the distance between the upper clamping plate (301) and the lower clamping plate (302) is adjusted according to the height of the sample to be tested; the front upper clamping plate (301) and the rear upper clamping plate (301) as well as the front lower clamping plate (302) and the rear lower clamping plate (302) are connected by adjustable bolts, and the distance between the front and rear clamping plates is adjusted according to the thickness of the sample to be tested; The top of the upper clamping plate (301) and the bottom of the lower clamping plate (302) are connected to the pressing cover plate (2) and the support base (4) respectively through fixing members; a plurality of vertical guide columns (6) and a guide screw (7) are also provided between the pressing cover plate (2) and the support base (4); an external thread is provided on the upper end of the guide screw (7); an internal thread matching the external thread on the upper end of the guide screw (7) is provided inside the adjusting nut (5); the adjusting nut (5) is sleeved on the portion of the guide screw (7) passing through the pressing cover plate (2); the spacing between the pressing cover plate (2) and the support base (4) is adjusted by rotating the adjusting nut (5); the lower surface of the support base (4) serves as a lower plane for compression performance testing; the compression cover plate (1) is provided above the pressing cover plate (2), and the upper surface of the compression cover plate (1) serves as an upper plane for compression performance testing.

2. The tool for testing the compression performance of composite materials under external force coupling according to claim 1, characterized in that: The fixing member includes a fixing bolt (203) and a matching fixing nut (204).

3. The tool for testing the compression performance of composite materials under external force coupling according to claim 2, characterized in that: The pressing cover plate (2) is provided with a plurality of cover plate adjustment slots (201) and cover plate fixing slots (202) for passing fixing bolts (203), and the cover plate adjustment slots (201) are through-long holes of a certain length; the length direction of the cover plate adjustment slots (201) is consistent with the spacing direction of the two upper clamping plates (301).

4. The tool for testing the compression performance of composite materials under external force coupling according to claim 3, characterized in that: The support base (4) is provided with a plurality of base fixing slots (402) and base adjustment slots (403) for passing fixing bolts (203), and the base adjustment slots (403) are through-long holes of a certain length; the length direction of the base adjustment slots (403) is consistent with the spacing direction of the two lower clamping plates (302).

5. The tool for testing the compression performance of composite materials under external force coupling according to claim 1, characterized in that: The pressing cover plate (2) is provided with through holes for passing the guide column (6) and the guide screw (7); the corresponding positions of the guide column (6) and the guide screw (7) are provided with grooves on the support base (4); the bottoms of the guide column (6) and the guide screw (7) are provided with through holes for inserting the positioning pin (401); the bottoms of the guide column (6) and the guide screw (7) are vertically inserted into the grooves on the support base (4) and then the positioning pin (401) is inserted, so that the guide column (6), the guide screw (7) and the support base (4) are fixedly connected.

6. The tool for testing the compression performance of composite materials under external force coupling according to claim 1, characterized in that: The upper clamping plate (301) and the lower clamping plate (302) are both made of titanium alloy or aviation aluminum alloy 6000 series material; the aviation aluminum alloy 6000 series includes 6061 aluminum, 6082 aluminum or 6013 aluminum.

7. The tool for testing the compression performance of composite materials under external force coupling according to claim 1, characterized in that: The compression cover plate (1) comprises an upper cover plate (101) and a lower cover plate (103) arranged in parallel and spaced apart. The upper cover plate (101) and the lower cover plate (103) are connected via a cross vertical support (104). The lower cover plate (103) is provided with a lower cover plate through hole (102) for passing the guide column (6) and the guide screw (7).

8. The tool for testing the compression performance of composite materials under external force coupling according to claim 7, characterized in that: The upper surface of the pressing cover plate (2) is provided with a cross groove (205) that matches the cross vertical support (104).

9. The tool for testing the compression performance of composite materials under external force coupling according to claim 1, characterized in that: The middle parts of the upper clamping plate (301) and the lower clamping plate (302) are both provided with cavities for reducing weight.

10. A method for simulating the compression performance of composite materials under external force coupling using the test fixture according to claim 4, characterized in that: The specific steps are as follows: S1: A lower clamping plate (302) is fixedly connected to the support base (4) through a fixing piece passing through the base fixing groove (402), and the spacing between the two lower clamping plates (302) is adjusted according to the thickness of the sample to be tested; the fixing piece at the bottom of the other lower clamping plate (302) is adjusted to the position in the base adjustment groove (403), and then fixedly connected to the support base (4); the sample to be tested is placed between the two lower clamping plates (302), and the bottom surface of the sample to be tested is flush with the support base (4); according to Adjust the height of the sample to be tested, adjust the relative position of the positioning piece (304) on the lower clamping plate (302) inserted into the positioning groove (303) on the upper clamping plate (301), and adjust the spacing between the upper clamping plate (301) and the lower clamping plate (302) so that the upper surface of the sample to be tested is flush with the upper clamping plate (301); connect the two upper clamping plates (301) and the two lower clamping plates (302) respectively by adjustable bolts, fix the sample to be tested in the clamping device (3), and apply a lateral load; S2: The bottoms of the guide column (6) and the guide screw (7) are inserted into the grooves provided on the support base (4), and the guide column (6) and the guide screw (7) are vertically fixed to the support base (4) by inserting the positioning pin (401) into the through holes at the bottoms of the guide column (6) and the guide screw (7); the pressing cover (2) is passed through the top of the guide column (6) and the guide screw (7) and placed on top of the two upper clamping plates (301); one upper clamping plate (301) is fixedly connected to the pressing cover (2) through the fixing piece passing through the cover fixing groove (202), and the fixing piece on the other upper clamping plate (301) is fixedly connected to the pressing cover (2) after being adjusted to the position in the cover adjustment groove (201); the adjusting nut (5) is sleeved on the portion of the guide screw (7) passing through the pressing cover (2), and a longitudinal load is applied to the test specimen by tightening the adjusting nut (5); S3: placing the fixture holding the sample to be tested in an environmental chamber to carry out an aging experiment; after the aging experiment, taking out the fixture holding the sample to be tested, passing the compression cover plate (1) through the guide column (6) and the guide screw (7) and placing it above the compression cover plate (2); S4: Place the test fixture holding the aged sample to be tested on the universal testing machine, make the upper surface of the compression cover plate (1) contact the upper compression plane of the universal testing machine, and make the bottom surface of the support base (4) contact the lower compression plane of the universal testing machine. Set the corresponding loading parameters and perform a compression test on the sample to be tested.

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