A vibration durability simulation test tool and test method for installation of a formed fastener

Abstract

The application discloses a vibration durability simulation test tool for installation forming fasteners and a test method, relates to the technical field of durability performance detection of fasteners, and the tool comprises a vibration support table, a sample mounting plate and a pressing plate. The tool is accurately designed to simulate the stress state and the use environment of the fasteners under actual installation working conditions, and a standardized test procedure is adopted to test and compare the vibration durability performances of various installation forming fasteners under simulated complex service environments, especially under the multi-load coupling working conditions in large equipment. The scheme can realize high-fidelity simulation of the performance of the fasteners under real working conditions, and provides a scientific basis for product reliability evaluation and improvement.

Description

Technical Field

[0001] This invention relates to the field of fastener durability testing technology, specifically to a vibration durability simulation test fixture and test method for assembled fasteners. Background Technology

[0002] The existing mature test method for the anti-loosening performance of fasteners and for comparing the anti-loosening effects of various fasteners is GJB715.3 "Fasteners Test Method - Vibration". This standard specifies the method for accelerated vibration testing of fasteners. However, this method is only applicable to various fastener systems with clamping loads and additional anti-loosening mechanisms such as cotter pins.

[0003] The test used a standard shaking table and an attached Figure 1 The test fixture generates a sinusoidal vibration with a frequency of 29-30 Hz and a full amplitude of 11.4 ± 0.4 mm. The applicability of this technique is limited by the detailed dimensions of the fixture specified in the method, and it is only applicable to threaded fasteners with a nominal diameter of 5-16 mm. In practical applications of fasteners, especially in large and complex assemblies such as aerospace, various types of assembled fasteners are widely used, such as high-performance blind rivets and single-sided mounting bolts. For example, the CR series blind rivets belong to a type of pull-out mandrel blind rivet. These blind rivets generally consist of a rivet sleeve, mandrel, locking ring, and push bushing. The push bushing is only used to complete the installation with a single-drive installation tool and falls off after installation, not remaining on the machine structure. The materials of the rivet sleeve, mandrel, and locking ring are mainly titanium alloy and stainless steel. After installation, a bulge forms near the interlayer material at the blind end of the rivet sleeve. The locking ring pushes into the conical groove of the mandrel and undergoes plastic deformation, providing a holding function. (The installation state is referenced...) Figure 2 .

[0004] During the installation and forming process, the tail end of the core rod of the pulled rivet presses against the tail end of the rivet sleeve to form a blind rivet head. Once the rivet sleeve bulges into place on the side near the interlayer, the core rod breaks at the neck groove on the rivet head side. The portion of the core rod remaining inside the rivet sleeve can continue to remain there due to friction or mechanical action, sharing the shear load with the sleeve. Because it allows for single-sided installation and riveting during part assembly, it has been widely used for connections in enclosed areas or areas with poor process accessibility. Furthermore, its excellent shear resistance, capable of withstanding large shear forces, has also made it widely used in aerospace structural connections. This type of fastener is a single-sided, one-time installation fastener, and currently there are no specific vibration durability testing techniques or standard methods for simulating and studying its vibration durability under actual installation conditions and operating environments. Summary of the Invention

[0005] The purpose of this invention is to provide a vibration durability simulation test fixture and method for assembled fasteners. Through a specifically designed fixture structure, it accurately simulates the stress state and operating environment of fasteners under actual installation conditions. A standardized test procedure is used to verify and compare the vibration durability performance of various assembled fasteners under simulated complex service environments (especially multi-load coupling conditions in large equipment). This solution can achieve high-fidelity simulation of fastener performance under real working conditions, providing a scientific basis for product reliability assessment and improvement.

[0006] This invention is achieved through the following technical solution: A vibration durability simulation test fixture for mounting shaped fasteners includes a vibration support table, a sample mounting plate, and a pressure plate; The vibration support table has a through groove in the middle, and the bottom of the through groove has a mounting hole I. The vibration support table is installed and fixed to the vibration test table through the mounting hole I and the locking device. The top surface of the vibration support table has a groove for placing the sample mounting plate, and a mounting hole II is provided on the top surface. A sandwich panel is placed on the sample mounting plate. Both the sample mounting plate and the sandwich panel are provided with guide holes for mounting the pinned sample. The thickness of the sample mounting plate is slightly greater than the height of the groove. The pressure plate has a through hole and a mounting hole III in the middle. The through hole is used to allow the sandwich panel and the pinned sample on the sample mounting plate to vibrate freely up and down in the normal direction. After the sample mounting plate is placed in the groove, the pressure plate and vibration support table are installed and fixed through mounting holes II and III and locking parts, and the sample mounting plate is pressed tightly.

[0007] Furthermore, mounting hole I is a stepped hole; mounting hole II is a threaded hole.

[0008] Furthermore, the mounting holes I and the mounting holes I are symmetrically distributed.

[0009] Furthermore, the design of the vibration support table should meet the following requirements: a. Symmetrical external structure; b. The weight configuration must be compatible with the thrust-acceleration characteristic curve of the vibration test bench; c. Total power consumption must be controlled within the rated output range of the vibration test bench.

[0010] Furthermore, the thickness of the sample mounting plate is 0.5~1mm greater than the height of the groove.

[0011] Furthermore, the vibration support platform has two through slots in the middle.

[0012] A method for simulating the vibration durability of installed shaped fasteners includes the following steps: S1. Determine the number of fastener samples based on statistical requirements, inspection objectives, and actual working parameters, and select sample mounting plates and interlayer materials that match the actual service conditions. S2. Install the sample on the sample mounting plate that simulates real service conditions according to the product process requirements. Adjust the number and specifications of the interlayer on the sample mounting plate as needed. Determine whether to perform specific processing on the sample as needed. S3. Assemble the specimen mounting plate after specimen installation onto the aforementioned tooling, and determine the vibration control method and total test time; S4. Perform a sinusoidal sweep frequency test to obtain the first-order frequency of the sample mounting plate, determine the spectrum of the random vibration test based on the first-order frequency, and perform a vibration durability test. S5. After the test is completed, inspect the specimen on the specimen mounting plate to evaluate the vibration durability performance of the specimen.

[0013] Furthermore, in step S1, the materials of the sample mounting plate and the interlayer are selected according to the actual service position of the fastener sample.

[0014] Furthermore, if the fasteners are used to simulate the service positions of composite material structures, the sample mounting plate is a composite material test plate with the same or similar structure.

[0015] Furthermore, in step S2, when a control test is required, the sample mounting plate is provided with a sandwich for at least two groups, including the test group and the control group; When it is necessary to simulate the vibration durability of fasteners after the head grinding process, the fastener samples need to undergo the head grinding process.

[0016] Furthermore, in step S3, several acceleration sensors are installed on the tooling and vibration test bench, and the test is controlled by multi-point averaging.

[0017] Furthermore, in step S4, the first-order frequency of the sample mounting plate is obtained by the sweep frequency response curve obtained by the sinusoidal sweep frequency test.

[0018] Furthermore, in step S5, when inspecting the sample, observe and record the failure status of the sample, including sample loosening, locking ring dislodgement, deformation or cracking.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: I. This invention proposes a vibration durability simulation test fixture for mounting shaped fasteners. Specifically, it develops a special fixture system adapted to various vibration test benches, designs a modular sample mounting plate to meet the installation requirements of different fasteners, and solves the problem of fixture adaptability in simulating complex working conditions.

[0020] Second, this invention establishes for the first time a standardized test method for vibration durability specifically for mounted fasteners, enabling scientific research and comparative testing of the vibration performance of various mounted fasteners, and filling the gap in systematic testing technology in this field.

[0021] Third, in this invention, a composite test method combining frequency sweep and random vibration is innovatively adopted for the vibration durability simulation test method of fastener specimens. The vibration spectrum design technology based on the first-order characteristic spectrum improves the test accuracy and realizes high-fidelity simulation of the vibration characteristics of actual working conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a conventional test fixture in the prior art.

[0023] Figure 2 This is a schematic diagram of the actual installed and formed state of the pop rivet.

[0024] Figure 3 This is a schematic diagram of the pressure plate of the tooling in this invention.

[0025] Figure 4 This is a schematic diagram of the sample mounting plate of the tooling in this invention.

[0026] Figure 5 This is a schematic diagram of the vibration support platform of the tooling in this invention.

[0027] Figure 6 This is a schematic diagram of the assembled tooling in this invention.

[0028] Figure 7 It is a random spectrum of vibration test under a single first-order characteristic frequency.

[0029] Figure 8 The random spectrum of the vibration test is not a single first-order frequency.

[0030] Figure 9 This is a schematic diagram of a pinned sample mounted on a composite material test mounting plate, where: a is the test group and b is the control group.

[0031] Figure 10 This is an enlarged view of the pinned sample mounted on the composite material test mounting plate, where: a is the test group and b is the control group.

[0032] Figure 11 This is a typical sweep frequency test result diagram of a core-pulling rivet specimen mounted on a composite material test mounting plate.

[0033] Figure 12 This is a typical control curve for random vibration testing, with a duration of 12 hours.

[0034] Figure 13 These are photos of the test site in Example 7.

[0035] Among them, 1. Vibration support table; 2. Sample mounting plate; 3. Pressure plate; 4. Vibration test table; 1.1. Through groove; 1.2. Mounting hole I; 1.3. Groove; 1.4. Mounting hole II; 2.1. Interlayer; 2.2. Guide hole; 3.1. Through hole; 3.2. Mounting hole III. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0037] Example 1 A vibration durability simulation test fixture for mounting shaped fasteners, reference Figures 3-6 The tooling includes a vibration support table 1, a sample mounting plate 2, and a pressure plate 3.

[0038] The vibration support table 1 has a through groove 1.1 in the middle, and the bottom of the through groove 1.1 has a mounting hole I 1.2. The vibration support table 1 is installed and fixed to the vibration test table 4 through the mounting hole I 1.2 and the locking member. The top surface of the vibration support table 1 has a groove 1.3 for placing the sample mounting plate 2, and a mounting hole II 1.4 is provided on the top surface. A sandwich 2.1 is placed on the sample mounting plate 2. Both the sample mounting plate 2 and the sandwich 2.1 are provided with guide holes 2.2 for mounting the pin-pulled sample, and the thickness of the sample mounting plate 2 is slightly greater than the height of the groove 1.3. The pressure plate 3 has a through hole 3.1 and a mounting hole Ⅲ 3.2 in the middle. The through hole 3.1 is used to allow the interlayer 2.1 on the sample mounting plate 2 and the pin sample to vibrate freely up and down in the normal direction. After the sample mounting plate 2 is placed in the groove 1.3, the pressure plate 3 and the vibration support table 1 are installed and fixed through the mounting hole II 1.4, the mounting hole III 3.2 and the locking parts, and press the sample mounting plate 2.

[0039] Example 2 This embodiment is a further optimization of embodiment 1, the difference being that the mounting hole I 1.2 is a stepped hole; and the mounting hole II 1.4 is a threaded hole.

[0040] Example 3 The difference between this embodiment and embodiments 1-2 is that the mounting holes I1.2 are symmetrically distributed.

[0041] Example 4 Compared with Examples 1-3, the difference in this embodiment is that the design of the vibration support platform 1 should meet the following requirements: a. Symmetrical external structure; b. The weight configuration must be compatible with the thrust-acceleration characteristic curve of vibration test bench 4; c. Total power consumption must be controlled within the rated output range of vibration test bench 4.

[0042] Example 5 The difference between this embodiment and embodiments 1-4 is that the thickness of the sample mounting plate 2 is 0.5-1mm greater than the height of the groove 1.3.

[0043] Example 6 The difference between this embodiment and embodiments 1-5 is that the vibration support platform 1 has two through slots 1.1 in the middle.

[0044] Example 7 To facilitate public understanding of the present invention, this embodiment uses a vibration durability simulation test fixture for mounting and forming fasteners with a preferred structure as an example, and further illustrates the solution in conjunction with the accompanying drawings.

[0045] A vibration durability simulation test fixture for mounting formed fasteners with a preferred structure is involved, as referenced. Figures 3-6 The tooling includes a vibration support table 1, a sample mounting plate 2, and a pressure plate 3.

[0046] In this embodiment, the vibration support platform 1 has two through grooves 1.1 in the middle. The bottom of the through grooves 1.1 and the top of the vibration support platform 1 have nine mounting holes I 1.2. The mounting holes I 1.2 are stepped holes. The vibration support platform 1 is installed and fixed to the vibration test bench 4 through the mounting holes I 1.2 and the locking device. The top surface of the vibration support platform 1 has a groove 1.3 for placing the sample mounting plate 2. The groove 1.3 is a long strip groove. The size of the groove 1.3 is just enough to accommodate the sample mounting plate 2. There are six mounting holes II 1.4 on the top surface. The mounting holes II 1.4 are threaded holes.

[0047] In this embodiment, the vibration support platform 1 is generally rectangular, and the mounting holes I1.2 are symmetrically distributed. The size and number of mounting holes I1.2 need to match the vibration test platform 4.

[0048] A sandwich 2.1 is placed on the sample mounting plate 2. Both the sample mounting plate 2 and the sandwich 2.1 are provided with guide holes 2.2 for mounting the pinned sample, and the thickness of the sample mounting plate 2 is slightly greater than the height of the groove 1.3.

[0049] The pressure plate 3 has a through hole 3.1 and a mounting hole Ⅲ 3.2 in the middle. The through hole 3.1 is used to allow the interlayer 2.1 on the sample mounting plate 2 and the pin sample to vibrate freely up and down in the normal direction.

[0050] After the sample mounting plate 2 is placed in the groove 1.3, the pressure plate 3 and the vibration support table 1 are installed and fixed through the mounting hole II 1.4, the mounting hole III 3.2 and the locking parts, and press the sample mounting plate 2 to ensure that the vibration source excitation of the vibration test table 4 is effectively transmitted to the sample mounting plate 2.

[0051] In this embodiment, the design of the vibration support platform 1 should meet the following requirements: a. Symmetrical external structure; b. The weight configuration must be compatible with the thrust-acceleration characteristic curve of vibration test bench 4; c. Total power consumption must be controlled within the rated output range of vibration test bench 4.

[0052] In this embodiment, the thickness of the sample mounting plate 2 is 0.5~1mm greater than the height of the groove 1.3.

[0053] In this embodiment, the vibration support platform 1 has two through slots 1.1 in the middle.

[0054] A method for simulating the vibration durability of installed shaped fasteners includes the following steps: Step 1: Determine the number of fastener samples based on statistical requirements, inspection objectives, and actual operating parameters, and select the sample mounting plate 2 and interlayer 2.1 materials that match the actual service conditions.

[0055] In this step, the materials of the sample mounting plate 2 and the interlayer 2.1 are selected according to the actual service position of the fastener sample, and can be metallic or composite materials. For example, for fasteners simulating the service position of composite material structures, the sample mounting plate 2 is a composite material test plate with the same or similar structure.

[0056] Step 2: Install the sample on the sample mounting plate 2, which simulates real service conditions, according to the product process requirements. Adjust the quantity and specifications of the interlayer 2.1 on the sample mounting plate 2 as needed, and determine whether to perform specific processing on the sample as needed.

[0057] In this step, when a control test is required, the sample mounting plate 2 is provided with a sandwich 2.1 for at least two groups, including the test group and the control group.

[0058] When it is necessary to simulate the vibration durability of fasteners after the head grinding process, the fastener samples need to undergo the head grinding process. Similarly, when simulating the vibration durability of fasteners under inclined sandwich installation conditions, some control samples should be installed using the same inclined sandwich material.

[0059] Step 3: Assemble the sample mounting plate 2 after the sample is installed onto the aforementioned tooling, and determine the vibration control method and the total test time.

[0060] Three acceleration sensors were installed on the tooling and vibration test bench 4, and the test was controlled by multi-point averaging.

[0061] Step 4: Conduct a sinusoidal sweep frequency test to obtain the first-order frequency of the sample mounting plate 2, determine the spectrum of the random vibration test based on the first-order frequency, and conduct a vibration durability test.

[0062] In this step, the first-order frequency of the sample mounting plate 2 is obtained through the sweep frequency response curve obtained by the sinusoidal sweep frequency test. In practical applications, the vibration magnitude (or vibration test spectrum) and vibration exposure time can be provided by the designer or user, or they can be estimated based on the actual installation position, working conditions, service environment, and lifespan of the installed fastener.

[0063] Specifically, the total duration of the vibration durability test is measured in hours and can be adjusted based on the actual service life or test requirements. Interruptions are permitted depending on equipment conditions. The vibration axis is the normal direction to the mounting plate plane. If the first-order frequency of the sample mounting plate 2 exhibits a distinct single-peak characteristic, the vibration test spectrum value will be determined using the attached... Figure 7 The random spectrum was obtained, where fx is the first-order frequency of the specimen mounting plate 2. Before the test, a frequency sweep was performed on all specimen mounting plates 2, and the first-order frequency fx of each specimen mounting plate 2 was recorded. During the vibration test... Figure 7 The random spectrum between fx-100 and fx+100 Hz was used; if the first-order frequency of the sample mounting plate 2 does not show obvious single-peak characteristics, the vibration test spectrum value was adopted. Figure 8 The random spectrum is shown, where f1 and f2 are the recommended random spectral bands covering the actual sweep frequency characteristic frequencies of the sample mounting plate 2. During the vibration test, the actual sweep frequency results are used. Figure 8 The random spectrum between f1 and f2 Hz is used.

[0064] Step 5: After the test is completed, inspect the specimen on the specimen mounting plate 2 to evaluate the vibration durability performance of the specimen.

[0065] In this step, when inspecting the sample, observe and record the failure conditions of the sample, including sample loosening, locking ring dislodgement, deformation or cracking.

[0066] The following section provides further explanation using specific samples.

[0067] Figure 9 , 10 The invention demonstrates the use of the tooling and testing methods of this invention to study and compare the vibration durability of a certain blind rivet with and without a polished head. A1 and A2 are physical images of the test results with the head polished, while B1 and B2 are physical images of the test results without polishing.

[0068] To simulate the actual installation position and working conditions of this type of blind rivet, a sample mounting plate 2 with a composite material sandwich layer 2.1 was selected. The sample mounting plate 2 is made of aluminum alloy, and the sandwich layer 2.1 between the sample mounting plate 2 and the sample is made of composite material, consisting of two parts.

[0069] The number of samples is specified by the designer or user. In this embodiment, a total of 24 samples are provided, all of which are fasteners from the same batch. They are divided into 4 groups of 6 samples each. (Refer to...) Figure 9 Two groups (a1 and a2) were the grinding treatment test groups, meaning the heads of the blind rivets were ground according to actual working conditions; the other two groups (b1 and b2) were the un-grinded groups, serving as control groups for reference. Figure 9 Or 10.

[0070] After installing the sample and interlayer 2.1 onto the sample mounting plate 2 according to the process requirements, assemble the sample mounting plate 2 onto the vibration support table 1, and then place the pressure plate 3. The pressure plate 3 and the vibration support table 1 are fixed and pressed together by mounting holes II 1.4, mounting holes III 3.2, and locking element II. The entire fixture is connected to the vibration test table 4 according to the requirements of the simulation test. (Refer to...) Figure 13 .

[0071] For the specimen mounting plate 2 with unknown characteristic frequencies, the first-order frequency of the specimen mounting plate 2 is first obtained through a frequency sweep test. Then, based on the characteristics of the first-order frequency, a suitable vibration test spectrum is selected. Figure 9 or Figure 10 The vibration test spectrum was used for the next vibration durability test. In this embodiment, the sample mounting plate 2 with composite material was subjected to a frequency sweep test, and the results were referenced... Figure 11 , Figure 11 In the middle, the purple curve is the frequency sweep test response curve, which is the curve of the sample acceleration changing with frequency as measured by the actual sensor.

[0072] Depend on Figure 11 It can be seen that the first-order frequency of the mounting sample plate including the blind rivet in this embodiment does not exhibit the expected single-peak characteristic, but rather a double-peak characteristic between 550 and 700 Hz. Therefore, subsequent selection... Figure 8 The vibration durability test was further conducted using a random spectrum of vibrations at non-single first-order frequencies.

[0073] This embodiment uses a random vibration spectrum, specifically a horizontal vibration spectrum of 550~750Hz. The actual typical random vibration test control curves obtained are shown below. Figure 12 The durability vibration time is 10 hours. Figure 12 In the middle, the black undulating curve is the random vibration test control curve, the green horizontal line is the preset initial value, which is the acceleration power density curve, and the upper and lower dashed warning lines and the red line are the termination lines. The equipment will automatically terminate when it exceeds the red line.

[0074] Finally, after the test is completed, the specimens on the specimen mounting plate 2 are inspected. The failures of the blind rivets, such as loosening of the blind rivets, dislodgement of the locking ring, deformation, and cracks, are observed and recorded. The dimensions and appearance of the blind rivets on the specimen mounting plate 2 can be inspected with the help of necessary measuring tools. The vibration durability performance of the blind rivets is evaluated based on the statistical structure.

[0075] In this embodiment, the blind rivets of the test group (with the head of the rivet treated by grinding) did not show any failures such as loosening, lock ring dislodgement, deformation, or cracking after 10 hours of horizontal vibration at 550~750Hz, thus verifying that the grinding process did not affect the durability of the blind rivet samples.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A vibration durability simulation test fixture for mounting shaped fasteners, characterized in that: It includes a vibration support table (1), a sample mounting plate (2), and a pressure plate (3); The vibration support table (1) has a through groove (1.1) in the middle, and the bottom of the through groove (1.1) has a mounting hole I (1.2). The vibration support table (1) is installed and fixed to the vibration test table (4) through the mounting hole I (1.2) and the locking member. The top surface of the vibration support table (1) has a groove (1.3) for placing the sample mounting plate (2), and a mounting hole II (1.4) is provided on the top surface. A sandwich (2.1) is placed on the sample mounting plate (2). Both the sample mounting plate (2) and the sandwich (2.1) are provided with guide holes (2.2) for mounting the pin-shaped sample. The thickness of the sample mounting plate (2) is 0.5~1mm greater than the height of the groove (1.3). The pressure plate (3) has a through hole (3.1) and a mounting hole III (3.2) in the middle. The through hole (3.1) is used to allow the interlayer (2.1) on the sample mounting plate (2) and the pin sample to vibrate freely up and down in the normal direction. After the sample mounting plate (2) is placed in the groove (1.3), the pressure plate (3) and the vibration support table (1) are installed and fixed through the mounting hole II (1.4), the mounting hole III (3.2) and the locking parts, and the sample mounting plate (2) is pressed.

2. The vibration durability simulation test fixture for mounting shaped fasteners according to claim 1, characterized in that: The mounting hole I (1.2) is a stepped hole; Mounting hole II (1.4) is a threaded hole.

3. The vibration durability simulation test fixture for mounting shaped fasteners according to claim 1, characterized in that: The multiple mounting holes I (1.2) are symmetrically distributed.

4. The vibration durability simulation test fixture for mounting shaped fasteners according to claim 1, characterized in that, The design of the vibration support table (1) should meet the following requirements: a. Symmetrical external structure; b. The weight configuration must be compatible with the thrust-acceleration characteristic curve of the vibration test bench (4); c. The total power consumption must be controlled within the rated output range of the vibration test bench (4).

5. The vibration durability simulation test fixture for mounting shaped fasteners according to claim 1, characterized in that: The vibration support table (1) has two through slots (1.1) in the middle.

6. A test method for simulating the vibration durability of a pre-formed fastener as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Determine the number of fastener samples based on statistical requirements, inspection objectives and actual working conditions, and select sample mounting plate (2) and interlayer (2.1) materials that match the actual service conditions. S2. Install the sample on the sample mounting plate (2) simulating real service conditions according to the assembly process requirements of the fastener to be tested. Adjust the quantity and specifications of the interlayer (2.1) on the sample mounting plate (2) according to the requirements. Determine whether to perform specific processing on the sample according to the requirements. S3. Assemble the specimen mounting plate (2) after the specimen is installed onto the test fixture, and determine the vibration control method and the total test time; S4. Perform a sinusoidal sweep frequency test to obtain the first-order frequency of the sample mounting plate (2), determine the spectrum of the random vibration test based on the first-order frequency, and perform a vibration durability test. S5. After the test is completed, the specimen on the specimen mounting plate (2) is inspected to evaluate the vibration durability performance of the specimen.

7. The method according to claim 6, characterized in that: In step S1, the materials of the sample mounting plate (2) and the interlayer (2.1) are selected according to the actual service position of the fastener sample.

8. The method according to claim 7, characterized in that: If the fastener is used to simulate the service position of the composite material structure, the sample mounting plate (2) shall be a composite material test plate with the same or similar structure as the matrix at the actual service position of the fastener.

9. The method according to claim 6, characterized in that: In step S2, when a control test is required, the sample mounting plate (2) is provided with a sandwich (2.1) for at least two groups, including the test group and the control group. When it is necessary to simulate the vibration durability of fasteners after the head grinding process, the fastener samples need to undergo the head grinding process.

10. The method according to claim 6, characterized in that: In step S3, several acceleration sensors are installed on the tooling and vibration test bench (4), and the test is controlled by multi-point averaging.

11. The method according to claim 6, characterized in that: In step S4, the first-order frequency of the sample mounting plate (2) is obtained by the sweep frequency response curve obtained by the sinusoidal sweep frequency test.

12. The method according to claim 6, characterized in that: In step S5, when inspecting the sample, observe and record the failure conditions of the sample. Failure conditions include sample loosening, locking ring dislodgement, deformation, or cracking.

Images