Moving coil frequency adjusting device and fatigue test method

Abstract

The invention relates to a moving coil frequency adjusting device and a fatigue test method.The moving coil frequency adjusting device comprises a dial, a solid mass block, a hollow mass block and an upper gland, the solid mass block and the hollow mass block are fixed between the upper gland and the dial, the dial is provided with a convex ring, and the convex ring is connected with the hollow mass block. Arc grooves are formed in the bottoms of the solid mass block and the hollow mass block; the convex rings are embedded in the arc grooves; the moving coil frequency adjusting device is convenient to use and can adapt to samples with different appearances, sizes and installation modes, and the test efficiency is improved; a novel experimental method is provided, and the conventional thrust limitation of the vibration table is broken through by using resonance to amplify the vibration magnitude.

Description

Technical Field

[0001] This invention belongs to the field of mass fatigue testing technology, specifically a moving coil frequency adjustment device and a fatigue testing method. Background Technology

[0002] In the field of fatigue testing, in order to subject the test sample to a high stress level, it is necessary to apply a high-level vibration environment to the sample. However, conventional electromagnetic vibration tables are limited by their own operating principle. In order to achieve a balance between magnitude and frequency, the acceleration generated by high-frequency vibration is actually smaller when the total input energy is fixed. Such test methods cannot meet the needs of large-scale fatigue testing.

[0003] The purpose of this invention is to explore a new testing method that can increase the vibration magnitude while maintaining the original vibration frequency, thereby effectively carrying out large-scale fatigue tests. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a moving coil frequency adjustment device, comprising, The device comprises a dial, a solid mass block, a hollow mass block, and an upper pressure plate. The solid mass block and the hollow mass block are fixed between the upper pressure plate and the dial. The dial is provided with a convex ring. The bottom of both the solid mass block and the hollow mass block is provided with an arc groove, and the convex ring is embedded in the arc groove.

[0006] As a preferred technical solution for a moving coil frequency adjustment device, the outer ring of the dial is provided with circumferential graduations.

[0007] As a preferred technical solution for a moving coil frequency adjustment device, the hollow mass block includes a base box and a cover, and the base box is provided with a placement cavity.

[0008] As a preferred technical solution for a moving coil frequency adjustment device, the base box is provided with a first fixing hole, and the cover is provided with a second fixing hole, with the first fixing hole and the second fixing hole being in corresponding positions.

[0009] As a preferred technical solution for a moving coil frequency adjustment device, the dial is provided with a first connecting hole, the upper pressure cover is provided with a second connecting hole, and the dial and the upper pressure cover are connected by a support rod.

[0010] As a preferred technical solution for a moving coil frequency adjustment device, the upper pressure cover is provided with an array of threaded holes along the circumferential direction, and clamping bolts are provided in the threaded holes to press and fix the upper pressure cover, and locking nuts are provided on the clamping bolts.

[0011] As a preferred technical solution for a moving coil frequency adjustment device, the dial is provided with mounting holes, the dial is connected to the moving coil through the mounting holes, and the dial and the moving coil are connected by a support column.

[0012] As a preferred technical solution for a moving coil frequency adjustment device, it further includes a vibration table, on which a moving coil is arranged, a moving coil frequency adjustment device is arranged on the moving coil, a simulated sample is arranged on the moving coil, and a data acquisition and control system is arranged above the simulated sample.

[0013] The present invention also discloses a fatigue test method based on the aforementioned moving coil frequency adjustment device, comprising: acquiring a test sample and calibrating the test sample by attaching strain gauges; To obtain the vibration level required by the stress required for the sample to be tested, a frequency sweep test is performed on the sample to determine the approximate frequency range of the sample, and a moving coil frequency adjustment device is installed. Adjusting the mass block changes its mass size and mass distribution so that the resonant frequency is close to the sample's resonant frequency; Continue to observe the vibration response, fill the hollow mass block with sand to change the overall damping and thus adjust the amplification factor so that the vibration magnitude meets the requirements, and carry out the test.

[0014] The beneficial effects of this invention are: the moving coil frequency adjustment device of this invention is easy to use and can be adapted to samples with different appearances, sizes and installation methods, thus improving the experimental efficiency; and it proposes a new experimental method that uses resonance to amplify the vibration magnitude and overcome the conventional thrust limitation of the vibration table. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the overall structure of the moving coil frequency adjustment device in this invention; Figure 2 This is a schematic diagram of the scale in this invention; Figure 3 This is an exploded structural diagram of the moving coil frequency adjustment device in this invention; Figure 4 This is a schematic diagram of the hollow mass block in this invention; Figure 5 This is a schematic diagram of the fatigue testing system of the present invention; Figure 6 This is a schematic diagram of the process structure of the fatigue realization method in this invention; Figure 7 The frequency sweep curve was adjusted before the experiment; Figure 8 The frequency sweep curve was adjusted for the experiment.

[0016] Reference numerals: 7. Solid mass block; 12. Convex ring; 22. Arc groove; 13. Circumferential scale; 8. Hollow mass block; 83. Placement cavity; 81. Base box; 82. Box cover; 84. First fixing hole; 85. Second fixing hole; 51. First connecting hole; 91. Second connecting hole; 6. Support rod; 9. Upper pressure cover; 92. Threaded hole; 11. Clamping bolt; 10. Locking nut; 52. Mounting hole; 5. Dial; 15. Support column; 1. Vibration table; 2. Moving coil frequency adjustment device; 14. Moving coil; 4. Simulated sample; 3. Data acquisition and control system. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0019] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0020] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0021] Example 1 Reference Figures 1-8This embodiment provides a moving coil frequency adjustment device, including a dial 5, a solid mass block 7, a hollow mass block 8, and an upper pressure cover 9. The solid mass block 7 and the hollow mass block 8 are fixed between the upper pressure cover 9 and the dial 5. A convex ring 12 is provided on the dial 5. An arc groove 22 is provided at the bottom of both the solid mass block 7 and the hollow mass block 8, and the convex ring 12 is embedded in the arc groove 22.

[0022] Solid mass block 7 and hollow mass block 8 are both arc-shaped mass blocks.

[0023] The outer ring of the dial 5 has a circular scale 13.

[0024] The hollow mass block 8 includes a base box 81 and a cover 82, and the base box 81 is provided with a placement cavity 83.

[0025] The bottom box 81 is provided with a first fixing hole 84, and the box cover 82 is provided with a second fixing hole 85. The positions of the first fixing hole 84 and the second fixing hole 85 are corresponding.

[0026] The bottom box 81 and the cover 82 are fixed together by bolting the first fixing hole 84 and the second fixing hole 85.

[0027] The dial 5 is provided with a first connecting hole 51, and the upper pressure cover 9 is provided with a second connecting hole 91. The dial 5 and the upper pressure cover 9 are connected by a support rod 6.

[0028] The second connecting hole 91 is arranged in pairs near the inner and outer rings of the upper pressure cover 9, and the first connecting hole 51 is also arranged in pairs near the inner and outer rings of the dial 5.

[0029] The two ends of the support rod 6 are connected through the first connecting hole 51 and the second connecting hole 91, respectively.

[0030] The upper pressure cover 9 has a series of threaded holes 92 arranged along the circumferential direction. Clamping bolts 11 are installed in the threaded holes 92 to press and fix the upper pressure cover 9. Locking nuts 10 are installed on the clamping bolts 11.

[0031] The dial 5 is provided with a mounting hole 52, and the dial 5 is connected to the moving coil 14 through the mounting hole 52. The dial 5 and the moving coil 14 are connected by a support column 15.

[0032] It also includes a vibration table 1, on which a moving coil 14 is installed, on which a moving coil frequency adjustment device 2 is installed, on which a simulated sample 4 is installed, and on which a data acquisition and control system 3 is installed above the simulated sample 4.

[0033] The working principle and mechanism of the data acquisition and control system 3 are existing technologies and will not be described in detail here.

[0034] Specifically, the fatigue testing system provided by this invention is as follows: Figure 5As shown, the system consists of four parts: 1. a vibration table, 2. a moving coil frequency adjustment device, 3. a data acquisition and control system, and 4. a simulated sample. The overall experimental strategy is as follows: the simulated sample 4 is installed on the vibration table 1, and vibration stress is applied by the vibration table. The moving coil frequency adjustment device 2 adjusts the coupling between the moving coil resonant frequency and the simulated sample 4 resonant frequency. The data acquisition and control system 3 collects and processes the vibration parameters to carry out the experiment.

[0035] The moving coil frequency adjustment device is as follows: Figure 1 As shown. The dial 5 is directly mounted on the moving coil of the vibration table 1. The entire device consists of 8 height support rods 6 with threads at both ends, connected to the dial 5 and the upper pressure cover 9 respectively. The hollow mass block 7 or the solid mass block 8 has an arc-shaped groove at the bottom, which is matched with the boss limit 12 on the dial (as shown). Figure 2 (As shown) This system, in conjunction with other components, ensures accurate positioning of the counterweight, guaranteeing consistent radial placement while allowing for arbitrary adjustment of the counterweight's position on a designated circular track. Furthermore, a ring of angle graduations 13 on the dial 5 allows for quantified angle adjustments during counterweight placement, facilitating data analysis and comparison, and enabling adjustments to the size and distribution of the counterweight throughout the device. After the counterweight is positioned, the locking nut 10 is tightened onto the clamping bolt 11, which is connected to the upper cover plate 9 via threaded holes 92. Sufficient clamping force is applied to the counterweight before tightening the locking nut to ensure the stability of the entire system.

[0036] Example 2 The fatigue testing method based on the aforementioned moving coil frequency adjustment device provided by this invention is described below: Obtain the test sample, attach strain gauges for calibration, determine the required vibration level for the stress, perform a frequency sweep test to identify the approximate frequency range, install the moving coil frequency adjustment device, adjust the mass block to change its size and distribution so that the resonant frequency is close to the sample's resonant frequency, continue to observe the vibration response, fill the hollow mass block with sand to change the overall damping and thus adjust the amplification factor so that the vibration level meets the requirements, and then conduct the test. The test procedure is as follows: Figure 6 As shown.

[0037] Down Figure 7 , Figure 8The figure shows a comparison of actual data before and after the sample resonant frequency and amplification factor were adjusted using this system. As shown in the figure, by adjusting the counterweight and mass block position of this device, the first-order resonant frequency of the original system at about 400Hz was adjusted to about 200Hz. The frequency peak at about 400Hz was effectively reduced after the adjustment. The original amplification factor Q was about 100, and the amplification factor Q at the second-order resonant frequency at 400Hz was reduced to about 20 after the adjustment, which meets the numerical requirements of the test for resonant frequency and amplification factor, thus enabling the test to be carried out effectively.

[0038] This invention proposes a novel testing method: amplifying the experimental magnitude of the test component by achieving resonance after coupling the sample with the moving coil during vibration table excitation. There are two main approaches: the first involves creating an amplification fixture to achieve resonance. However, in practice, it has been found that once the fixture is manufactured, its natural frequency is fixed, making it difficult to perfectly couple the fixture's natural frequency with the sample's natural frequency. Even if some fixtures can be frequency-adjustable by modifying their structure, it's difficult to ensure that the fixture's installation state matches the actual installation state. The second approach, as proposed in this invention, is to amplify the experimental magnitude by changing the natural frequency of the vibration table's moving coil to couple with the sample's natural frequency. This method has the following advantages: firstly, the moving coil is relatively large, allowing for greater flexibility in creating the moving coil frequency adjustment device; secondly, it does not alter the sample's installation state, ensuring the reliability of the test.

[0039] According to the formula for calculating the first-order natural frequency: Where f represents the first natural frequency, k represents the stiffness of the structure, and m represents the mass of the structure.

[0040] Based on the above formula, changing the natural frequency of the moving coil is mainly achieved by altering the overall stiffness or mass of the structure. Accordingly, this invention proposes a moving coil frequency adjustment device, which involves attaching a solid mass block or a hollow mass block filled with sand to the moving coil as follows: Figure 1 This alters the overall stiffness and mass of the system, and the weight of the sand used in filling changes the amplification factor in the damping-adjusted resonant state. Furthermore, a dial on the device allows for precise adjustment of the overall mass distribution, thereby changing the overall natural frequency.

[0041] The innovations of this invention are: 1. Proposing a novel experimental method that utilizes resonance to amplify the vibration magnitude and overcome the conventional thrust limitations of a vibration table. 2. The moving coil frequency adjustment device is easy to use and can adapt to samples with various appearances, sizes, and installation methods, thus improving experimental efficiency.

[0042] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0043] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A moving coil frequency adjustment device, characterized in that: include, The dial (5), solid mass block (7), hollow mass block (8) and upper pressure cover (9) are fixed between the upper pressure cover (9) and the dial (5). A convex ring (12) is provided on the dial (5). An arc groove (22) is provided at the bottom of both the solid mass block (7) and the hollow mass block (8). The convex ring (12) is embedded in the arc groove (22).

2. The moving coil frequency adjustment device according to claim 1, characterized in that: The outer ring of the dial (5) is provided with circumferential scale (13).

3. The moving coil frequency adjustment device according to claim 1 or 2, characterized in that: The hollow mass block (8) includes a bottom box (81) and a lid (82), and the bottom box (81) is provided with a placement cavity (83).

4. The moving coil frequency adjustment device according to claim 3, characterized in that: The bottom box (81) is provided with a first fixing hole (84), and the box cover (82) is provided with a second fixing hole (85). The first fixing hole (84) and the second fixing hole (85) are in corresponding positions.

5. The moving coil frequency adjustment device according to claim 4, characterized in that: The dial (5) is provided with a first connecting hole (51), and the upper pressure cover (9) is provided with a second connecting hole (91). The dial (5) and the upper pressure cover (9) are connected by a support rod (6).

6. The moving coil frequency adjustment device according to claim 5, characterized in that: The upper pressure cover (9) is provided with a series of threaded holes (92) along the circumferential direction. A clamping bolt (11) is provided in the threaded hole (92) to press and fix the upper pressure cover (9). A locking nut (10) is provided on the clamping bolt (11).

7. The moving coil frequency adjustment device according to claim 6, characterized in that: The dial (5) is provided with a mounting hole (52), the dial (5) is connected to the moving coil (14) through the mounting hole (52), and the dial (5) and the moving coil (14) are connected by a support (15).

8. The moving coil frequency adjustment device according to claim 7, characterized in that: It also includes a vibration table (1), on which a moving coil (14) is provided, on which a moving coil frequency adjustment device (2) is provided, on which a simulated sample (4) is provided, and on which a data acquisition and control system (3) is provided above the simulated sample (4).

9. A fatigue testing method based on the moving coil frequency adjustment device according to any one of claims 1 to 8, characterized in that: Obtain the test sample and attach strain gauges to the sample for calibration. To obtain the vibration level required by the stress required for the sample to be tested, a frequency sweep test is performed on the sample to determine the approximate frequency range of the sample, and a moving coil frequency adjustment device is installed. Adjusting the mass block changes its mass size and mass distribution so that the resonant frequency is close to the sample's resonant frequency; Continue to observe the vibration response, fill the hollow mass block with sand to change the overall damping and thus adjust the amplification factor so that the vibration magnitude meets the requirements, and carry out the test.

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