Frequency Modulation Method of Free Vibration Test System

Abstract

The present invention is applicable to the technical field of bridge structure vibration testing, and provides a frequency modulation method for a free vibration test system, the test system comprising a segment model, four first spring assemblies arranged above the four corners of the top surface of the segment model, and four second spring assemblies arranged below the four corners of the bottom surface of the segment model; the first spring assembly and the second spring assembly both comprise a turntable and a plurality of springs of different stiffnesses installed circumferentially along the turntable; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs in the first spring assembly are vertically fixed on the bottom surface of the turntable, and the springs in the second spring assembly are vertically fixed on the top surface of the turntable; the frequency modulation method comprises: determining a target angle based on a first frequency; according to the target angle, controlling the turntable to rotate the target spring to a spring working point and connect it to the segment model; the target spring is a spring of stiffness corresponding to the first frequency. The present invention can realize flexible adjustment of the frequency of the free vibration test and improve the efficiency of the test.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge structure vibration testing, and in particular relates to a frequency modulation method for a free vibration test system. Background Art

[0002] As bridges continue to develop in the direction of larger spans, their stiffness also decreases, so they are extremely susceptible to wind loads. Wind tunnel tests are the mainstream method for studying the wind resistance of bridges. Among them, free vibration tests can simulate the vibration characteristics of bridges in actual wind fields through elastic suspension devices in the system. By controlling the vibration combination of different frequencies, amplitudes, and initial phases, the dynamic response of bridges can be more accurately simulated and studied, which is crucial for understanding and predicting the behavior of bridges in actual environments.

[0003] However, the current free vibration test system usually needs to be specially built according to the frequency required by the segment model in the test. Every time the segment model is replaced or the required frequency is adjusted, the support frame of the system needs to be adjusted and the system needs to be rebuilt. For example, when an elastic suspension device is used as the vibration transposition of the system to provide the vibration frequency for the test model, each time the model is changed or the frequency is changed, the original elastic suspension device must be removed, and then the spring suspension transposition must be rebuilt according to the newly determined spring suspension position and spring parameters. The disassembly and assembly process of this test system is time-consuming and labor-intensive, resulting in low efficiency of free vibration testing. Summary of the invention

[0004] In order to overcome the problems existing in the related art, an embodiment of the present invention provides a frequency modulation method for a free vibration test system to solve the problem that the disassembly and assembly process of the current free vibration test system is time-consuming and labor-intensive, resulting in low efficiency of the free vibration test.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a frequency modulation method for a free vibration test system, wherein the free vibration test system comprises a segment model, four first spring assemblies arranged above the four corners of the top surface of the segment model, and four second spring assemblies arranged below the four corners of the bottom surface of the segment model; the first spring assembly and the second spring assembly both comprise a turntable and a plurality of springs with different stiffnesses installed circumferentially along the turntable; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs in the first spring assembly are vertically fixed to the bottom surface of the turntable, and the springs in the second spring assembly are vertically fixed to the top surface of the turntable; the method comprises:

[0007] receiving a first frequency;

[0008] determining a target angle based on the first frequency;

[0009] The turntable is controlled to rotate to the target angle so that the target spring rotates to the spring working point and is connected to the segment model; the target spring is a spring with a stiffness corresponding to the first frequency.

[0010] In combination with the first aspect, in some embodiments, the plurality of springs with different stiffnesses on the turntable are arranged at equal intervals in a clockwise or counterclockwise direction in an order of increasing stiffnesses, starting from a spring with the smallest stiffness;

[0011] The determining of the target angle based on the first frequency includes:

[0012] determining a target stiffness according to the first frequency and the mass of the segment model;

[0013] The target angle is determined based on the target stiffness and the stiffness of the initial position spring; wherein the initial position spring is a spring currently located at the spring working point.

[0014] In combination with the first aspect, in some embodiments, determining the target angle based on the target stiffness and the stiffness of the initial spring includes:

[0015] Determine the angle corresponding to the arc length between the target spring and the initial spring according to the target stiffness and the stiffness of the initial spring;

[0016] Determining the target angle based on the included angle and the rotation direction of the turntable;

[0017] Wherein, the rotation direction is a preset direction, or the rotation direction is determined based on the angle and the spring arrangement direction; the spring arrangement direction is the direction in which multiple springs on the turntable are arranged from small to large in terms of stiffness.

[0018] In combination with the first aspect, in some embodiments, the segment model includes connecting members respectively arranged at the four corners of the top surface and the four corners of the bottom surface; the spring working points of each turntable correspond to the corresponding connecting members in a one-to-one vertical direction; the first end of each spring in the turntable is fixedly connected to the turntable;

[0019] After the target spring rotates to the spring working point, each connecting piece of the segment model is detachably connected to the second end of its corresponding target spring.

[0020] In combination with the first aspect, in some embodiments, the connecting member is a magnetic connecting member; the second end of each spring is provided with an electromagnetic chuck;

[0021] The step of controlling the turntable to rotate the target angle so that the target spring rotates to the spring working point and is connected to the segment model includes:

[0022] Control the electromagnetic chuck of the spring currently located at the spring working point to cut off the power, and then control the turntable to rotate to a target angle, so as to drive the target spring to rotate to the spring working point;

[0023] When the target spring rotates to the spring working point, the electromagnetic suction cup of the target spring is controlled to be energized, and the magnetic connector of the segment model is adsorbed and connected with the target spring.

[0024] In combination with the first aspect, in some embodiments, the free vibration test system further includes a first turntable bracket and a second turntable bracket;

[0025] The first turntable bracket is used to fix the first spring assembly at a preset distance above the segment model; the top of the turntable of the first spring assembly is fixedly connected to the first turntable bracket;

[0026] The second turntable bracket is used to fix the second spring assembly at the preset distance below the segment model; the bottom of the turntable of the second spring assembly is fixedly connected to the second turntable bracket;

[0027] The first turntable bracket and the second turntable bracket are both provided with a clamping fixture;

[0028] The method further comprises:

[0029] Determining a target effective number of turns of the target spring according to the first frequency;

[0030] According to the target effective number of turns, a continuous target number of spring turns in the target spring are clamped to adjust the stiffness of the target spring to the target stiffness; wherein the target number is the difference between the original effective number of turns of the target spring and the target effective number of turns; and the target stiffness is the spring stiffness calculated based on the first frequency and the mass of the segment model.

[0031] In combination with the first aspect, in some embodiments, the clamping fixture includes a base, a telescopic rod and a horizontal pressing plate; the base is fixed to the first turntable bracket and the second turntable bracket; the telescopic rod is vertically fixed to the base; one end of the horizontal pressing plate is fixedly connected to the telescopic end of the telescopic rod, and the horizontal pressing plate is perpendicular to the telescopic rod;

[0032] The step of clamping a target number of continuous spring coils in the target spring according to the target effective number of coils comprises:

[0033] Determining the target quantity according to the target effective number of turns and the original effective number of turns of the target spring;

[0034] Determining a telescopic length based on the target quantity and the target spring wire diameter;

[0035] According to the telescopic length, the telescopic rod is controlled to extend or contract to a height between the first spring coil and the second spring coil, then the horizontal pressing plate is controlled to be inserted between the first spring coil and the second spring coil, and finally the telescopic rod is controlled to contract to clamp the target number of spring coils;

[0036] Among them, the first spring coil is the target number of spring coils starting from the first spring coil connecting the target spring and the rotating disk; the second spring coil is the spring coil adjacent to the first spring coil and away from the rotating disk.

[0037] In combination with the first aspect, in some embodiments, the clamping fixture is a hydraulic pliers, and the maximum jaw width of the hydraulic pliers is greater than a preset width; the preset width is determined based on a preset number of turns and a wire diameter of each spring in the first spring assembly.

[0038] In combination with the first aspect, in some embodiments, the free vibration test system further comprises two support rails respectively arranged below two ends of the segment model; the support rails are parallel to the wide side of the segment model;

[0039] The free vibration test system comprises four first turntable brackets and four second turntable brackets, wherein the first turntable bracket and the second turntable bracket are horizontal rods;

[0040] The free vibration test system further comprises four vertically arranged connecting rods, wherein the connecting rods are used to fix and connect a group of first turntable brackets and second turntable brackets corresponding to each other up and down to form an integrated bracket;

[0041] The second turntable bracket includes a slider arranged at the bottom; the two second turntable brackets arranged below the same end of the segment model are both slidably connected to the bracket track of this end through the slider; when the two integrated brackets at the same end of the segment model slide toward each other on the bracket track, the distance between the spring working points corresponding to the two first spring assemblies at this end of the segment model decreases; when the two integrated brackets at the same end of the segment model slide away from each other on the bracket track, the distance between the spring working points corresponding to the two first spring assemblies at this end of the segment model increases.

[0042] In combination with the first aspect, in some embodiments, the method further includes:

[0043] receiving a second frequency;

[0044] determining a target distance based on the first frequency and the second frequency;

[0045] Determine the moving distance of the integrated support according to the target distance and the initial distance; wherein the initial distance is the distance between the spring working points corresponding to the two first spring assemblies at the same end of the current segment model;

[0046] Based on the moving distance, the two integrated brackets at the same end of the segment model are controlled to move toward or away from each other along the bracket track so that the distance between the spring working points corresponding to the two first spring assemblies at the same end of the segment model is the target distance.

[0047] In the second aspect, an embodiment of the present invention provides a free vibration test system, comprising a segment model, four first spring assemblies arranged above the four corners of the top surface of the segment model, and four second spring assemblies arranged below the four corners of the bottom surface of the segment model; the first spring assembly and the second spring assembly both comprise a turntable and a plurality of springs with different stiffnesses installed circumferentially along the turntable; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs in the first spring assembly are vertically fixed to the bottom surface of its turntable, and the springs in the second spring assembly are vertically fixed to the top surface of its turntable; the turntable can rotate a target spring of stiffness corresponding to the first frequency to a spring working point for connection between the segment model and the target spring; the target spring can be vertically connected to the corner of the segment model when at the spring working point.

[0048] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the frequency modulation method of the free vibration test system as described in any one of the first aspects is implemented.

[0049] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the frequency modulation method of the free vibration test system as described in any one of the first aspects is implemented.

[0050] In a fifth aspect, an embodiment of the present invention provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes the frequency modulation method of the free vibration test system described in any one of the first aspects.

[0051] Compared with the related art, the embodiments of the present invention have the following beneficial effects:

[0052] The embodiment of the present invention provides a frequency modulation method for a free vibration test system, the system includes a segment model, four first spring assemblies arranged above the four corners of the top surface of the segment model, and four second spring assemblies arranged below the four corners of the bottom surface of the segment model; the first spring assembly and the second spring assembly both include a turntable and a plurality of springs with different stiffnesses installed along the circumference of the turntable; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs in the first spring assembly are vertically fixed on the bottom surface of its turntable, and the springs in the second spring assembly are vertically fixed on the top surface of its turntable; the above frequency modulation method first determines the target angle based on the received first frequency, and then controls the turntable to rotate the target spring to the spring working point according to the target angle, so that the target spring can be connected to the segment model; the target spring is a spring with a stiffness corresponding to the first frequency. That is, the present invention provides a plurality of springs with different spring stiffnesses for the free vibration test by setting a turntable-type spring assembly, and the stiffness of the spring connected to the segment model is changed by rotating the turntable, so that the vibration frequency of the segment model can be flexibly adjusted, and there is no need to frequently install and remove the spring, which can effectively improve the efficiency of the free vibration test.

[0053] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0054] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0056] Figure 1 is a structural schematic diagram of a free vibration test system provided by an embodiment of the present invention;

[0057] Figure 2 is a schematic top view of a free vibration test system provided by an embodiment of the present invention;

[0058] Figure 3 It is a flow chart of a frequency modulation method of a free vibration test system provided by an embodiment of the present invention;

[0059] Figure 4 is a schematic diagram of a connection structure between a spring and a segment model provided by an embodiment of the present invention;

[0060] Figure 5It is a structural schematic diagram of a first turntable bracket, a second turntable bracket and a clamping fixture provided by an embodiment of the present invention;

[0061] Figure 6 is a structural schematic diagram of a free vibration test system provided by another embodiment of the present invention;

[0062] Figure 7 is a flow chart of a frequency modulation method of a free vibration test system provided by another embodiment of the present invention;

[0063] Figure 8 is a schematic top view of a cross-type support arm structure provided by an embodiment of the present invention;

[0064] Fig. 9 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0066] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0067] In addition, in the description of the present specification and the appended claims, the terms "first", "second", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0068] References to "one embodiment" or "some embodiments" etc. described in the present specification mean that one or more embodiments of the present invention include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0069] In the related art, when conducting free vibration tests, elastic suspension devices are often used to provide vibration frequencies for the test models, and mainly provide vertical bending frequencies. However, the current elastic suspension devices are not flexible enough when changing the frequency, resulting in very low frequency modulation efficiency in the test. For example, some require the entire device structure to be completely dismantled first, and then reinstalled according to the required parameters; some can achieve frequency changes by adjusting certain components of the device without dismantling the device, but it can only achieve switching between two vibration frequencies, which still cannot meet the test requirements of flexible frequency modulation.

[0070] In addition, in some wind tunnel test studies, it is necessary to test the same test model at multiple frequencies, or to test different test models at different frequencies. For example, when studying the Reynolds number effect of a bridge, it may be necessary to test the vibration response of the test model at multiple continuous frequencies. However, the current free vibration test system and its frequency modulation method cannot meet the requirements of continuous frequency adjustment.

[0071] Based on the above problems, an embodiment of the present invention provides a frequency modulation method for a free vibration test system, which provides a vertical bending frequency in the vertical direction for a segment model (a test model in a free vibration test) through a first spring assembly and a second spring assembly with a turntable design. By rotating the turntable, flexible adjustment of multiple values ​​of the frequency can be achieved.

[0072] Figure 1 Schematic diagram of the structure of a free vibration test system provided by an embodiment of the present invention. Figure 1 The free vibration test system in the embodiment of the present invention includes a segment model 10, four first spring assemblies 11 arranged above the four corners of the top surface of the segment model 10, and four second spring assemblies 12 arranged below the four corners of the bottom surface of the segment model 10; the first spring assembly 11 and the second spring assembly 12 both include a turntable 13 and a plurality of springs 14 with different stiffnesses installed circumferentially along the turntable 13; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs 14 in the first spring assembly 11 are vertically fixed to the bottom surface of the turntable 13, and the springs 14 in the second spring assembly 12 are vertically fixed to the top surface of the turntable 13.

[0073] In the embodiment of the present invention, the rotating disk 13 can rotate clockwise or counterclockwise. In one possible implementation, the rotating disks 13 of the first spring assemblies 11 at different positions can rotate in different directions. In another possible implementation, the rotating disks 13 of each first spring assembly 11 can rotate in the same direction. It should be understood that the setting of the rotation direction needs to be determined by the arrangement order of the stiffness of the multiple springs 14 on each rotating disk 13.

[0074] It can be understood that the turntable 13 in the first spring assembly 11 can drive the spring 14 below it to rotate, and the turntable 13 in the second spring assembly 12 can drive the spring 14 above it to rotate. After the spring corresponding to the required test frequency (first frequency) is selected, the turntable 13 can rotate the spring to a position connected to the segment model 10, that is, the spring working point 15. The position of the spring working point 15 is as shown in FIG. Figure 1 and Figure 2 As shown. For the first spring assembly 11, the positions of the spring working points 15 of each turntable 13 on the turntable are different from each other; the same is true for the second spring assembly 12. For any of the four corners of the segment model 10, the spring working points 15 corresponding to the first spring assembly 11 above the corner and the second spring assembly 12 below the corner are collinear in the vertical direction.

[0075] When the free vibration test system in the embodiment of the present invention is working, the segment model 10 can be suspended by the springs 14 located at the spring working points 15 in the four first spring assemblies 11 above it, and supported by the springs 14 located at the spring working points in the four second spring assemblies 12 below it, and a vibration test can be performed between the four first spring assemblies 11 and the four second spring assemblies 12.

[0076] See also Figure 3 Based on the structure of the above-mentioned free vibration test system, the frequency modulation method of the free vibration test system provided by the embodiment of the present invention may include the following steps:

[0077] Step 101: Receive a first frequency.

[0078] Step 102: determine a target angle based on the first frequency.

[0079] Step 103 , controlling the turntable 13 to rotate to a target angle, so that the target spring rotates to the spring working point 15 and is connected to the segment model 10 .

[0080] The target spring refers to the spring 14 of the stiffness corresponding to the first frequency. The first frequency can be a vertical bending frequency directly set for testing, or a vertical bending frequency determined by proportionally amplifying the vertical bending frequency of the natural frequency of the real bridge corresponding to the segment model 10.

[0081] In the above embodiment, when the segment model is tested based on the free vibration test system provided by the present invention, the first frequency of the test is first obtained, and then the target angle required for the corresponding target spring to rotate to the spring working point 15 is determined according to the first frequency, and then the turntable 13 is controlled to rotate the target angle to move the target spring to the spring working point 15, so as to perform a test on the segment model at the first frequency, thereby avoiding the complicated disassembly of the working spring during the test and improving the test efficiency.

[0082] In some embodiments, the plurality of springs 14 with different stiffnesses on the rotating disk 13 are arranged at equal intervals in a clockwise or counterclockwise direction in an order of increasing stiffnesses, starting from the spring 14 with the smallest stiffness. The springs at the spring working point 15 of each rotating disk 13 are springs with the same stiffness.

[0083] Optionally, before the test begins, the spring at the spring working point 15 of each turntable 13 is a spring with minimum stiffness.

[0084] In this embodiment, the above step 102 can be implemented by steps 1021 and 1022:

[0085] Step 1021 : determining a target stiffness according to the first frequency and the mass of the segment model 10 .

[0086] For the wind tunnel test of the bridge main beam, generally speaking, the geometric scale ratio 1:n and wind speed ratio 1:s of the bridge prototype (actual bridge) can be determined according to the size of the wind tunnel and the wind speed range, and then the frequency ratio can be determined according to n and s. According to the actual size, actual mass, actual wind speed, actual frequency, geometric scale ratio, mass ratio, wind speed ratio, and frequency ratio corresponding to the bridge prototype, the geometric size, mass, wind tunnel test wind speed range, and frequency of the theoretical bridge model (or segment model) can be calculated. The frequency includes vertical bending frequency and torsional frequency.

[0087] In this embodiment, before testing the segment model, the required vertical bending frequency and torsion frequency can be obtained in advance, and the quality of the segment model can also be known. k 0 The calculation formula is:

[0088]

[0089] In the formula, m is the quality of the segment model; f v is the first frequency, namely the vertical bending frequency.

[0090] Step 1022, determining a target angle based on the target stiffness and the stiffness of the initial spring.

[0091] The initial position spring refers to the spring currently located at the spring working point 15.

[0092] Optionally, step 1022 includes: determining an angle corresponding to the arc length between the target spring and the initial spring according to the target stiffness and the stiffness of the initial spring; and determining a target angle based on the angle and the rotation direction of the turntable 13 .

[0093] The rotation direction may be a preset direction, or the rotation direction may be determined based on the angle and the spring arrangement direction. The spring arrangement direction is the direction in which the plurality of springs 14 on the rotating disk 13 are arranged from small to large in terms of stiffness.

[0094] In the above embodiment, the angle includes a first angle and a second angle, the first angle is the angle corresponding to the arc length from the initial position spring to the target spring, and the second angle is the angle corresponding to the arc length from the target spring to the initial position spring. When the rotation direction of the turntable 13 is a preset direction, the target angle referred to when rotating the target spring to the spring working point 15 may not be the minimum angle, and the minimum angle refers to the smaller angle between the first angle and the second angle. When the rotation direction is not preset, the rotation direction can be determined in real time based on the first angle, the second angle and the spring arrangement direction. For example, if the second angle is less than or equal to 180 degrees, the rotation direction is the spring arrangement direction; if the second angle is greater than 180 degrees, the rotation direction is the opposite direction of the spring arrangement direction. Such real-time determination of the rotation direction can ensure that the turntable 13 rotates as small an angle as possible, shorten the time of the frequency adjustment process, and thus improve the test efficiency.

[0095] See also Figure 4 In some embodiments, the segment model 10 may further include connectors 40 respectively disposed at the four corners of the top surface and the four corners of the bottom surface thereof; the spring working points 15 of each turntable 13 correspond to the corresponding connectors 40 in the vertical direction; and the first end 41 of each spring 14 in the turntable 13 is fixedly connected to the turntable 13. After the target spring rotates to the spring working point 15, each connector 40 of the segment model 10 is detachably connected to the second end of the corresponding target spring.

[0096] Optionally, the connecting member 40 is a magnetic connecting member. The second end 42 of each spring 14 is provided with an electromagnetic chuck 43, such as Figure 4 shown.

[0097] Optionally, the connecting member 40 is a snap ring, and the second end 42 of each spring 14 is provided with a hook; when the target spring is connected to the segment model 10, the hook at the second end 42 of the target spring hooks the corresponding snap ring.

[0098] based on Figure 4 In an embodiment, the implementation process of the above step 103 may include: controlling the electromagnetic suction cup 43 of the spring currently located at the spring working point 15 to be powered off, and then controlling the turntable 13 to rotate the target angle to drive the target spring to rotate to the spring working point 15; when the target spring rotates to the spring working point 15, controlling the electromagnetic suction cup 43 of the target spring to be powered on, and the magnetic connector of the segment model 10 is adsorbed and connected to the target spring.

[0099] See also Figure 5In some embodiments, the free vibration test system of the embodiment of the present invention may further include a first turntable bracket 51 and a second turntable bracket 52 .

[0100] The first turntable bracket 51 is used to fix the first spring assembly 11 at a preset distance above the segment model 10 ; the top of the turntable 13 of the first spring assembly 11 is fixedly connected to the first turntable bracket 51 .

[0101] The second turntable bracket 52 is used to fix the second spring assembly 12 at a preset distance below the segment model 10 ; the bottom of the turntable 13 of the second spring assembly 12 is fixedly connected to the second turntable bracket 52 .

[0102] The first turntable bracket 51 and the second turntable bracket 52 may be provided with a clamping fixture 53 .

[0103] It can be understood that the top of the turntable 13 of the first spring assembly 11 is fixedly connected to the first turntable bracket 51, and the bottom of the turntable 13 of the second spring assembly 12 is fixedly connected to the second turntable bracket 52, which means that the rotation center axis of the turntable 13 is connected to the first turntable bracket 51 or the second turntable bracket 52.

[0104] Accordingly, the frequency modulation method of the free vibration test system provided in the embodiment of the present invention may further include:

[0105] Step 104: determining a target effective number of turns of a target spring according to the first frequency.

[0106] Step 105, according to the target effective number of coils, the target number of coils in the target spring is clamped to adjust the stiffness of the target spring to the target stiffness. The target number is the difference between the original effective number of coils of the target spring and the target effective number of coils; the target stiffness is the spring stiffness calculated according to the first frequency and the mass of the segment model 10.

[0107] In this embodiment, the target spring is the spring whose stiffness is less than the target stiffness and closest to the target stiffness among all the springs 14. In this case, if the frequency condition of the test is to be met, the stiffness of the target spring can be adjusted. In this embodiment, the effective number of coils of the target spring is reduced by clamping the target number of coils in the target spring, thereby increasing the stiffness of the target spring and achieving precise adjustment of the vertical bending frequency.

[0108] In a possible implementation, the clamping fixture 53 may include a base 54, a telescopic rod 55, and a horizontal pressing plate 56. Figure 5 The base 54 is fixed on the first turntable bracket 51 and the second turntable bracket 52 ; the telescopic rod 55 is vertically fixed on the base 54 ; one end of the horizontal pressing plate 56 is fixedly connected to the telescopic end 57 of the telescopic rod 55 , and the horizontal pressing plate 56 is perpendicular to the telescopic rod 55 .

[0109] In this implementation, step 105 can be implemented through steps 1051 to 1052:

[0110] Step 1051, determining the target quantity according to the target effective number of turns and the original effective number of turns of the target spring.

[0111] Step 1052, determining the telescopic length based on the target quantity and the wire diameter of the target spring.

[0112] Step 1053, according to the telescopic length, control the telescopic rod to extend or contract to the height between the first spring coil 58 and the second spring coil 59, then control the horizontal pressure plate to be inserted between the first spring coil 58 and the second spring coil 59, and finally control the telescopic rod to contract to clamp the target number of spring coils.

[0113] The first spring coil 58 is the target number of spring coils from the first spring coil connected to the rotating disk 13; the second spring coil 59 is the spring coil adjacent to the first spring coil 58 and away from the rotating disk 13. The positions of the first spring coil 58 and the second spring coil 59 are shown in the figure below. Figure 5 shown.

[0114] In this implementation, the target number n 0 The calculation formula includes:

[0115]

[0116]

[0117]

[0118] in, k 1 is the processing spring stiffness of the target spring (N / mm), i.e., the original spring stiffness; G is the elastic shear modulus, which is a constant (MPa), generally 7.95×10 4 MPa; d is the wire diameter of the target spring (mm), n 1 is the original effective number of turns of the target spring (turns), D is the center diameter of the target spring (mm); k 2 is the target stiffness; n 2 The target effective number of laps.

[0119] In another possible implementation, the clamping fixture 53 may be a hydraulic clamp whose maximum jaw width is greater than a preset width; the preset width is determined based on the preset number of turns and the wire diameter of each spring in the first spring assembly 11. When it is necessary to reduce the effective number of turns of the target spring, the target number of spring turns are clamped by the hydraulic clamp.

[0120] In the above embodiment, on the basis of designing a turntable spring, a clamping fixture 53 is additionally provided to flexibly adjust the stiffness of the target spring, so that the first spring assembly 11 and the second spring assembly 12 can provide more frequency values ​​within a limited frequency range, thereby realizing continuous frequency adjustment to a certain extent, which provides significant convenience for in-depth research on wind tunnel tests.

[0121] See also Figure 6 In some embodiments, the free vibration test system of the present invention may further include two support rails 60 respectively disposed below the two ends of the segment model 10 ; the support rails 60 are parallel to the wide side of the segment model 10 .

[0122] like Figure 6 As shown, the free vibration test system in this embodiment includes four first turntable brackets 51 and four second turntable brackets 52, and the first turntable brackets 51 and the second turntable brackets 52 are horizontal rods. At the same time, the free vibration test system also includes four vertically arranged connecting rods 61, and the connecting rods 61 are used to fix and connect a group of first turntable brackets 51 and second turntable brackets 52 corresponding to each other up and down to form an integrated bracket 62.

[0123] The second turntable bracket 52 includes a slider 63 disposed at the bottom. The two second turntable brackets 52 disposed below the same end of the segment model 10 are both slidably connected to the bracket track 60 of the end through the slider 63; when the two integrated brackets 62 at the same end of the segment model 10 slide toward each other on the bracket track 60, the distance between the spring working points 15 corresponding to the two first spring assemblies 11 at the end of the segment model 10 decreases; when the two integrated brackets 62 at the same end of the segment model 10 slide away from each other on the bracket track 60, the distance between the spring working points 15 corresponding to the two first spring assemblies 11 at the end of the segment model 10 increases.

[0124] based on Figure 6 The structure of the free vibration test system is shown in Figure 7 FIG. 2 is a flow chart showing a frequency modulation method of a free vibration test system provided by another embodiment of the present invention. Figure 7 The frequency modulation method of the free vibration test system in the embodiment of the present invention may further include:

[0125] Step 106: Receive a second frequency.

[0126] Step 107: Determine the target distance based on the first frequency and the second frequency.

[0127] Step 108, determining the moving distance of the integrated bracket according to the target distance and the initial distance.

[0128] The initial distance is the distance between the spring working points 15 corresponding to the two first spring components 11 at the same end of the current segment model 10 .

[0129] Step 109 , based on the moving distance, control the two integrated brackets at the same end of the segment model 10 to move toward or away from each other along the bracket track, so that the distance between the spring working points 15 corresponding to the two first spring assemblies 11 at the same end of the segment model 10 is the target distance.

[0130] The second frequency in this embodiment refers to the torsional frequency of the segment model 10. In the free vibration test research, whenever the model is replaced or the vertical bending frequency of the model is changed, the system device needs to be adjusted accordingly to provide a suitable torsional frequency for the model. The traditional elastic suspension device also cannot adjust the torsional frequency, and the device needs to be reassembled every time the torsional frequency is changed.

[0131] In the embodiment of the present invention, the torsion frequency is given by setting the distance between the two spring working points 15 above / below the same end of the segment model 10. Since the distance and the vertical bending frequency and the torsion frequency conform to the relationship , L is the distance between the two spring working points 15, I m is the moment of inertia of segment model 10, f t is the second frequency, i.e. the torsion frequency. Therefore, when the required frequency changes, the distance can be adjusted L To provide the corresponding torsional frequency for the model. Among them, the moment of inertia I m and quality m is a known quantity.

[0132] Combination Figure 6 It can be understood that after the target distance is calculated based on the first frequency and the second frequency, combined with the distance between the two spring working points 15 above / below the same end of the segment model 10 in the system, the moving distance and moving direction of each integrated bracket 62 can be determined, and then each integrated bracket 62 is controlled to move the moving distance in its moving direction, thereby realizing the adjustment of the torsional frequency.

[0133] In other embodiments, different from Figure 6In the embodiment shown, the first turntable bracket 51 and the second turntable bracket 52 are not horizontal rods. The first turntable bracket 51 and the second turntable bracket 52 can also be various support arms. For example, they can be arc-shaped support arms, cross-shaped support arms, L-shaped support arms, etc.

[0134] When the first turntable bracket 51 and the second turntable bracket 52 are cross-type support arms, as shown in FIG. Figure 8 As shown, the cross-type support arm may include a first support arm 81 and a second support arm 82, the first support arm 81 intersects with the vertical line where the spring working point 15 is located, the second support arm 82 is parallel to the wide side of the segment model 10, and the two second support arms 82 corresponding to each other are fixedly connected. In this way, it can be ensured that the clamping fixture 53 can work near the spring working point 15 to achieve the vertical bending frequency adjustment function, and at the same time, it can also be ensured that the first spring assembly 11 and the second spring assembly can move smoothly along the direction of the bracket track 60, thereby achieving continuous adjustment of the vertical bending frequency and convenient adjustment of the torsion frequency.

[0135] In some embodiments, based on Figure 6 In the embodiment shown, the connecting rod 61 can also be extended and retracted in the vertical direction, thereby changing the distance between the first spring assembly 11 and the second spring assembly 12. The frequency modulation method in the embodiment of the present invention can also include: before the target spring rotates to the spring working point 15, controlling the connecting rod 61 to extend to a first preset height; thereafter, controlling the rotating disk 13 to rotate to a target angle; after the target spring rotates to the spring working point 15, controlling the connecting rod 61 to descend to a second preset height.

[0136] In the above embodiment, the distance between the upper and lower springs is adjusted through the telescopic function of the connecting rod 61, which can ensure that the error rate of the system is reduced.

[0137] In some embodiments, the free vibration test system in the embodiment of the present invention may further include a mobile support and a model track, and the mobile support may be used to move the segment model 10 along the model track to between the first spring assembly 11 and the second spring assembly 12. Accordingly, the frequency modulation method of the free vibration test system in the embodiment of the present invention may further include: before receiving the first frequency, controlling the mobile support to move the segment model 10 to between the first spring assembly 11 and the second spring assembly 12.

[0138] The frequency modulation method of the free vibration test system is based on the design of the turntable spring and the clamping fixture. The springs with different stiffness are replaced by rotating the turntable 13, and the stiffness of a single spring is adjusted by clamping the target number of spring coils, thereby realizing multi-value continuous adjustment of the vertical bending frequency. At the same time, the torsional frequency is adjusted by the bracket track 60 and the integrated bracket 62 that can move on the bracket track 60. The frequency modulation method has multiple adjustable frequencies and a high degree of automation, which can effectively improve the test efficiency.

[0139] It should be understood that the serial numbers of the above steps do not represent the execution order of the steps.

[0140] Fig. 9 Schematic diagram of an electronic device provided by an embodiment of the present invention. Fig. 9 As shown, the electronic device 90 of this embodiment includes: a processor 91 and a memory 92. The memory 92 stores a computer program. When the processor 91 executes the computer program, the steps in the above-mentioned various method embodiments are implemented.

[0141] Exemplarily, the computer program may be divided into one or more modules / units, which are stored in the memory 92 and executed by the processor 91 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program in the electronic device 90.

[0142] The electronic device 90 may include, but is not limited to, a processor 91 and a memory 92. Those skilled in the art will appreciate that Fig. 9 It is only an example of the electronic device 90 and does not constitute a limitation of the electronic device 90. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 90 may also include input and output devices, network access devices, buses, etc.

[0143] The processor 91 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0144] The memory 92 may be an internal storage unit of the electronic device 90, such as a hard disk or memory of the electronic device 90. The memory 92 may also be an external storage device of the electronic device 90, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 90. Further, the memory 92 may also include both an internal storage unit of the electronic device 90 and an external storage device. The memory 92 is used to store computer programs and other programs and data required by the electronic device 90. The memory 92 may also be used to temporarily store data that has been output or is to be output.

[0145] For the convenience and simplicity of description, only the division of the above functional modules / units is used as an example for illustration. In actual applications, the above functions can be assigned to different functional modules / units as needed. The above modules / units can be implemented in the form of hardware, software, or a combination of hardware and software.

[0146] The embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the methods in the above method embodiments are implemented.

[0147] The embodiment of the present invention further provides a computer program product, including a computer program. When the computer program is executed by a processor, the methods in the above method embodiments are implemented.

[0148] The computer program includes computer program code, which may be in source code form, object code form, executable file or some intermediate form, etc. Computer readable media may include: any entity or device capable of carrying computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0149] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. If there is no special explanation and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features in different embodiments can be combined to form a new embodiment according to their internal logical relationship.

[0150] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A frequency modulation method for a free vibration test system, characterized in that: The free vibration test system comprises a segment model, four first spring assemblies arranged above the four corners of the top surface of the segment model, and four second spring assemblies arranged below the four corners of the bottom surface of the segment model; the first spring assembly and the second spring assembly both comprise a turntable and a plurality of springs with different stiffnesses installed circumferentially along the turntable; the plurality of different stiffnesses correspond to a plurality of different frequencies respectively; the springs in the first spring assembly are vertically fixed on the bottom surface of the turntable, and the springs in the second spring assembly are vertically fixed on the top surface of the turntable; the method comprises: receiving a first frequency; determining a target angle based on the first frequency; The turntable is controlled to rotate to the target angle so that the target spring rotates to the spring working point and is connected to the segment model; the target spring is a spring with a stiffness corresponding to the first frequency.

2. The frequency modulation method of the free vibration test system according to claim 1, characterized in that: The plurality of springs of different stiffness on the rotating disk are arranged at equal intervals in a clockwise or counterclockwise direction in the order of increasing stiffness, starting from the spring with the smallest stiffness; The determining of the target angle based on the first frequency includes: determining a target stiffness according to the first frequency and the mass of the segment model; The target angle is determined based on the target stiffness and the stiffness of the initial position spring; wherein the initial position spring is a spring currently located at the spring working point.

3. The frequency modulation method of the free vibration test system according to claim 2, characterized in that: The step of determining the target angle based on the target stiffness and the stiffness of the initial spring comprises: Determine the angle corresponding to the arc length between the target spring and the initial spring according to the target stiffness and the stiffness of the initial spring; Determining the target angle based on the included angle and the rotation direction of the turntable; Wherein, the rotation direction is a preset direction, or the rotation direction is determined based on the angle and the spring arrangement direction; the spring arrangement direction is the direction in which multiple springs on the turntable are arranged from small to large in terms of stiffness.

4. The frequency modulation method of the free vibration test system according to claim 1, characterized in that: The segment model includes connecting pieces respectively arranged at the four corners of the top surface and the four corners of the bottom surface; the spring working points of each turntable correspond to the corresponding connecting pieces in the vertical direction; the first end of each spring in the turntable is fixedly connected to the turntable; After the target spring rotates to the spring working point, each connecting piece of the segment model is detachably connected to the second end of its corresponding target spring.

5. The frequency modulation method of the free vibration test system according to claim 4, characterized in that: The connecting member is a magnetic connecting member; the second end of each spring is provided with an electromagnetic chuck; The step of controlling the turntable to rotate the target angle so that the target spring rotates to the spring working point and is connected to the segment model includes: Control the electromagnetic chuck of the spring currently located at the spring working point to cut off the power, and then control the turntable to rotate to a target angle, so as to drive the target spring to rotate to the spring working point; When the target spring rotates to the spring working point, the electromagnetic suction cup of the target spring is controlled to be energized, and the magnetic connector of the segment model is adsorbed and connected with the target spring.

6. The frequency modulation method of the free vibration test system according to claim 1, characterized in that: The free vibration test system also includes a first turntable bracket and a second turntable bracket; The first turntable bracket is used to fix the first spring assembly at a preset distance above the segment model; the top of the turntable of the first spring assembly is fixedly connected to the first turntable bracket; The second turntable bracket is used to fix the second spring assembly at the preset distance below the segment model; the bottom of the turntable of the second spring assembly is fixedly connected to the second turntable bracket; The first turntable bracket and the second turntable bracket are both provided with a clamping fixture; The method further comprises: Determining a target effective number of turns of the target spring according to the first frequency; According to the target effective number of turns, a continuous target number of spring turns in the target spring are clamped to adjust the stiffness of the target spring to the target stiffness; wherein the target number is the difference between the original effective number of turns of the target spring and the target effective number of turns; and the target stiffness is the spring stiffness calculated based on the first frequency and the mass of the segment model.

7. The frequency modulation method of the free vibration test system according to claim 6, characterized in that: The clamping fixture comprises a base, a telescopic rod and a horizontal pressing plate; the base is fixed on the first turntable bracket and the second turntable bracket; the telescopic rod is vertically fixed on the base; one end of the horizontal pressing plate is fixedly connected to the telescopic end of the telescopic rod, and the horizontal pressing plate is perpendicular to the telescopic rod; The step of clamping a target number of continuous spring coils in the target spring according to the target effective number of coils comprises: Determining the target quantity according to the target effective number of turns and the original effective number of turns of the target spring; Determining a telescopic length based on the target quantity and the target spring wire diameter; According to the telescopic length, the telescopic rod is controlled to extend or contract to a height between the first spring coil and the second spring coil, then the horizontal pressing plate is controlled to be inserted between the first spring coil and the second spring coil, and finally the telescopic rod is controlled to contract to clamp the target number of spring coils; Among them, the first spring coil is the target number of spring coils starting from the first spring coil connecting the target spring and the rotating disk; the second spring coil is the spring coil adjacent to the first spring coil and away from the rotating disk.

8. The frequency modulation method of the free vibration test system according to claim 6, characterized in that: The clamping fixture is a hydraulic pliers, and the maximum jaw width of the hydraulic pliers is greater than a preset width; the preset width is determined based on a preset number of turns and a wire diameter of each spring in the first spring assembly.

9. The frequency modulation method of the free vibration test system according to claim 6, characterized in that: The free vibration test system further comprises two support rails respectively arranged below the two ends of the segment model; the support rails are parallel to the wide side of the segment model; The free vibration test system comprises four first turntable brackets and four second turntable brackets, wherein the first turntable bracket and the second turntable bracket are horizontal rods; The free vibration test system further comprises four vertically arranged connecting rods, wherein the connecting rods are used to fix and connect a group of first turntable brackets and second turntable brackets corresponding to each other up and down to form an integrated bracket; The second turntable bracket includes a slider disposed at the bottom; the two second turntable brackets disposed below the same end of the segment model are both slidably connected to the bracket track of the end through the slider; when the two integrated brackets at the same end of the segment model slide toward each other on the bracket track, the distance between the spring working points corresponding to the two first spring assemblies at the end of the segment model is reduced; When the two integrated brackets at the same end of the segment model slide back to back on the bracket track, the distance between the spring working points corresponding to the two first spring assemblies at the end of the segment model increases.

10. The frequency modulation method of the free vibration test system according to claim 9, characterized in that: The method further comprises: receiving a second frequency; determining a target distance based on the first frequency and the second frequency; Determine the moving distance of the integrated support according to the target distance and the initial distance; wherein the initial distance is the distance between the spring working points corresponding to the two first spring assemblies at the same end of the current segment model; Based on the moving distance, the two integrated brackets at the same end of the segment model are controlled to move toward or away from each other along the bracket track so that the distance between the spring working points corresponding to the two first spring assemblies at the same end of the segment model is the target distance.

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