Device and method for testing dynamic stiffness and structural loss factor of axisymmetric vibration absorber

Abstract

The present invention provides a dynamic stiffness and structural loss factor testing device and method for an axisymmetric vibration damper, wherein the testing method comprises the following steps: first, a mass block assembly is supported by a plurality of vibration dampers, and a plurality of acceleration sensors are installed on the mass block assembly; second, the mass block assembly is excited by a hammer method or an exciter method, and a frequency response function is obtained by testing; then, the frequency response function obtained by the excitation is converted to the mass center of mass assembly, and the frequency response function of the origin of the mass Z degree of freedom and the frequency response function of the origin of the mass RZ degree of freedom are obtained; finally, the dynamic stiffness and structural loss factor of the vibration damper in the vertical and horizontal directions are calculated by the frequency response function of the origin of the mass Z degree of freedom and the frequency response function of the origin of the mass RZ degree of freedom. The testing device and method of the present invention are simple to operate, and the dynamic stiffness and structural loss factor of the vibration damper in the vertical and horizontal directions can be accurately and quickly obtained in one complete test.

Description

Technical Field

[0001] The invention belongs to the technical field of vibration damper testing, and in particular relates to a device and method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper. Background Art

[0002] Shock absorbers are widely used in electromechanical products with vibration source components such as compressors, motors, and engines. They mainly support the vibration source components and reduce vibration. For example, the foot pad of the air-conditioning compressor is a typical shock absorber. The vibration reduction principle of the shock absorber is: the shock absorber usually has a relatively small dynamic stiffness and can play a vibration isolation role; the shock absorber usually has a high structural loss factor, and its dynamic deformation can dissipate vibration energy and play a vibration damping role. Corresponding to the two effects of vibration isolation and vibration damping, the most important parameters of the shock absorber are dynamic stiffness and structural loss factor. Among them, dynamic stiffness reflects the elasticity of the shock absorber during dynamic deformation, and structural loss factor reflects the damping during dynamic deformation. Accurately obtaining the dynamic stiffness and structural loss factor of the shock absorber can be used to quantitatively evaluate the dynamic performance of the shock absorber, and can also be used for dynamic simulation analysis of electromechanical products. Many shock absorbers contain rubber or other nonlinear materials, which produce a large pre-deformation under the gravity of the vibration source component, and the dynamic stiffness of the shock absorber after deformation will also change greatly. In other words, the preload of the shock absorber has a great influence on its dynamic stiffness, so the dynamic stiffness test must be carried out under the preload state.

[0003] At present, the methods for testing dynamic stiffness can be roughly divided into two categories. One is the forced vibration method, which is often tested using a dynamic mechanical analyzer (DMA) or similar testing equipment. One end of the specimen is fixed, and the other end is forced to reciprocate. The dynamic stiffness and structural loss factor are calculated based on the dynamic displacement and reaction force. This method is mainly used for material specimens with simple structures. When it comes to a certain type of shock absorber, due to its relatively complex shape, it is difficult to clamp and test it on the DMA, so another type of testing method, the free vibration method, is usually given priority.

[0004] The free vibration method can be understood as a spring-mass assembly vibration system, which applies vibration excitation to the system and identifies dynamic parameters based on its free vibration, except that the "spring" here refers to the shock absorber to be tested. Since the mass assembly itself has gravity, it can simulate the preload condition, so the free vibration method is particularly suitable for shock absorber testing. In the existing free vibration methods: for example, the solutions disclosed in document 1 [Lin TR, Farag NH and Pan J. Evaluation of frequency dependent rubber mount siffness and damping by impact test. Applied Acoustics, 2005, 66 (7): 829-844] and Chinese invention patent CN201510350505.5 can only test the dynamic stiffness and structural loss factor in one direction. In fact, after the shock absorber is preloaded, its dynamic stiffness in the vertical direction and the horizontal direction is very different. The dynamic stiffness and structural loss factor in one direction cannot fully represent its dynamic behavior. In addition, for example, in document 2 [Tomatsu T, Okada T, Ikeno T, et al. A method to identify the stiffness of engine mounts using experimental modal analysis. Proceedings of the ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, 2005, 1: 265-272], although the scheme disclosed therein can test both the vertical and horizontal directions simultaneously, it can only obtain the dynamic stiffness, but cannot obtain the structural loss factor. Summary of the invention

[0005] The object of the present invention is to provide a testing device and method for simultaneously obtaining the dynamic stiffness and structural loss factor of an axisymmetric vibration absorber in both vertical and horizontal directions.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solution: a method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper, characterized in that it includes the following steps.

[0007] S1: Use n identical shock absorbers to support a mass assembly, where n ≥ 3, and the positions of the n shock absorbers should satisfy: the gravity of the mass assembly is evenly distributed to the n shock absorbers.

[0008] S2: Install multiple acceleration sensors on the mass assembly.

[0009] S3: The mass block assembly is excited by a hammer method or a shaker method. During the test, multiple excitation points are excited in sequence to obtain a frequency response function.

[0010] S4: The frequency response function obtained in step S3 is converted to the center of mass of the mass block assembly to obtain the center of mass Z degree of freedom origin frequency response function and the center of mass RZ degree of freedom origin frequency response function.

[0011] S5: The dynamic stiffness and structural loss factor of the shock absorber in the vertical direction are calculated by the frequency response function of the center of mass Z degree of freedom origin; the dynamic stiffness and structural loss factor of the shock absorber in the horizontal direction are calculated by the frequency response function of the center of mass RZ degree of freedom origin.

[0012] In the specification of the present invention, the coordinate system adopts the Cartesian coordinate system, and the Z axis is vertically upward.

[0013] Furthermore, in step S2, the number of acceleration test channels N on the mass block assembly is ≥6, and in the frequency response function test of S3, these N acceleration test channels are recorded simultaneously; in step S3, the number of excitation points M on the mass block assembly is ≥6.

[0014] Furthermore, in step S4, the formula used to convert the frequency response function obtained by the test to the centroid is:

[0015]

[0016] In formula (1), H is an N×M matrix composed of the frequency response functions obtained by the test, each column corresponds to an excitation point, and each row corresponds to an acceleration test channel; The 6×6 matrix is ​​composed of the frequency response function of the center of mass. The third diagonal element is the frequency response function of the center of mass Z degree of freedom origin, and the sixth diagonal element is the frequency response function of the center of mass RZ degree of freedom origin; the superscript T represents the transpose operation of the matrix, and the superscript -1 represents the inverse operation of the matrix; T a is the acceleration transformation matrix, T f is the excitation transformation matrix, and their specific expressions are as follows:

[0017]

[0018]

[0019]

[0020] In T a , T f In the expressions of these two matrices: is the coordinate of the center of mass of the mass block assembly; (x i ,y i ,z i ) is the coordinate of the ith channel acceleration sensor, {d xi ,d yi ,d zi} T is the unit vector along the acceleration test direction of the i-th channel; (x' k ,y' k ,z' k ) is the coordinate of the kth excitation point, {d' xk ,d' yk ,d' zk} T is the unit vector along the excitation direction of the kth excitation point.

[0021] Furthermore, in step S5, the center of mass Z degree of freedom origin frequency response function The maximum amplitude and its corresponding angular frequency ω 33,p Calculate the dynamic stiffness k of the shock absorber in the vertical direction z and structural loss factor g z , the formula used is:

[0022]

[0023]

[0024] Frequency response function of the origin of the center of mass RZ degree of freedom The maximum amplitude and its corresponding angular frequency ω 66,p Calculate the dynamic stiffness k of the shock absorber in the horizontal direction x and structural loss factor g x , the formula used is:

[0025]

[0026]

[0027] In formula (2) to formula (5), n is the number of shock absorbers used in the test device; M is the total mass supported by n shock absorbers; I z is the moment of inertia of the mass block assembly about the vertical center line passing through its center of mass; the center of mass of each of the n shock absorbers has a distance value from the vertical line passing through the center of mass of the mass block assembly, and r is the average of these n distance values.

[0028] Furthermore, before calculating the dynamic stiffness and structural loss factor in the vertical and horizontal directions, the peak of the amplitude-frequency curve of the frequency response function of the origin of the center of mass Z degree of freedom is calculated. The peak of the amplitude-frequency curve of the frequency response function of the origin of the mass center RZ degree of freedom The corrected vertex is the intersection of the extension line of the line connecting the two points on its left side and the extension line of the line connecting the two points on its right side, and the height of the corrected vertex is greater than all the original data points.

[0029] The invention discloses a dynamic stiffness and structural loss factor testing device for an axisymmetric vibration absorber, which is characterized by comprising a vibration absorber testing installation component, an acceleration sensor, an exciter, and a data acquisition system; the acceleration sensor and the exciter are respectively connected to the data acquisition system.

[0030] The shock absorber test installation assembly includes a base and a mass block assembly, and the shock absorber is installed between the mass block assembly and the base; a plurality of acceleration sensors are installed on the mass block assembly to monitor the six degrees of freedom of movement of the mass block assembly;

[0031] Furthermore, the exciter is a hammer or a vibration exciter.

[0032] Furthermore, the mass block assembly comprises a polygonal bottom plate and a mass block fixedly connected to the polygonal bottom plate. Preferably, the mass block comprises one or more mass stacking blocks, and the mass stacking blocks are detachably fixedly connected to the polygonal bottom plate.

[0033] Furthermore, the shock absorber test installation assembly also includes a connecting structure, which includes an upper connecting member and a lower connecting member, the upper connecting member is fixedly connected to the mass assembly, the lower connecting member is fixedly connected to the base, and the shock absorber is installed between the upper connecting member and the lower connecting member.

[0034] The beneficial effect of the present invention is that the test device and method of the present invention are simple to operate, and the dynamic stiffness and structural loss factor of the shock absorber in the vertical and horizontal directions can be accurately and quickly obtained in one test. Specifically, after the frequency response function of the mass block assembly obtained by the test is converted to the center of mass, the decoupled center of mass Z degree of freedom origin frequency response function and center of mass RZ degree of freedom origin frequency response function are used to calculate the stiffness and structural loss factor in the vertical and horizontal directions respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of the testing device of the present invention.

[0036] Figure 2 It is a structural schematic diagram of the shock absorber test installation assembly in the test device of the present invention.

[0037] Figure 3It is a structural schematic diagram of the connection structure in the testing device of the present invention.

[0038] Figure 4 Another structural schematic diagram of the testing device of the present invention.

[0039] Figure 5 It is a schematic diagram of the process of the present invention.

[0040] Figure 6 It is a schematic diagram of the correction of the peak of the amplitude-frequency curve of the origin frequency response function in the present invention.

[0041] Figure 7 A schematic diagram of the structure of a shock absorber.

[0042] Figure 8 It is a schematic diagram of the state after the air-conditioning compressor and the shock absorber are connected in the test case of the present invention.

[0043] Fig. 9 It is a schematic diagram of the structure of the shock absorber test installation assembly in the test case of the present invention.

[0044] Fig.10 It is the amplitude-frequency curve of the frequency response function of the origin of the center of mass Z degree of freedom in the test case of the present invention.

[0045] Fig.11 It is the amplitude-frequency curve of the frequency response function of the origin of the mass center RZ degree of freedom in the test case of the present invention.

[0046] In the figure: 1- shock absorber test installation component; 11- base; 12- mass block assembly; 121- polygonal bottom plate; 122- mass stacking block; 13- connection structure; 131- upper connecting piece; 132- lower connecting piece; 2- acceleration sensor; 3- hammer; 4- data acquisition device; 5- computer; 6- exciter; 7- power amplifier; 10- shock absorber; 20- air conditioning compressor; 30- chassis. DETAILED DESCRIPTION

[0047] like Figure 1 , 2 As shown, a dynamic stiffness and structural loss factor testing device of an axisymmetric vibration absorber of the present invention comprises a vibration absorber testing installation component 1, an acceleration sensor 2, an exciter and a data acquisition system.

[0048] Specifically, the shock absorber test installation assembly 1 comprises a base 11 and a mass assembly 12, and the shock absorber 10 is installed between the base 11 and the mass assembly 12. A plurality of acceleration sensors 2 are installed on the mass assembly 12 to monitor the vibration of the six degrees of freedom of the mass assembly. Figure 1In the test device shown, the data acquisition system includes a data acquisition device 4 and a computer 5, the data acquisition device 4 and the computer 5 are connected, and the computer 5 is installed with matching test software. The exciter is a force hammer 3, and the acceleration sensor 2 and the force hammer 3 are respectively connected to the data acquisition device 4.

[0049] The six degrees of freedom of the mass assembly are: translational freedom along the +X or -X direction (X degree of freedom for short), translational freedom along the +Y or -Y direction (Y degree of freedom for short), translational freedom along the +Z or -Z direction (Z degree of freedom for short), rotational freedom with the rotation axis passing through the center of mass and parallel to the X coordinate axis (RX degree of freedom for short), rotational freedom with the rotation axis passing through the center of mass and parallel to the Y coordinate axis (RY degree of freedom for short), and rotational freedom with the rotation axis passing through the center of mass and parallel to the Z coordinate axis (RZ degree of freedom for short). The center of mass motion of the mass assembly can always be decomposed into these six degrees of freedom.

[0050] Specifically, the mass block assembly 12 includes a polygonal bottom plate 121 and a mass block fixedly connected to the polygonal bottom plate. Preferably, the mass block can be assembled, which includes one or more mass stacking blocks, and the mass stacking block 122 is detachably fixedly connected to the polygonal bottom plate 121. Specifically, when there are two or more mass stacking blocks 122, the connection between the mass stacking blocks can be in the following two ways: 1. Adjacent mass stacking blocks 122 are fixedly connected by screws, and the bottom mass stacking block 122 is connected to the polygonal bottom plate 121. Since the mass block is composed of one or more mass stacking blocks 122, during testing, according to the actual load-bearing capacity of the shock absorber, suitable mass stacking blocks 122 can be flexibly selected for combination, so that the load-bearing capacity of each shock absorber is close to its actual load-bearing capacity during operation, so as to meet the test of shock absorbers with different load-bearing capacities, and has a wide range of applications. Specifically, the polygonal bottom plate is an equilateral polygonal bottom plate with a thickness of ≥10 mm.

[0051] like Figure 2 , 3As shown, the shock absorber test installation assembly 1 also includes a connection structure 13, which includes an upper connection member 131 and a lower connection member 132. The upper connection member 131 is fixedly connected to the polygonal bottom plate 121 of the mass assembly 12, and the lower connection member 132 is fixedly connected to the base 11. The shock absorber 10 is installed between the upper connection member 131 and the lower connection member 132. The connection structure 13 is mainly used to install the shock absorber. Specifically, the structural shape and size of the part of the connection structure 13 that contacts and cooperates with the shock absorber are the same as the installation connection structure of the shock absorber 10 under actual working conditions. In this way, during the test, it can be ensured that the constraint conditions and stress distribution of the shock absorber are the same as the actual situation, so that the dynamic stiffness and structural loss factor obtained by the test are closer to the real value; the installation structure can be easily disassembled and replaced, so that it can adapt to shock absorbers of different shapes and sizes within a certain range.

[0052] In addition, in actual testing, in addition to the hammer, other exciters can also be used, such as the vibration exciter 6. Figure 4 As shown, the vibration exciter 6 is first connected to the power amplifier 7, and then the power amplifier 7 is connected to the data collector 4. In this way, the vibration exciter 6 can replace the hammer 3 to achieve the same effect.

[0053] like Figure 5 As shown, a method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper of the present invention is performed using the above-mentioned testing device and specifically includes the following steps.

[0054] S1: Use n identical shock absorbers to support a mass assembly, where n ≥ 3, and the positions of the n shock absorbers should satisfy: the gravity of the mass assembly is evenly distributed to the n shock absorbers.

[0055] S2: Multiple acceleration sensors are mounted on the surface of the mass block assembly by pasting or other fixing methods. The total number of acceleration test channels of these acceleration sensors is N ≥ 6. In the frequency response function test, these N acceleration test channels are recorded simultaneously.

[0056] S3: Excite the mass block assembly by hammering or vibrator method. In the frequency response function test, the number of excitation points on the mass block assembly is M≥6, and each excitation point is excited in turn to obtain the frequency response function.

[0057] S4: Convert the frequency response function obtained in step S3 to the center of mass of the mass block assembly to obtain the center of mass Z freedom origin frequency response function and the center of mass RZ freedom origin frequency response function. Specifically, the formula used to convert the frequency response function obtained by the test to the center of mass is:

[0058]

[0059] In formula (1), H is an N×M matrix composed of the frequency response functions obtained by the test, each column corresponds to an excitation point, and each row corresponds to an acceleration test channel; The 6×6 matrix is ​​composed of the frequency response function of the center of mass. The third diagonal element is the frequency response function of the center of mass Z degree of freedom origin, and the sixth diagonal element is the frequency response function of the center of mass RZ degree of freedom origin; the superscript T represents the transpose operation of the matrix, and the superscript -1 represents the inverse operation of the matrix; T a is the acceleration transformation matrix, T f is the excitation transformation matrix, and their specific expressions are as follows:

[0060]

[0061]

[0062]

[0063] In T a , T f In the expressions of these two matrices: is the coordinate of the center of mass of the mass block assembly; (x i ,y i ,z i ) is the coordinate of the ith channel acceleration sensor, {d xi ,d yi ,d zi} T is the unit vector along the acceleration test direction of the i-th channel; (x' k ,y' k ,z' k ) is the coordinate of the kth excitation point, {d' xk ,d' yk ,d' zk} T is the unit vector along the excitation direction of the kth excitation point.

[0064] S5: The dynamic stiffness and structural loss factor of the shock absorber in the vertical direction are calculated by the frequency response function of the center of mass Z degree of freedom origin; the dynamic stiffness and structural loss factor of the shock absorber in the horizontal direction are calculated by the frequency response function of the center of mass RZ degree of freedom origin.

[0065] Specifically, in step S5, the center of mass Z degree of freedom origin frequency response function The maximum amplitude and its corresponding angular frequency ω 33,p Calculate the dynamic stiffness k of the shock absorber in the vertical direction z and structural loss factor g z , the formula used is:

[0066]

[0067]

[0068] Frequency response function of the origin of the center of mass RZ degree of freedom The maximum amplitude and its corresponding angular frequency ω 66,p Calculate the dynamic stiffness k of the shock absorber in the horizontal direction x and structural loss factor g x , the formula used is

[0069]

[0070]

[0071] In formula (2) to formula (5), n is the number of shock absorbers used in the test device; m is the total mass supported by n shock absorbers; I z is the moment of inertia of the mass block assembly about the vertical center line passing through its center of mass; the center of mass of each of the n shock absorbers has a distance value from the vertical line passing through the center of mass of the mass block assembly, and r is the average of these n distance values.

[0072] Preferably, before calculating the dynamic stiffness and structural loss factor in the vertical and horizontal directions, the peak of the amplitude-frequency curve of the frequency response function of the origin of the center of mass Z degree of freedom is calculated. The peak of the amplitude-frequency curve of the frequency response function of the origin of the mass center RZ degree of freedom The corrected vertex is the intersection of the extension line of the line connecting the two points on its left side and the extension line of the line connecting the two points on its right side, and the height of the corrected vertex is greater than all the original data points; Figure 6 shown.

[0073] The principle of the method of the present invention is: after converting the frequency response function of the mass block assembly obtained by the test to the center of mass, the decoupled center of mass Z degree of freedom origin frequency response function and center of mass RZ degree of freedom origin frequency response function can be obtained, and their vibration law is the same as that of the single degree of freedom vibration system, and then they can be easily used to identify and calculate the stiffness and damping of the vibration system. Since the natural frequency corresponding to the deformation formation of the mass block assembly is very high, it can be considered as a rigid body in the lower frequency range, so the stiffness and damping of the vibration system mainly depend on the shock absorber. Therefore, the dynamic stiffness and structural loss factor of the shock absorber in the preload state can be calculated using the peak points of the center of mass Z degree of freedom origin frequency response function and the center of mass RZ degree of freedom origin frequency response function of the mass block assembly.

[0074] The following is an example of a specific test case: Figure 7As shown in the figure, this is a shock absorber (also commonly called a vibration isolator, foot pad, suspension, or vibration damping pad) made of rubber material. Figure 8 As shown, this vibration absorber 10 is used for a certain type of air conditioner outdoor unit. This vibration absorber 10 is placed between the air conditioner compressor 20 and the chassis 30, which can reduce the transmission of compressor vibration to the chassis. At the same time, its material damping can reduce the vibration of the compressor. A through hole is provided in the middle of the vibration absorber 10 for the bolt to pass through. There is a clearance fit between the through hole and the bolt. The bolt is fixed to the chassis to prevent the vibration absorber 10 from moving out of position.

[0075] Now the stiffness and structural loss factor of the shock absorber are tested and calculated according to the method of the present invention:

[0076] The first step is to select a mass block assembly that is close to the total mass of the compressor, and install multiple vibration dampers and the mass block assembly. Fig. 9 As shown, three vibration damping blocks are used as support. The total mass of the compressor, 7.90kg, is divided by the number of vibration dampers used in the compressor, and the load-bearing capacity of each vibration damper in the working state is approximately equal to 2.63kg. Therefore, what needs to be tested is the dynamic stiffness and structural loss factor of this vibration damper when it bears the weight corresponding to the mass of 2.63kg. By combining the mass superposition blocks, the mass of the mass block assembly is equal to 7.45kg, so each vibration damper bears 2.48kg in the test state. Because the mass of the mass block assembly is not continuously adjustable, there is inevitably a deviation between the vibration damper load-bearing capacity in the test state and the working state. In this embodiment, the deviation is 5.69%, which is usually negligible.

[0077] In the second step, three acceleration sensors are installed on the mass block assembly, namely acceleration sensor JS1, acceleration sensor JS2 and acceleration sensor JS3. The installation positions are as follows: Fig. 9 As shown. In this embodiment, the Z axis of the Cartesian coordinate system is vertically upward, the origin of the coordinate system is defined on the axis of the mass block assembly, and the height of the origin is flush with the support surface of the shock absorber, where the support surface refers to the plane where the shock absorber contacts the upper connector 131. The three acceleration sensors are respectively connected to the data collector, and the data collector is connected to a computer installed with corresponding test software. The specific acceleration test channels are shown in Table 1. The X degree of freedom movement can be detected by channel 1 or channel 5, the Y degree of freedom movement can be detected by channel 2 or channel 6, the Z degree of freedom movement can be detected by channel 3, channel 4, channel 5 or channel 7, the RX degree of freedom movement can be calculated by channels 3, 4, and 7, the RY degree of freedom movement can be calculated by channels 2 and 6, and the RZ degree of freedom movement can be calculated by channels 2 and 6. It can be seen that each degree of freedom can be tested by one or more acceleration sensors.

[0078]

[0079] The third step is to use the hammer method to hammer the mass block assembly to test and obtain the frequency response function of the mass block assembly. There are 8 excitation points, and the specific positions of the excitation points are as follows: Fig. 9 The eight points JLD 1 to JLD8 are marked in the figure. Each excitation point is stimulated in turn, and two or more excitation points are not stimulated at the same time. The details are as follows in Table 2:

[0080]

[0081] In the fourth step, the frequency response function obtained in the third step is converted to the center of mass of the mass block assembly through the above formula (1), and the center of mass Z degree of freedom origin frequency response function and the center of mass RZ degree of freedom origin frequency response function are obtained. The specific amplitude-frequency curves (abbreviated as amplitude-frequency curves) are as follows: Fig.10 , Fig.11 The horizontal axis of the amplitude-frequency curve can be frequency or angular frequency. Fig.10 and Fig.11 The frequency is used as the horizontal axis in Hz. The angular frequency is 2π times the frequency, and the unit of angular frequency is rad / s.

[0082] The fifth step is to correct the peaks of the amplitude-frequency curve of the frequency response function of the origin of the center of mass Z degree of freedom and the peaks of the amplitude-frequency curve of the frequency response function of the origin of the center of mass RZ degree of freedom. Then, the dynamic stiffness and structural loss factor of the shock absorber in the vertical direction are calculated from the corrected peaks of the frequency response function of the origin of the center of mass Z degree of freedom; the calculation is performed using the above formulas (2)-(3), and the results are as follows: The dynamic stiffness k of the shock absorber in the vertical direction is z =53756.3 (N·m); Structural loss factor of the shock absorber in the vertical direction g z =0.1154. The dynamic stiffness and structural loss factor of the shock absorber in the horizontal direction are calculated from the modified center of mass RZ freedom origin frequency response function vertex; the calculation is performed using the above formulas (4)-(5), and the results are as follows: The dynamic stiffness k of the shock absorber in the horizontal direction is x =9892.8 (N·m), structural loss factor of shock absorber in horizontal direction g x =0.1464.

[0083] Specifically, in the above test case: the acceleration sensor used is the 356A01 model produced by the American PCB company; the hammer used is the 086C03 model produced by the American PCB company; the data acquisition device used is the eight-channel data acquisition device of Siemens LMS, model SCM2E02; the test software used is the Testlab2018 version of Siemens LMS.

[0084] According to the above description, in this embodiment, the load-bearing capacity of the shock absorber in the test state is 5.69% lower than that in the working state. If the accuracy requirement is very high, the mass of the mass block assembly can be increased so that the load-bearing capacity of the shock absorber in the test state is slightly greater than that in the working state, and then the test is performed again according to the above method. After the dynamic stiffness and structural loss factor of the shock absorber under two different loads are obtained through testing, the dynamic stiffness and structural loss factor corresponding to the load-bearing capacity in the working state can be obtained by interpolation.

[0085] The above contents are only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention made by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper, characterized in that: The steps include: S1: Use n identical shock absorbers to support a mass assembly, where n ≥ 3, and the positions of the n shock absorbers should satisfy: the gravity of the mass assembly is evenly distributed to the n shock absorbers; S2: installing a plurality of acceleration sensors on the mass assembly; S3: Excite the mass block assembly by using a hammer method or a shaker method. During the test, multiple excitation points are excited in sequence to obtain a frequency response function; S4: converting the frequency response function obtained in step S3 to the center of mass of the mass block assembly to obtain the center of mass Z degree of freedom origin frequency response function and the center of mass RZ degree of freedom origin frequency response function; S5: The dynamic stiffness and structural loss factor of the shock absorber in the vertical direction are calculated by the frequency response function of the center of mass Z degree of freedom origin; the dynamic stiffness and structural loss factor of the shock absorber in the horizontal direction are calculated by the frequency response function of the center of mass RZ degree of freedom origin.

2. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 1, characterized in that: In step S2, the number of acceleration test channels N on the mass block assembly is ≥6, and in the frequency response function test of S3, these N acceleration test channels are recorded simultaneously; in step S3, the number of excitation points M on the mass block assembly is ≥6.

3. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 2, characterized in that: In step S4, the formula used to convert the frequency response function obtained by the test to the centroid is: In formula (1), H is an N×M matrix composed of the frequency response functions obtained by the test, each column corresponds to an excitation point, and each row corresponds to an acceleration test channel; The 6×6 matrix is ​​composed of the frequency response function of the center of mass. The third diagonal element is the frequency response function of the center of mass Z degree of freedom origin, and the sixth diagonal element is the frequency response function of the center of mass RZ degree of freedom origin; the superscript T represents the transpose operation of the matrix, and the superscript -1 represents the inverse operation of the matrix; T a is the acceleration transformation matrix, T f is the excitation transformation matrix, and their specific expressions are as follows: In T a , T f In the expressions of these two matrices: is the coordinate of the center of mass of the mass block assembly; (x i ,y i ,z i ) is the coordinate of the ith channel acceleration sensor, {d xi ,d yi ,d zi } T is the unit vector along the acceleration test direction of the i-th channel; (x ′ k ,y ′ k ,z ′ k ) is the coordinate of the kth excitation point, {d ′ xk ,d ′ yk ,d ′ zk } T is the unit vector along the excitation direction of the kth excitation point.

4. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 1, characterized in that: In step S5, the center of mass Z degree of freedom origin frequency response function The maximum amplitude and its corresponding angular frequency ω 33,p Calculate the dynamic stiffness k of the shock absorber in the vertical direction z and structural loss factor g z , the formula used is: Frequency response function of the origin of the center of mass RZ degree of freedom The maximum amplitude and its corresponding angular frequency ω 66,p Calculate the dynamic stiffness k of the shock absorber in the horizontal direction x and structural loss factor g x , the formula used is: In formula (2) to formula (5), n is the number of shock absorbers used in the test device; m is the total mass supported by n shock absorbers; I z is the moment of inertia of the mass block assembly about the vertical center line passing through its center of mass; the center of mass of each of the n shock absorbers has a distance value from the vertical line passing through the center of mass of the mass block assembly, and r is the average of these n distance values.

5. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 4, characterized in that: Before calculating the dynamic stiffness and structural loss factor in the vertical and horizontal directions, the peak of the amplitude-frequency curve of the frequency response function of the origin of the center of mass Z degree of freedom is calculated. The peak of the amplitude-frequency curve of the frequency response function of the origin of the mass center RZ degree of freedom The corrected vertex is the intersection of the extension line of the line connecting the two points on its left side and the extension line of the line connecting the two points on its right side, and the height of the corrected vertex is greater than all the original data points.

6. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 1, characterized in that: The test is performed using a test device, which includes a shock absorber test installation assembly, an acceleration sensor, an exciter, and a data acquisition system; the acceleration sensor and the exciter are respectively connected to the data acquisition system; The shock absorber test installation assembly comprises a base and a mass block assembly, and the shock absorber is installed between the mass block assembly and the base; a plurality of acceleration sensors are installed on the mass block assembly to monitor the six degrees of freedom of movement of the mass block assembly.

7. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 6, characterized in that: The exciter is a force hammer or a vibration exciter.

8. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 6, characterized in that: The mass block assembly comprises a polygonal bottom plate and a mass block fixedly connected to the polygonal bottom plate.

9. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration damper according to claim 8, characterized in that: The mass block includes one or more mass stacking blocks, and the mass stacking blocks are detachably fixedly connected to the polygonal bottom plate.

10. The method for testing the dynamic stiffness and structural loss factor of an axisymmetric vibration absorber according to any one of claims 6 to 9, characterized in that: The vibration damper test installation assembly also includes a connection structure, which includes an upper connection piece and a lower connection piece, the upper connection piece is fixedly connected to the mass assembly, the lower connection piece is fixedly connected to the base, and the vibration damper is installed between the upper connection piece and the lower connection piece.

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