A method and system for rapid testing of local static stiffness of mechanical structures

Abstract

The present invention provides a method and system for rapid testing of local static stiffness of a mechanical structure, so as to improve the problem of poor versatility of existing local position stiffness testing of mechanical structures. The method comprises: installing a mechanical component to be tested and placing it in a free boundary state; determining a local test point and installing a vibration acceleration sensor at the local test point; using a modal force hammer to perform hammer tests on the local test point along the X, Y, and Z directions respectively, and obtaining the corresponding vibration acceleration frequency response function signal data of the local test point; importing the vibration acceleration frequency response function signal data into a modal analysis system, and identifying the modal information parameters of the vibration acceleration frequency response function signal data; performing data processing on the modal information parameters to obtain a modal comprehensive curve; integrating the modal comprehensive curve twice to obtain a dynamic flexibility curve; obtaining the values ​​of the responses in the X, Y, and Z directions at 0 Hz based on the dynamic flexibility curve, and calculating the static stiffness values ​​of the local test point in the X, Y, and Z directions.

Description

Technical Field

[0001] The invention relates to the field of mechanical structure mechanical property detection, and in particular to a method and system for rapid testing of local static stiffness of a mechanical structure. Background Art

[0002] The static stiffness of the whole or local installation point of the mechanical structure is an important parameter to characterize the mechanical characteristics of the structure. Identifying and controlling this parameter is crucial to improving the engineering mechanical properties of the mechanical structure. In the field of mechanical / automotive engineering, the size of the structural stiffness directly reflects the robustness of the system and has a direct impact on the stress and strain under load. Inadequate design and verification of the static stiffness of the mechanical structure will bring huge challenges to the durability and abnormal noise control of the structure and even the system. However, the traditional static stiffness test method of mechanical structure is very complicated. It is necessary to build a special bench for stiffness testing, use a special force loading device and assist with a special fixture, and the range of the force loading device limits the scope of application of the system. As recorded in the Chinese patent with application number CN202011599069.2 and the name of "A Method for Testing Torsional Stiffness of Automobile Front Hood", it is necessary to build a special component stiffness test bench, a special force loading device and device to load, arrange displacement sensors to measure displacement, and then calculate the static stiffness of the structure through the test results. The test preparation and testing process are relatively complicated, the work efficiency is low, and the operational reproducibility of the tests between different components is poor. Moreover, the existing testing methods remain at the dedicated testing stage, that is, if the object to be tested changes, the devices and equipment required for the test will also change accordingly. Not only do they rely on dedicated test benches, dedicated loading devices and test accuracy, but the test accuracy is often affected by sensors, and the structural displacement test characterization is relatively complicated. Summary of the invention

[0003] In view of the above shortcomings of the prior art, an object of the present invention is to provide a method and system for quickly testing the local static stiffness of a mechanical structure, so as to improve the problem of poor versatility of the existing local stiffness testing of mechanical structures.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for rapid testing of local static stiffness of a mechanical structure, comprising the following process:

[0005] Install the mechanical component to be tested and put it in a free boundary state;

[0006] Determine a local test point and install a vibration acceleration sensor at the local test point;

[0007] Using a modal hammer to perform hammer tests on the local test points along the X, Y, and Z directions, respectively, and obtaining corresponding vibration acceleration frequency response function signal data of the local test points;

[0008] Importing the vibration acceleration frequency response function signal data into a modal analysis system to identify modal information parameters of the vibration acceleration frequency response function signal data;

[0009] Performing data fitting processing on the modal information parameters to obtain a modal comprehensive curve;

[0010] The dynamic flexibility curve is obtained by integrating the modal composite curve twice;

[0011] Based on the dynamic flexibility curve, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated.

[0012] In one embodiment of the method for rapid testing of local static stiffness of a mechanical structure of the present invention, the data fitting process also includes a process of eliminating the rigid body mode of the free system and the influence of the upper residual.

[0013] In one embodiment of the method for rapid testing local static stiffness of a mechanical structure of the present invention, after the vibration acceleration frequency response function signal data is imported into a modal analysis system, modal analysis technology is used to identify modal information parameters of the vibration acceleration frequency response function signal data.

[0014] In one embodiment of the method for rapid testing local static stiffness of a mechanical structure of the present invention, during the data fitting process, modal information parameters that can highly characterize the low-frequency frequency response characteristics of the test location are selected for fitting by means of modal synthesis technology.

[0015] In one embodiment of the method for rapid testing of local static stiffness of a mechanical structure of the present invention, the mechanical component to be tested is suspended by an elastic rope so as to be in a free boundary state.

[0016] In one embodiment of the method for rapid testing of local static stiffness of a mechanical structure of the present invention, the mechanical component to be tested is mounted on an elastic structure so that it is in a free boundary state.

[0017] In an embodiment of the method for rapid testing local static stiffness of a mechanical structure of the present invention, the elastic structure is an air spring.

[0018] In one embodiment of the method for rapid testing the local static stiffness of a mechanical structure of the present invention, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained based on the dynamic flexibility curve, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated. Specifically, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained based on the dynamic flexibility curve, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated using the inverse relationship.

[0019] The present invention also provides a rapid testing system for local static stiffness of a mechanical structure, comprising: an elastic mounting structure, an acceleration sensor, a modal force hammer and a data processing unit. The elastic mounting structure is used to mount the mechanical component to be tested and keep it in a free boundary state; the acceleration sensor is mounted on a test point on the mechanical component to be tested; the modal force hammer is used to strike the test point; the data processing unit has a first signal input port electrically connected to a signal output end of the modal force hammer, and a second signal input port electrically connected to a signal output end of the acceleration sensor.

[0020] In an embodiment of the system for rapid testing local static stiffness of a mechanical structure of the present invention, the elastic mounting structure includes at least three elastic ropes that can suspend the mechanical component to be tested.

[0021] In an embodiment of the local static stiffness rapid testing system of a mechanical structure of the present invention, the elastic mounting structure includes at least three air spring supporting legs that can support the mechanical component to be tested.

[0022] In one embodiment of the local static stiffness rapid testing system of a mechanical structure of the present invention, the data processing unit includes a computer, a low-pass filter module, an A / D conversion module and a Fourier transformation module.

[0023] In summary, the method and system for rapid testing of local static stiffness of mechanical structures of the present invention have the following beneficial effects:

[0024] 1. The mechanical components to be tested only need to meet the boundary conditions of the modal response test method, and there is no need to design a special test bench.

[0025] 2. The stiffness information of the local test point of the mechanical component to be tested is obtained by hitting the point with a modal force hammer and processing the response signal of the vibration acceleration pickup arranged at the location, without the need for a special loading system and fixture.

[0026] 3. The identification of the final stiffness value of the mechanical component to be tested integrates classical vibration signal processing technologies such as modal analysis technology, signal processing technology, and vibration dynamics theory. The method has clear theory, mature technology, high reliability, and can avoid uncertain and uncontrollable factors such as position error and measurement point error of traditional testing technology.

[0027] 4. The method and system for rapid testing of local static stiffness of mechanical structures of the present invention do not rely on special stands, special loading systems and fixtures, are convenient and easy to operate, are not restricted by the work site and test environment, and have strong technical versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be 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 work.

[0029] Figure 1 It is a schematic diagram of a flow chart of an embodiment of a method for rapid testing of local static stiffness of a mechanical structure according to the present invention;

[0030] Figure 2 The figure is a theoretical model diagram of the method for rapid testing the local static stiffness of a mechanical structure of the present invention;

[0031] Figure 3 The figure is a simplified structural diagram of an embodiment of a system for rapid testing local static stiffness of a mechanical structure according to the present invention.

[0032] Component number description

[0033] 100, elastic mounting structure; 200, acceleration sensor; 300, modal force hammer; 400, data processing unit; 401, filter conversion processing unit; 402, frequency response function processing unit; 403, computer; 500, mechanical component to be tested. DETAILED DESCRIPTION

[0034] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0035] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0036] See also Figures 1 to 3 The present invention provides a method and system for rapid testing of local static stiffness of a mechanical structure. The testing method utilizes a vibration modal response testing method, with the aid of a commonly used vibration acceleration sensor, and adopts a hammer test to obtain the local vibration frequency response of the structure, and then identifies the testing method of the structural point stiffness. The method does not require the design of a special bench, a special loading device, or an auxiliary fixture for the object to be tested. The stiffness identification method is derived from traditional modal testing technology, has high technical maturity, is convenient to operate, is not limited by the work site and the test environment, has strong technical versatility, and is low-cost. It can effectively improve the existing local stiffness testing of mechanical structures, which has poor versatility and the problem that the test accuracy is restricted by the sensor.

[0037] like Figure 1 As shown, Figure 1 The flowchart of one embodiment of the method for rapid testing the local static stiffness of a mechanical structure of the present invention is as follows. The method for rapid testing the local static stiffness of a mechanical structure comprises the following steps:

[0038] S1. Install the mechanical component to be tested and put it in a free boundary state. In this step, as long as it can be in a free boundary state, the installation method of the mechanical component to be tested is not limited. For example, in one embodiment of the present invention, the mechanical component to be tested is suspended by an elastic rope to ensure that the mechanical component to be tested is in a free boundary state. The elastic rope can be a spring, an elastic soft rope or other components. In another embodiment of the invention, the mechanical component to be tested is propped up by an elastic structure support to ensure that the mechanical component to be tested is in a free boundary state. The elastic structure can be a supporting structure such as a spring, an elastomer or an air spring. It should be noted that in order to ensure the stability of the mechanical component to be tested in the free boundary state, the number of elastic rope suspension points or spring support points should be at least three.

[0039] S2. Determine the local test point and install the vibration acceleration sensor at the local test point. In this step, after the local test point is determined, the vibration acceleration sensor can be installed. Considering the need to tap the local test point later, in one example of the present invention, the vibration acceleration sensor is installed on the other side opposite to the tapping point. The installation method of the vibration acceleration sensor is not limited. In order not to damage the mechanical component to be tested, in one embodiment of the present invention, the vibration acceleration sensor is installed on the other side opposite to the tapping point by bonding or adsorption. In order to ensure that the X, Y, and Z directions can be effectively tapped to obtain the X, Y, and Z directions The vibration frequency response function, a simple auxiliary test fixture can be appropriately added according to the local characteristics of the mechanical structure, such as various types of lightweight and high-rigidity bushings, pads, etc. After the various connecting parts are connected, the system is debugged according to the vibration frequency response test requirements.

[0040] S3. Perform hammer tests on the local test points along the X, Y, and Z directions using a modal hammer, and obtain the corresponding vibration acceleration frequency response function signal data of the local test points. In this step, perform hammer tests on the local test points along the X, Y, and Z directions using a modal hammer, and obtain the corresponding vibration acceleration frequency response function signal data of the local test points by collecting the signals of the vibration acceleration sensor. When collecting the signals of the vibration acceleration sensor, wired or wireless collection can be used, and the type of vibration acceleration sensor can be flexibly selected, which is not limited here.

[0041] S4. Import the vibration acceleration frequency response function signal data into the modal analysis system to identify the modal information parameters of the vibration acceleration frequency response function signal data. In this step, the modal analysis system MAS (Modal Analysis System) can build a modal analysis system integrating structural modeling, vibration data acquisition, modal identification, and dynamic stiffness testing based on hammering method, sine slow scanning method, sine fast scanning, random excitation method, etc. The software is comprehensive in function, easy to use, easy to maintain, and has a user-friendly interface. After the vibration acceleration frequency response function signal data is imported into the modal analysis system, the modal information parameters of the vibration acceleration frequency response function signal data are identified using modal analysis technology.

[0042] S5. Perform data fitting processing on the modal information parameters to obtain a modal synthesis curve. In this step, considering the accuracy of the data, in one embodiment of the method for rapid testing the local static stiffness of a mechanical structure of the present invention, the data fitting process also includes a process of eliminating the influence of the free system rigid body mode and the upper residual. After eliminating the influence of the system rigid body mode and the upper residual, the modal synthesis technology is used to select a response curve that can highly characterize the low-frequency frequency response characteristics of the test location to obtain a modal synthesis curve.

[0043] S6. Integrate the modal comprehensive curve twice to obtain a dynamic compliance curve. In this step, the two integrations of the modal comprehensive curve can be implemented by a computer.

[0044] S7, based on the dynamic flexibility curve, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated. In an embodiment of the method for rapid testing the local static stiffness of a mechanical structure of the present invention, in this step, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained based on the dynamic flexibility curve, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated using the inverse relationship.

[0045] The theoretical basis for obtaining the static stiffness value of the mechanical structure in the method of the present invention is as follows:

[0046] like Figure 2 The figure shows the theoretical model diagram of the local static stiffness rapid test method of the mechanical structure of the present invention. For a single degree of freedom vibration dynamics system, according to the classical vibration dynamics theory, the structural vibration equation is obtained as follows:

[0047]

[0048] Where M is the system mass, C is the system structural damping coefficient, K is the system stiffness; x is the vibration response displacement under excitation F.

[0049] Therefore, through Fourier transform, the frequency response (dynamic flexibility) expression function of the system under excitation F can be obtained:

[0050]

[0051] The dynamic stiffness can be derived based on formula (2):

[0052] K(jω)=-Mω 2 +iCω+K (3)

[0053] It can be seen from formula (3) that when the frequency ω is 0 Hz, the dynamic stiffness of the structure is equal to the static stiffness K. Therefore, by obtaining the amplitude of the dynamic stiffness at 0 Hz at a certain local position of the structure through experiments, the static stiffness of the local structure can be indirectly obtained.

[0054] like Figure 3 As shown, Figure 3The structure diagram of one embodiment of the local static stiffness rapid testing system of the mechanical structure of the present invention. The present invention also provides a local static stiffness rapid testing system of the mechanical structure, comprising: an elastic mounting structure 100, an acceleration sensor 200, a modal force hammer 300 and a data processing unit 400. The elastic mounting structure 100 is used to mount the mechanical component 500 to be tested and keep it in a free boundary state; the acceleration sensor 200 is mounted on the test point on the mechanical component 500 to be tested, and in order to ensure the knocking position, it can be set on the other side relative to the knocking point, for example; the modal force hammer 300 is used to knock the test point; the data processing unit 400 has a first signal input port electrically connected to the signal output end of the modal force hammer 300, and a second signal input port electrically connected to the signal output end of the acceleration sensor 200. In one embodiment of the local static stiffness rapid testing system of the mechanical structure of the present invention, the data processing unit includes a computer 403, a filter conversion processing unit 402 and a frequency response function processing unit 401. The filter conversion processing unit 402 includes a low-pass filter module, an A / D conversion module and a Fourier transform module. It is understandable that the filter conversion processing unit 402 and the frequency response function processing unit 401 can also be directly set in the computer 403. The above-mentioned mechanical structure local static stiffness rapid test system can realize the rapid test of the local static stiffness of various mechanical components to be tested, with strong versatility and high test accuracy.

[0055] In the local static stiffness rapid testing system of the mechanical structure of the present invention, the elastic mounting structure can be any suitable structure that can install the mechanical component to be tested in a free boundary state. In one embodiment of the local static stiffness rapid testing system of the mechanical structure of the present invention, the elastic mounting structure includes at least three elastic ropes that can suspend the mechanical component to be tested, and the mechanical component to be tested is suspended by the elastic ropes to ensure that the mechanical component to be tested is in a free boundary state. In one embodiment of the local static stiffness rapid testing system of the mechanical structure of the present invention, the elastic mounting structure includes at least three air spring support legs that can support the mechanical component to be tested, and the mechanical component to be tested is supported by the air spring support legs to ensure that the mechanical component to be tested is in a free boundary state.

[0056] It should be noted that the modal hammer is an important tool for solving structural dynamics and mechanical vibration problems, conducting resonance detection, test design, and modal testing. It is widely used and its specific structure will not be described in detail here.

[0057] In summary, the local static stiffness rapid testing method and system of the mechanical structure of the present invention have the following beneficial effects: 1. The mechanical component to be tested only needs to meet the boundary conditions of the modal response test method, and there is no need to design a special bench. 2. The stiffness information of the local test point of the mechanical component to be tested is obtained by hitting the point with a modal force hammer and processing the vibration acceleration pickup response signal arranged at the place, without the need to use special loading equipment and fixtures. 3. The final stiffness value identification of the mechanical component to be tested integrates classical vibration signal processing technologies such as modal analysis technology, signal processing technology, and vibration dynamics theory. The method theory is clear, the technology is mature, and the reliability is high. It can avoid the uncertain and uncontrollable factors such as position error and measurement point error of traditional testing technology. 4. The local static stiffness rapid testing method and system of the mechanical structure of the present invention do not rely on special benches, special loading equipment and fixtures, are convenient to operate, are not limited by the work site and test environment, and have strong technical versatility. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for rapid testing of local static stiffness of a mechanical structure, characterized in that: The process includes: Install the mechanical component to be tested and put it in a free boundary state; Determine a local test point, and install a vibration acceleration sensor on the other side opposite to the local test point; Using a modal hammer to perform hammer tests on the local test points along the X, Y, and Z directions, respectively, and obtaining corresponding vibration acceleration frequency response function signal data of the local test points; Importing the vibration acceleration frequency response function signal data into a modal analysis system to identify modal information parameters of the vibration acceleration frequency response function signal data; Performing data fitting processing on the modal information parameters to obtain a modal comprehensive curve; The dynamic flexibility curve is obtained by integrating the modal composite curve twice; Based on the dynamic flexibility curve, the values ​​of the responses in the X, Y, and Z directions at 0 Hz are obtained, and the static stiffness values ​​of the local test point in the X, Y, and Z directions are calculated; The data fitting process also includes the process of eliminating the rigid body mode of the free system and the influence of the upper residual error; After the vibration acceleration frequency response function signal data is imported into the modal analysis system, the modal analysis technology is used to identify the modal information parameters of the vibration acceleration frequency response function signal data.

2. The method for rapid testing of local static stiffness of a mechanical structure according to claim 1, characterized in that: In the process of data fitting, modal information parameters that can highly characterize the low-frequency frequency response characteristics of the test location are selected for fitting with the help of modal synthesis technology.

3. The method for rapid testing local static stiffness of a mechanical structure according to claim 1, characterized in that: The mechanical component to be tested is suspended by an elastic rope to be in a free boundary state.

4. The method for rapid testing of local static stiffness of a mechanical structure according to claim 1, characterized in that: The mechanical component to be tested is mounted on an elastic structure so that it is in a free boundary state.

5. The method for rapid testing of local static stiffness of a mechanical structure according to claim 4, characterized in that: The elastic structure is an air spring.

6. The method for rapid testing of local static stiffness of a mechanical structure according to claim 1, characterized in that: The method of obtaining the values ​​of the responses in the X, Y, and Z directions at 0 Hz based on the dynamic flexibility curve and calculating the static stiffness values ​​of the local test point in the X, Y, and Z directions is specifically as follows: obtaining the values ​​of the responses in the X, Y, and Z directions at 0 Hz based on the dynamic flexibility curve, and calculating the static stiffness values ​​of the local test point in the X, Y, and Z directions by using the inverse relationship.

7. A rapid testing system for local static stiffness of a mechanical structure, characterized in that: include: An elastic mounting structure, used for mounting the mechanical component to be tested and keeping it in a free boundary state; An acceleration sensor is installed at a test point on the mechanical component to be tested; A modal force hammer, used for striking the test point; A data processing unit has a first signal input port electrically connected to a signal output end of the modal hammer, and a second signal input port electrically connected to a signal output end of the acceleration sensor.

8. The mechanical structure local static stiffness rapid testing system according to claim 7, characterized in that: The elastic mounting structure includes an elastic rope for suspending the mechanical component to be tested.

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