Method and system for obtaining test duration of equivalent vibration test of loose parts

Abstract

The present invention provides a method and system for obtaining the test duration of an equivalent vibration test of a loose part. Based on the finite element model of the loose part, the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load is obtained by means of modal analysis and random vibration analysis; time history analysis is performed on the acceleration power spectral density function to obtain acceleration amplitude statistical data; the equivalent test time is obtained based on the acceleration amplitude statistical data according to the linear damage theory. The method of the present invention does not need to obtain the actual vibration response through a fluid-induced vibration test, solves the problem that it is difficult to obtain the actual vibration response in the equivalent vibration test technology, reduces the economic cost and time cost, and ensures the conservatism of the equivalent vibration test.

Description

Technical Field

[0001] The present invention belongs to the technical field of equivalent vibration testing, and particularly relates to a method and system for obtaining the test duration of equivalent vibration testing for loose parts. Background Art

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Connectors such as screws and nuts may become loose or detached under the continuous impact of fluid loads. During the design or modification of connectors, vibration tests are required to verify their anti-loosening performance. In the actual use process of connectors, they often need to serve for a long time. For example, in nuclear power plants, most of them need to meet a service life of sixty years. It is obviously unrealistic to verify the anti-loosening performance of connectors by simulating the actual test method. Therefore, an equivalent technology of vibration testing, that is, a technology that simulates actual vibration by accelerating vibration, is needed to shorten the test duration. However, the required duration of the equivalent test needs to be obtained based on the fatigue and cumulative damage theory after obtaining the actual vibration response data of the component under the fluid-induced vibration load. This test data often needs to be obtained by using sensors through fluid-induced vibration tests. The test is difficult and requires a large test cost, which brings difficulties to the practical application of the equivalent vibration testing technology. Summary of the Invention

[0004] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a method and system for obtaining the test duration of equivalent vibration testing for loose parts. Based on the finite element model of the loose part, the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load is obtained by using modal analysis and random vibration analysis. The equivalent duration is solved based on the acceleration power spectral density function, without obtaining the actual response of the position of the loose part under the fluid-induced vibration load through sensors, thus solving the problem that it is difficult to obtain the actual vibration response in the equivalent vibration testing technology.

[0005] To achieve the above object, the first aspect of the present invention provides a method for obtaining the test duration of equivalent vibration testing for loose parts, including:

[0006] Establish a fluid calculation model of the loose part, and obtain fluid physical parameters according to the established fluid calculation model;

[0007] Calculate the fluid-induced vibration load received by the loose part based on the obtained physical parameters according to the fluid-induced vibration theory;

[0008] Based on the finite element model of the loose part, obtain the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load by using modal analysis and random vibration analysis;

[0009] Perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data;

[0010] Based on the acceleration amplitude statistical data, obtain the equivalent test time based on the linear damage theory, and conduct an equivalent test on the loose parts.

[0011] The second aspect of the present invention provides a test duration acquisition system for equivalent vibration test of loose parts, including:

[0012] Fluid calculation module establishment module: Establish a fluid calculation model of the loose parts, and obtain fluid physical parameters according to the established fluid calculation model;

[0013] Calculation module: Calculate the fluid-induced vibration load received by the loose parts based on the obtained physical parameters according to the fluid-induced vibration theory;

[0014] First analysis module: Based on the finite element model of the loose parts, obtain the acceleration power spectral density function of the response of the loose parts under the fluid-induced vibration load by means of modal analysis and random vibration analysis;

[0015] Second analysis module: Perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data;

[0016] Test module: Based on the acceleration amplitude statistical data, obtain the equivalent test time based on the linear damage theory, and conduct an equivalent test on the loose parts.

[0017] The third aspect of the present invention provides a computer device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device runs, the processor communicates with the memory through the bus. When the machine-readable instructions are executed by the processor, a test duration acquisition method for equivalent vibration test of loose parts is executed.

[0018] The fourth aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is run by a processor, a test duration acquisition method for equivalent vibration test of loose parts is executed.

[0019] The above one or more technical solutions have the following beneficial effects:

[0020] In the present invention, based on the finite element model of the loose part, the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load is obtained by means of modal analysis and random vibration analysis; time history analysis is performed on the acceleration power spectral density function to obtain acceleration amplitude statistical data; based on the acceleration amplitude statistical data, the equivalent test time is obtained according to the linear damage theory; it is not necessary to obtain the actual vibration response through a fluid-induced vibration test, solving the problem that it is difficult to obtain the actual vibration response in the equivalent vibration test technology, reducing the economic cost and time cost, and ensuring the conservativeness of the equivalent vibration test.

[0021] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] Figure 1 is the logic flow chart for obtaining the test duration of the fluid-induced vibration acceleration test of the loose part in Embodiment 1 of the present invention;

[0024] Figure 2 is the fluid calculation finite element model of the steam generator in Embodiment 1 of the present invention;

[0025] Figure 3 is the power spectral density curve of the fluid-induced vibration load at the tube sheet position of the steam generator in Embodiment 1 of the present invention;

[0026] Figure 4 is the finite element model of the tube sheet of the steam generator in Embodiment 1 of the present invention;

[0027] Figure 5 is the acceleration power spectral density curve at the position of the tube sheet connecting piece under the fluid-induced vibration load in Embodiment 1 of the present invention;

[0028] Figure 6 is the acceleration time history curve at the position of the tube sheet connecting piece under the fluid-induced vibration load in Embodiment 1 of the present invention;

[0029] Figure 7 is the amplitude statistical result of the acceleration in Embodiment 1 of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0032] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] Embodiment 1

[0034] This embodiment discloses a method for obtaining the test duration of an equivalent vibration test of a loose part, including:

[0035] Establish a fluid calculation model of the loose part, and obtain fluid physical parameters according to the established fluid calculation model;

[0036] Calculate the fluid-induced vibration load received by the loose part based on the fluid-induced vibration theory according to the obtained physical parameters;

[0037] Based on the finite element model of the loose part, obtain the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load by using modal analysis and random vibration analysis methods;

[0038] Perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data;

[0039] Obtain the equivalent test time based on the linear damage theory according to the acceleration amplitude statistical data, and perform an equivalent test on the loose part.

[0040] As Figure 1 shown, in this embodiment, a method for obtaining the test duration of an equivalent vibration test of a loose part specifically includes:

[0041] S101: Establish a CAE fluid calculation finite element model, obtain physical parameters of the flow field near the component, such as flow velocity, density, and void fraction, and then use the classical empirical formula method of fluid-induced vibration theory to obtain the turbulent pressure pulsation power spectral density curve on the surface of the component as the fluid-induced vibration load received by the component;

[0042] S102: Establish a finite element model of the component, use random vibration analysis to calculate the response of the component under the fluid-induced vibration load, and obtain the acceleration power spectral density function at the position of the connecting piece;

[0043] S103: Use the method of solving the time history Fourier spectrum corresponding to the power spectral density, and then performing inverse Fourier transform after superimposing random phases to convert the acceleration power spectral density function at the position of the connecting piece into time history data;

[0044] S104: Obtain the amplitude statistical data of acceleration by using the mean crossing peak counting method. After obtaining the amplitude statistical data of acceleration, based on the linear cumulative fatigue damage theory, the vibration test time required to generate the same damage under the given test acceleration and frequency can be calculated for equivalent tests.

[0045] The following takes calculating the acceleration amplitude statistical data at the position of the steam generator tube sheet connection part by using the method of this embodiment as an example to support the transformation of the steam generator tube sheet connection part for illustration.

[0046] In step S101, use computational fluid dynamics software (such as Star CCM+ etc.) to establish a fluid calculation model of the steam generator, such as Figure 2 , to obtain the physical parameters of the flow field near the tube sheet, such as flow velocity, density, void fraction, etc. Use classical empirical formulas such as the von Karman formula, combined with physical information such as the geometric dimensions of the tube sheet, to obtain the power spectral density curve of the turbulent pressure pulsation on the component surface as the fluid-induced vibration load on the tube sheet, such as Figure 3 .

[0047] In step S102, use finite element software to calculate the response of the tube sheet under the fluid-induced vibration load obtained in S101. The specific steps are as follows:

[0048] Step S102-1: As Figure 4 shown, establish a finite element model in the finite element software according to the physical information such as the geometric dimensions, boundary conditions, and material properties of the tube sheet;

[0049] Step S102-2: Conduct modal analysis, analyze a sufficient number of modal orders to ensure that the highest modal frequency of the highest order can be greater than the highest frequency of the power spectral density function of the fluid-induced vibration load;

[0050] Step S102-3: As Figure 5 shown, apply the fluid-induced vibration load in the finite element model, and after performing ANSYS finite element calculation using random vibration analysis in spectral analysis, obtain the acceleration power spectral density function of the response under the fluid-induced vibration load at the position of the tube sheet connection part;

[0051] As Figure 6 shown, in step S103, convert the acceleration power spectral density function obtained in S102 into acceleration time history information by the method of solving the time history Fourier spectrum corresponding to the power spectral density and then performing inverse Fourier transform after superposing random phases. The specific method is as follows:

[0052] In the calculation, Appendix B of 3.7.1(2014) in the U.S. NUCLEAR REGULATORY COMMISSION STANDARD REVIEW PLAN (SRP) is adopted, and the Fourier amplitude is calculated from the initial PSD function:

[0053]

[0054] In the formula, F(ω) is the Fourier amplitude; ω is the circular frequency; S 0 (ω) is the initial PSD function; T D is the strong earthquake duration.

[0055] Taking the acceleration power spectral density function of the response under the fluid-induced vibration load obtained above as S 0 (ω) and substituting it into the above formula, the corresponding Fourier amplitude F(ω) is calculated. Based on the above Fourier amplitude and random phase angle, a Fourier spectrum is constructed, and an artificial time history is obtained by inverse Fourier transform.

[0056] In step S104, the acceleration time history information obtained in S103 is processed by the "mean crossing peak counting" method, that is, by obtaining the mean value of the acceleration in the time history information. In the time history curve, as time changes, every time the acceleration value equals the mean value twice, a peak and a trough can be obtained. Recording the magnitudes and quantities of all peaks and troughs and performing statistics can obtain Figure 7 the acceleration amplitude statistical data shown, which can be used for the equivalent technology of vibration tests to obtain the required duration of the equivalent test. The method for obtaining the required duration of the equivalent test is as follows:

[0057] This equivalent method is based on the linear damage theory. If the stress amplitude S of the actual vibration i corresponds to the number of cycles n i when, the equivalent stress amplitude S c that produces the same damage is:

[0058]

[0059] In the formula: 1 / b is the slope of the material design fatigue curve of the test piece on the double logarithmic coordinate, and i is the number of points in the amplitude statistical program.

[0060] Let N c =∑n i , corresponding to the actual structure under consideration, we can get:

[0061] The material design fatigue curve S-N can be written as:

[0062] Further rewritten as:

[0063] It can be proved that the stress is proportional to the acceleration. Then, for the acceleration, the following formula holds:

[0064]

[0065] Then the equivalent acceleration g e corresponds to the equivalent occurrence times N e is:

[0066]

[0067] where the subscript c represents the known points on the S-N curve, the subscript e represents the conditions directly or indirectly related to the load e (the load in the equivalent test), N 实i and g 实i are the actual number of vibration cycles and the actual vibration acceleration.

[0068] According to the settings of the equivalent vibration test (i.e., the frequency and acceleration amplitude of the vibration table), the equivalent duration can be obtained. The result obtained by applying this method is that the equivalent test with 156 hours, 30 Hz, and 20 g acceleration amplitude can be equivalent to the fluid-induced vibration load suffered by the tube sheet connection for 60 years.

[0069] Use the method of this embodiment to calculate the statistical data of the acceleration amplitude at the position of the basket connection of the in-core structure, and compare it with the statistical data of the acceleration amplitude at this position in the fluid-induced vibration test to ensure the conservativeness of this method.

[0070] Specifically, using computational fluid dynamics software (such as Fluent, etc.), establish a fluid calculation model of the basket connection to obtain the physical parameters of the flow field near the basket connection, such as flow velocity, density, void fraction, etc. Using classical empirical formulas such as the von Karman formula, combined with physical information such as the geometric dimensions of the basket connection, calculate the power spectral density function of the fluid-induced vibration load suffered by the basket connection.

[0071] In step S102, use finite element software to calculate the response of the basket connection under the fluid-induced vibration load obtained in S101. The specific steps are as follows:

[0072] Step S102-1: Establish a finite element model in the finite element software according to the physical information such as the geometric dimensions, boundary conditions, and material properties of the basket.

[0073] Step S102-2: Conduct a modal analysis, analyze a sufficient number of modal orders to ensure that the highest modal frequency of the first order can be greater than the highest frequency of the power spectral density function of the fluid-induced vibration load.

[0074] Step S102-3: Apply fluid-induced vibration load to the model. After performing finite element calculations using random vibration analysis in spectral analysis, obtain the acceleration power spectral density function at the position of the hanging basket connection member;

[0075] In step S103, convert the acceleration power spectral density function obtained in S102 into acceleration time history information by solving the time history Fourier spectrum corresponding to the power spectral density and then performing an inverse Fourier transform after superimposing random phases, as shown in the appendix Figure 6 .

[0076] In the calculation, use Appendix B in U.S. NUCLEAR REGULATORY COMMISSION STANDARD REVIEW PLAN (SRP) 3.7.1(2014) to calculate the Fourier amplitude from the initial PSD function:

[0077]

[0078] In the formula, F(ω) is the Fourier amplitude; ω is the circular frequency; S 0 (ω) is the initial PSD function; T D is the strong earthquake duration.

[0079] Substitute the acceleration power spectral density function of the response as S 0 (ω) into the above formula, calculate the corresponding Fourier amplitude F(ω), construct a Fourier spectrum based on the above Fourier amplitude and random phase angle, and obtain an artificial time history by inverse Fourier transform.

[0080] Construct a Fourier spectrum based on the above Fourier amplitude and random phase angle, and obtain an artificial time history by inverse Fourier transform.

[0081] In step S104, use the mean crossing peak counting method for the acceleration time history information obtained in S103, that is, by obtaining the mean value of the acceleration in the time history information. In the time history curve, as time changes, every time the acceleration value equals the mean twice, a peak and a trough can be obtained. Record the magnitudes and quantities of all peaks and troughs and perform statistics. This data can be used for the equivalent technology of vibration tests to obtain the duration required for equivalent tests.

[0082] The specific method for obtaining the duration required for equivalent tests is as follows: This equivalent method is based on linear damage theory. If the stress amplitude S i corresponds to the number of cycles n i when, the equivalent stress amplitude S c that produces the same damage is:

[0083]

[0084] Where: 1 / b is the slope of the designed fatigue curve of the test piece material on the double logarithmic coordinate, and i is the number of points in the amplitude statistical program.

[0085] The result obtained by applying this method is that an equivalent test duration of 0.43 hours can be equivalent to the fluid-induced vibration load suffered by the hanging basket connection parts in 60 years. Based on the original fluid-induced vibration test data, according to the same equivalent principle, an equivalent test duration of 0.15 hours can be equivalent to the fluid-induced vibration load suffered by the hanging basket connection parts in 60 years. The method for obtaining the equivalent test duration of the fluid-induced vibration acceleration test load of the present disclosure has a longer equivalent test duration and is more conservative, and can be used for engineering applications.

[0086] Embodiment 2

[0087] The purpose of this embodiment is to provide a test duration acquisition system for the equivalent vibration test of loose parts, including:

[0088] Fluid calculation module establishment module: Establish a fluid calculation model of the loose parts, and obtain fluid physical parameters according to the established fluid calculation model;

[0089] Calculation module: Calculate the fluid-induced vibration load suffered by the loose parts based on the fluid-induced vibration theory according to the obtained physical parameters;

[0090] First analysis module: Based on the finite element model of the loose parts, obtain the acceleration power spectral density function of the response of the loose parts under the fluid-induced vibration load by using modal analysis and random vibration analysis methods;

[0091] Second analysis module: Perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data;

[0092] Test module: Obtain the equivalent test time based on the linear damage theory according to the acceleration amplitude statistical data, and perform an equivalent test on the loose parts.

[0093] Embodiment 3

[0094] The purpose of this embodiment is to provide a computing device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the above method are implemented.

[0095] Embodiment 4

[0096] The purpose of this embodiment is to provide a computer-readable storage medium.

[0097] A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the above method are executed.

[0098] In the devices of the second, third, and fourth embodiments above, the steps involved correspond to those of the first method embodiment. For the specific implementation, reference may be made to the relevant description part of the first embodiment. The term "computer-readable storage medium" should be understood to include a single medium or multiple media containing one or more instruction sets; it should also be understood to include any medium that can store, encode, or carry an instruction set for execution by a processor and cause the processor to execute any method in the present invention.

[0099] Those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computer device. Optionally, they can be implemented by program codes executable by a computing device. Thus, they can be stored in a storage device for execution by the computing device, or they can be separately fabricated into individual integrated circuit modules, or multiple of them can be fabricated into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0100] Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present invention.

Claims

1. A method for obtaining the test duration of the equivalent vibration test of a loose part, characterized in that, it includes: Establish a fluid calculation model of the loose part, and obtain fluid physical parameters according to the established fluid calculation model; Based on the obtained physical parameters, calculate the fluid-induced vibration load suffered by the loose part according to the fluid-induced vibration theory; Based on the finite element model of the loose part, obtain the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load by using modal analysis and random vibration analysis; Perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data; Based on the acceleration amplitude statistical data, obtain the equivalent test time according to the linear damage theory, and conduct an equivalent test on the loose part.

2. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 1, characterized in that, the fluid physical parameters include flow velocity, density and void fraction.

3. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 1, characterized in that, Calculating the fluid-induced vibration load suffered by the loose part based on the obtained physical parameters according to the fluid-induced vibration theory specifically includes: according to the obtained physical parameters of the fluid, using the classical empirical formula method in the fluid-induced vibration theory to calculate the power spectral density curve of the turbulent pressure pulsation on the surface of the loose part, and taking the calculated power spectral density curve of the turbulent pressure pulsation on the surface of the loose part as the fluid-induced vibration load suffered by the loose part.

4. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 1, characterized in that, Based on the finite element model of the loose part, obtaining the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load by using modal analysis and random vibration analysis specifically is: Establish a finite element model of the loose part according to the physical parameters of the loose part; Conduct modal analysis on the finite element model of the loose part; Apply the fluid-induced vibration load to the finite element model of the loose part, and perform finite element calculation by using random vibration analysis in spectral analysis to obtain the acceleration power spectral density function at the connection position of the loose part.

5. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 4, characterized in that, In the modal analysis of the finite element model of the loose part, the highest first-order modal frequency is greater than the highest frequency of the power spectral density function corresponding to the fluid-induced vibration load.

6. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 1, characterized in that, Performing time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data specifically is: Solve the Fourier spectrum corresponding to the acceleration power spectral density function; Superimpose the solved Fourier spectrum with random phases and then perform inverse Fourier transform to obtain the acceleration time history; According to the acceleration time history, obtain the acceleration statistical data by using the mean crossing peak counting method.

7. The method for obtaining the test duration of the equivalent vibration test of a loose part according to claim 6, characterized in that, Acceleration statistical data is obtained through the mean crossing peak counting method, specifically: the number and magnitude of wave peaks and wave valleys in the time history curve are counted to obtain the acceleration amplitude statistical data.

8. A test duration acquisition system for equivalent vibration test of loose parts, characterized in that, it includes: Fluid calculation module establishment module: establish a fluid calculation model of the loose part, and obtain fluid physical parameters according to the established fluid calculation model; Calculation module: calculate the fluid-induced vibration load received by the loose part based on the obtained physical parameters according to the fluid-induced vibration theory; First analysis module: based on the finite element model of the loose part, obtain the acceleration power spectral density function of the response of the loose part under the fluid-induced vibration load by means of modal analysis and random vibration analysis; Second analysis module: perform time history analysis on the obtained acceleration power spectral density function to obtain acceleration amplitude statistical data; Test module: obtain the equivalent test time based on the linear damage theory according to the acceleration amplitude statistical data, and perform an equivalent test on the loose part.

9. A computer device, characterized in that, it includes: A processor, a memory and a bus, the memory stores machine-readable instructions executable by the processor. When the computer device runs, the processor communicates with the memory through the bus. When the machine-readable instructions are executed by the processor, it executes a method for obtaining the test duration of an equivalent vibration test of a loose part according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, a computer program is stored on the computer-readable storage medium, and when the computer program is run by a processor, it executes a method for obtaining the test duration of an equivalent vibration test of a loose part according to any one of claims 1 to 7.

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