A method for quantitatively judging the operation stability of a vibration mechanism in a dynamic derivative test

Abstract

The present invention discloses a method for quantitatively judging the running stability of a vibration mechanism in a dynamic derivative test, which relates to the technical field of fault prediction. The purpose is to solve the problem that there is no unified evaluation index for whether a test mechanism fails in the existing dynamic derivative test of a high-speed wind tunnel. The present invention adopts the idea of "normalization". First, the angular displacement voltage value data is normalized to unify the data scales of the angular displacement voltage values under different mechanisms or different working conditions. Then, the sum of the squares of the residuals of a single period between it and the standard sine curve is calculated. Finally, by evaluating whether the sum of the squares of the residuals of a single period exceeds the judgment index and whether the angular displacement amplitude exceeds the tolerance, it is judged whether the mechanism fails. The present invention provides important support for improving equipment performance, extending service life and ensuring safety in the fields of aerospace.

Description

Technical Field

[0001] The present invention relates to the technical field of fault prediction, and particularly relates to a method for quantitatively judging the operation stability of a vibration mechanism in a dynamic derivative test. Background Art

[0002] The forced vibration dynamic derivative test technology of a high-speed wind tunnel relies on a dynamic derivative vibration mechanism to make a model perform a standard sinusoidal simple harmonic motion, and obtains dynamic derivative data by measuring the moment and angle history of the model under the conditions of set frequency and amplitude. The sinusoidality of the vibration of the dynamic derivative mechanism is the key to accurately measuring the dynamic derivative test, which determines the accuracy of the dynamic derivative test results.

[0003] Currently, the evaluation method for the vibration stability of the dynamic derivative test mechanism is to conduct a commissioning test of the test mechanism on the ground. Its main purpose is to adjust the test mechanism to the optimal state before the in-cave test. The main commissioning contents include adjusting the model counterweight, determining the optimal test frequency, optimizing the mechanism clearance, etc. The usual measurement index is that the mechanical damping value reaches the minimum and stable state. However, restricted by conditions such as different models and different mechanisms, there is no specific quantifiable evaluation index for the mechanical damping under the air vibration condition.

[0004] In addition, during the high-speed wind tunnel large angle of attack dynamic derivative test, the reciprocating transmission components of the dynamic derivative test mechanism will inevitably wear and even deform under the high-load environment, resulting in an increasing movement clearance of the mechanism, leading to a non-sinusoidal trend in the vibration angular displacement, seriously affecting the repeatability accuracy of the test results. Therefore, it is usually necessary to manually monitor and analyze the data based on experience to judge whether the worn parts need to be replaced. However, there are omissions or inconsistent judgment experiences / standards in the analysis process of the test personnel, affecting the reliability of the data. Even due to untimely monitoring, it may lead to batch scrapping of test runs. Summary of the Invention

[0005] To solve the problem that there is no unified evaluation index for whether the test mechanism fails in the existing high-speed wind tunnel dynamic derivative test, the present invention provides a method for quantitatively judging the operation stability of a vibration mechanism in a dynamic derivative test, including the following steps:

[0006] S1. Perform the first fitting on the original angular displacement voltage value signal, and then obtain the average voltage amplitude through parameter identification;

[0007] S2. Judge whether the angular displacement amplitude exceeds the tolerance. If it exceeds 5% of the design value, it is necessary to check whether the dynamic derivative test vibration mechanism is overloaded;

[0008] S3. Perform normalization processing on the original angular displacement voltage value signal to obtain the normalized angular displacement voltage value signal;

[0009] S4. Perform a second fitting on the normalized angular displacement voltage value signal to obtain a quadratic fitting standard sine curve;

[0010] S5. Obtain the sum of the squares of the residuals between the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve under a single vibration period;

[0011] S6. Determine whether the sum of the squares of the residuals under a single period is greater than the evaluation index. If it is greater, it is necessary to check whether there is an abnormality in the dynamic derivative vibration mechanism.

[0012] Further, the first fitting of the original angular displacement voltage value signal is passed through:

[0013] ;

[0014] Realize, where is the original angular displacement voltage value signal, is the average voltage amplitude to be identified, is the nominal vibration frequency, is the acquisition time series, is the zero-crossing moment of the first period, is the DC component.

[0015] Further, in S2, the angular displacement amplitude is obtained through:

[0016] ;

[0017] Obtain, where is the angular displacement amplitude, is the angular displacement calibration coefficient.

[0018] Further, in S3, the normalized angular displacement voltage value signal is obtained through:

[0019] ;

[0020] Obtain, where is the normalized angular displacement voltage value signal.

[0021] Further, in S4, the quadratic fitting standard sine curve is realized through:

[0022] ;

[0023] Realize, where is the quadratic fitting standard sine curve, is the average voltage amplitude of the normalized angular element voltage signal, is the zero-crossing moment of the first period of the normalized angular element voltage signal, is the DC component of the normalized angular element voltage signal.

[0024] Further, in S5, within a single vibration period, the sum of the squares of the residuals between the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve is obtained through:

[0025] ;

[0026] wherein, is the normalized angular displacement voltage value signal of the i th cycle, is the quadratic fitting standard sine curve of the i th cycle, is the sum of the squares of the residuals within a single cycle, and N is the cycle.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. A unified evaluation criterion can be established among different mechanisms, different-angle balances, different loads, different vibration frequencies, different sampling times, and other working conditions;

[0029] 2. It is convenient and fast, reduces the influence of human experience, can detect faults in a timely manner, ensures the reliability of data, and avoids the generation of batch scrapped train trips;

[0030] 3. It is beneficial to discover problems in the first time, thereby reducing the burden on pneumatic analysis personnel, improving the test efficiency, and ensuring the data quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flowchart for judging the running stability of the mechanism;

[0032] Figure 2 is a curve of the angular displacement voltage value of the mechanism with better sinusoidality during operation;

[0033] Figure 3 is a curve of the angular displacement voltage value of the mechanism with poorer sinusoidality during operation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the technical solutions and advantages in the embodiments of the present invention clearer, the following further details the exemplary embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0035] Embodiment 1, in combination with Figure 1 This embodiment is described. The present invention provides a method for quantitatively judging the running stability of a vibration mechanism in a dynamic derivative test, including the following steps:

[0036] S1. Perform the first fitting on the original angular displacement voltage value signal, and then obtain the average voltage amplitude through parameter identification.

[0037] S2. Determine whether the angular displacement amplitude exceeds the tolerance. If it exceeds 5% of the design value, it is necessary to check whether the vibration mechanism of the dynamic derivative test is overloaded.

[0038] S3. Normalize the original angular displacement voltage value signal to obtain the normalized angular displacement voltage value signal.

[0039] S4. Perform the second fitting on the normalized angular displacement voltage value signal to obtain the second - order fitting standard sine curve.

[0040] S5. Obtain the sum of the squares of the residuals between the normalized angular displacement voltage value signal and the second - order fitting standard sine curve under a single vibration period.

[0041] S6. Determine whether the sum of the squares of the residuals under a single period is greater than the evaluation index. If it is greater, it is necessary to check whether there is an abnormality in the dynamic derivative vibration mechanism.

[0042] Specifically, the evaluation index is the optimal free - vibration quantity value of the vibration mechanism in the current test or the empirical value obtained from multiple statistics. The present invention monitors the angular vibration waveform to evaluate the operation and debugging of the test mechanism, the replacement requirements of easily worn parts, the rationality of repeated train trips, and the selection of the optimal test frequency, so as to improve the judgment accuracy and efficiency. The present invention adopts the "normalization" idea. After completing the first fitting of the original angular displacement voltage value signal and obtaining the average voltage amplitude, if the angular displacement amplitude does not exceed 5% of the design value (otherwise, it is necessary to check whether the vibration mechanism is overloaded), first normalize the original angular displacement voltage value data to unify the data scale of the angular displacement voltage value under different mechanisms or different working conditions; then, generate the second - order fitting standard sine curve for the normalized angular displacement voltage value signal through the second - order fitting algorithm, and calculate the sum of the squares of the residuals between the normalized angular displacement voltage value signal and the second - order fitting standard sine curve within a single vibration period. Finally, determine whether the mechanism fails by evaluating whether the sum of the squares of the residuals under a single period exceeds the judgment index.

[0043] The first fitting of the original angular displacement voltage value signal is achieved through:

[0044] ;

[0045] wherein, is the original angular displacement voltage value signal, is the average voltage amplitude to be identified, is the nominal vibration frequency, is the acquisition time series, is the zero-crossing moment of the first cycle, is the DC component.

[0046] In S2, the angular displacement amplitude is obtained through:

[0047] ;

[0048] where, is the angular displacement amplitude, is the angular displacement calibration coefficient.

[0049] In S3, the normalized angular displacement voltage value signal is obtained through:

[0050] ;

[0051] where, is the normalized angular displacement voltage value signal.

[0052] In S4, the quadratic fitting standard sine curve is achieved through:

[0053] ;

[0054] where, is the quadratic fitting standard sine curve, is the average voltage amplitude of the normalized angular element voltage signal, is the zero-crossing moment of the first cycle of the normalized angular element voltage signal, is the DC component of the normalized angular element voltage signal.

[0055] In S5, under a single vibration cycle, the sum of squared residuals between the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve is obtained through:

[0056] ;

[0057] where, is the normalized angular displacement voltage value signal of the i th cycle, is the quadratic fitting standard sine curve of the i th cycle, is the sum of squared residuals under a single cycle, N is the cycle.

[0058] Specifically, the result example is shown in Appendix Figure 2 and Appendix Figure 3 as shown, Figure 2 the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve are in good agreement ( SSE is small), indicating that the mechanism runs stably and has low noise interference;Figure 3 There are significant distortions in the signal of ( SSE relatively large), indicating that the mechanism has non-sinusoidal vibration due to wear or increased clearance, and the fault needs to be investigated.

Claims

1. A method for quantitatively determining the operating stability of a vibration mechanism in a dynamic derivative test, characterized in that: The following steps are involved: S1. Perform the first fitting on the original angular displacement voltage value signal, and then obtain the average voltage amplitude through parameter identification; S2. Determine whether the angular displacement amplitude exceeds the tolerance. If it exceeds the design value by 5%, it is necessary to check whether the dynamic derivative test vibration mechanism is overloaded; S3. normalizing the original angular displacement voltage value signal to obtain a normalized angular displacement voltage value signal; S4. Perform a second fitting on the normalized angular displacement voltage value signal to obtain a quadratic fitting standard sine curve; S5. Obtain the residual sum of squares between the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve under a single vibration cycle; S6. Determine whether the residual sum of squares in a single cycle is greater than the evaluation index. If so, check whether the dynamic derivative vibration mechanism has any abnormality.

2. A method for quantitatively judging the running stability of a vibration mechanism by a dynamic derivative test according to claim 1, characterized in that: The first fitting pass of the original angular displacement voltage value signal is: ； To achieve, is the original angular displacement voltage value signal, is the average voltage amplitude to be identified, is the nominal vibration frequency, To collect time series, is the first cycle zero-crossing moment, is the DC component.

3. The method for quantitatively judging the running stability of a vibration mechanism by a dynamic derivative test according to claim 1, characterized in that: In S2, the angular displacement amplitude is given by: ； Obtain, among which, is the angular displacement amplitude, is the angular displacement calibration coefficient.

4. The method for quantitatively judging the running stability of a vibration mechanism by a dynamic derivative test according to claim 1, characterized in that: In S3, the normalized angular displacement voltage value signal is obtained by: ； Obtain, among which, is the normalized angular displacement voltage value signal.

5. The method for quantitatively judging the running stability of a vibration mechanism by a dynamic derivative test according to claim 1, characterized in that: In S4, the quadratic fit to the standard sine curve is done by: ； To achieve, is the quadratic fit to the standard sine curve, is the average voltage amplitude of the normalized angle element voltage signal, is the first cycle zero-crossing moment of the normalized angle element voltage signal, is the DC component of the normalized angle element voltage signal.

6. The method for quantitatively judging the running stability of a vibration mechanism by a dynamic derivative test according to claim 1, characterized in that: In S5, in a single vibration cycle, the residual sum of squares between the normalized angular displacement voltage value signal and the quadratic fitting standard sine curve is calculated by: ； Obtain, among which, For the i The angular displacement voltage value signal after normalization of the cycle, For the i The quadratic fit of the standard sine curve is is the residual sum of squares in a single period, N For cycle.

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