Method for predicting vibration environment of aeronautical equipment structure

Abstract

The application provides a vibration environment prediction method for aviation equipment structure, relates to the field of environmental engineering, and comprises the following steps: S1, measuring vibration responses of known vibration points; S2, determining demarcation points of a path L1; S3, partitioning a region of a structure plane; S4, solving frequency response functions from the known vibration points to designated to-be-measured points in each partition; S5, solving vibration responses of the designated to-be-measured points in each partition; and S6, sequentially solving vibration responses of multiple designated to-be-measured points in each partition. The point partitioning method provided by the application adopts the similarity of the power spectrum density curves of the measured responses as a partitioning index, compared with the traditional partitioning method based on the physical structure, is more scientific and reasonable, and is beneficial to realizing accurate prediction of the vibration environment.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering, and more specifically to a method for predicting the vibration environment of aerospace equipment structures. Background Technology

[0002] Structural vibration is a common mechanical phenomenon. Harmful vibrations can accelerate wear, cause deformation or fracture, and seriously affect the normal use of products. Therefore, accurate prediction of structural vibration response is essential.

[0003] In engineering, vibration response prediction typically employs simulation and experimental methods. Simulation offers the advantage of capturing the overall structural response; however, it demands significant computing power for large or complex structures, resulting in substantial time and labor costs. Experimental methods, on the other hand, provide higher accuracy than simulation. However, they impose strict requirements on the number and placement of sensors, making it difficult to obtain the overall structural response or responses at specific locations (such as abrupt changes in shape or inaccessible areas). Therefore, it is necessary to develop a vibration response prediction method that combines the advantages of both approaches.

[0004] For simulation and experimental methods, vibration prediction essentially involves multiplying the vibration response at known points by the frequency response function to calculate the vibration response at unknown points. The frequency response function is the mathematical representation of the vibration of a physical structure. Since the vibration characteristics differ across different regions of the structure, the frequency response functions at different measurement points also differ. To improve computational efficiency, engineering practices typically divide all measurement points into a finite number of regions, where the frequency response function characteristics of measurement points within each region are most similar, and the differences between measurement points in different regions are greatest. However, current structural vibration zoning methods are relatively crude, dividing the structure solely based on its physical characteristics without considering the similarity of the frequency response function characteristics of the measurement points. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for predicting the vibration environment of aerospace equipment structures. This method first divides the planar region of the structure into partitions based on measured data. Then, it combines finite element simulation to construct frequency response functions from known vibration points to each specified test point within each partition. The constructed frequency response functions are then used to solve for the vibration response of each specified test point under different excitations. This combination of measured partitioning and simulation calculations overcomes the large workload of traditional simulation calculations while ensuring the accuracy of calculating the vibration response of the specified test points under different excitations.

[0006] Specifically, the present invention provides a method for predicting the vibration environment of aerospace equipment structures, which includes the following steps:

[0007] S1. Measure the vibration response of a known vibration point: Define the plane of a certain aerospace equipment structure as region A, where point P is a known vibration point on the structure. When the structure is subjected to external excitation T, measure the vibration response V(P) of point P.

[0008] S2. Determine the boundary point of path L1: Starting from point P, measure the vibration response of a point on path L1 sequentially within region A at a certain step size, and calculate the similarity of the power spectral density curves of the vibration responses of each measurement point and point P. Determine a reference measurement point P1 on path L1 as the boundary point of path L1.

[0009] The power spectral density curves of the vibration response V(P1) at point P1 and the vibration response V(P) at point P are within the similarity threshold, and the next point P1 is... 1’ Vibration response V(P) 1’ The similarity between the power spectral density curve of the vibration response V(P) at point P and that at point P is outside the similarity threshold;

[0010] S3. Divide the structural plane into regions: First, starting from point P, sequentially set different paths L2 to L3 within region A. N Repeat step S2 to obtain paths L2 to L1 in sequence. N The corresponding dividing points P2~P N Then connect the boundary points P1 to P2 of multiple paths in sequence. N This forms a closed area, which serves as the first partition of region A.

[0011] Then, in other areas outside the first partition, repeat steps S1 to S3 to divide area A into multiple independent partitions, thus completing the partitioning of area A of the structural plane.

[0012] S4. Construct the frequency response function from the known vibration point to the specified test point within each partition: For the specified test point M within any partition, calculate the power spectral density (PSD) of the vibration response of the specified test point M using finite element simulation under arbitrary excitation. V(M) And solve the frequency response function H(P, M) from the known vibration point P to the specified test point M. The calculation formula is as follows:

[0013] H(P, M) = PSD V(M) / PSD V(P)

[0014] Where H(P, M) is the frequency response function from the known vibration point P to the specified test point M, and PSD V(P) Given the power spectral density (PSD) of the vibration response at point P,... V(M) The power spectral density of the vibration response at the specified test point M;

[0015] S5. Solve for the vibration response of a specified test point within each partition: Solve for the vibration response V(M) of a specified test point M under different excitations. The calculation formula is as follows:

[0016] V(M) = V(P) * H(P, M)

[0017] Wherein, V(M) is the vibration response of a specified test point M under a certain excitation, and V(P) is the vibration response of a known vibration point P under a certain excitation;

[0018] S6. Solve the vibration response of multiple specified test points in each partition in turn: Repeat steps S4-S5 to calculate the vibration response of multiple specified test points in each partition in turn.

[0019] Preferably, the power spectral density curves of all measurement points in step S2 have the same frequency bandwidth.

[0020] Preferably, the power spectral density curve is the limiting mean square value of vibration acceleration within a unit frequency bandwidth.

[0021] Preferably, the similarity being within the similarity threshold means that the ratio of the power spectral densities of the two power spectral density curves at the same frequency point is within a predetermined similarity threshold.

[0022] Preferably, the frequency response function refers to the ratio of the system vibration response to the excitation when the structure is a steady linear system.

[0023] Preferably, the power spectral density of the vibration response at the known vibration point P in step S4 is obtained through finite element simulation or measurement.

[0024] Preferably, step S6 specifically includes the following sub-steps:

[0025] S61. Solve for the power spectral density of the vibration response at the known vibration point in each partition.

[0026] S62. Within a partition, construct the frequency response function from the known vibration point to each specified test point;

[0027] S63. Solve the vibration response of each specified test point under different excitations within a partition;

[0028] S64. Repeat steps S61-S63 in each partition.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The vibration environment prediction method for the aerospace equipment structure of the present invention first divides the planar area of ​​the structure into partitions based on measured data. Then, it combines finite element simulation to construct the frequency response function from the known vibration point to each specified test point in each partition. The vibration response under different excitations at each specified test point is solved by the constructed frequency response function. Combining measured partitions with simulation calculations overcomes the large workload of all simulation calculations and ensures the accuracy of calculating the vibration response under different excitations at the specified test points.

[0031] (2) The measurement point partitioning method proposed in this invention uses the similarity of the power spectral density curve of the measured response as the partitioning index, which is more scientific and reasonable than the traditional partitioning method based on physical structure, and is conducive to the accurate prediction of vibration environment.

[0032] (3) The vibration hybrid prediction method proposed in this invention is based on the measured data of structural response and divides the data into partitions. It combines the advantages of finite element simulation and frequency response function analysis, resulting in high computational efficiency and more accurate prediction results. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the vibration environment prediction method for aerospace equipment structures according to the present invention.

[0034] Figure 2 This is a schematic diagram of the structural planar partitioning of an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of known vibration points and reference measurement points in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the vibration zone centered on point P in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the power spectral density at point P1 in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the vibration power spectral density at point M calculated in the embodiment of the present invention;

[0039] Figure 7 This is a schematic diagram of the transfer function between points M and P in this invention;

[0040] Figure 8 This is a schematic diagram of the measured vibration power spectral density at point P and the predicted vibration power spectral density at point M in this invention. Detailed Implementation

[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0042] This invention provides a method for predicting the vibration environment of aerospace equipment structures, such as... Figure 1 As shown, it includes the following steps:

[0043] S1. Measuring the vibration response at a known vibration point: Define the plane of a certain aerospace equipment structure as region A, where point P is a known vibration point on the structure. When the structure is subjected to an external excitation T, measure the vibration response V(P) at point P. The vibration response V(P) at point P is measured by a sensor. After obtaining the vibration response, extract the response with a certain frequency bandwidth and calculate the power spectral density.

[0044] S2. Determine the boundary point of path L1: Starting from point P, measure the vibration response of a point along path L1 within region A at a certain step size, and calculate the similarity of the power spectral density curves of the vibration responses of each measurement point and point P. In practical applications, the step size can be set according to the area of ​​region A. Determine a reference measurement point P1 on path L1 as the boundary point of path L1, where the similarity of the power spectral density curves of the vibration response V(P1) at point P1 and the vibration response V(P) at point P is within a similarity threshold, and the next point P1 is... 1’ Vibration response V(P) 1’ The similarity between the power spectral density curve of the vibration response V(P) at point P and that of point P is outside the similarity threshold.

[0045] Similarity within a certain threshold means that the ratio of the power spectral densities of the two power spectral density curves at the same frequency point is within a predetermined similarity threshold. A reference measurement point P1 can always be found on the path that meets this requirement.

[0046] In step S2, the power spectral density curves at all measurement points have the same frequency bandwidth. The power spectral density curve represents the limiting mean square value of vibration acceleration per unit frequency bandwidth.

[0047] S3. Divide the structural plane into regions: First, starting from point P, sequentially set different paths L2 to L3 within region A. N Repeat step S2 to obtain paths L2 to L1 in sequence. N The corresponding dividing points P2~P N Then connect the boundary points P1 to P2 of multiple paths in sequence. N This forms a closed area, which serves as the first partition of region A.

[0048] Then, in the other areas outside the first partition, repeat steps S1 to S3 to divide area A into multiple independent partitions, thus completing the partitioning of area A of the structural plane.

[0049] The above-mentioned measurement point zoning method uses the similarity of the power spectral density curves of the measured response as the zoning index. Compared with the traditional zoning method based on physical structure, it is more scientific and reasonable, and is conducive to the accurate prediction of vibration environment.

[0050] S4. Construct the frequency response function from the known vibration point to the specified test point within each partition: For the specified test point M within any partition, calculate the power spectral density (PSD) of the vibration response of the specified test point M using finite element simulation under any excitation. V(M) And solve the frequency response function H(P, M) from the known vibration point P to the specified test point M. The calculation formula is as follows:

[0051] H(P, M) = PSD V(M) / PSD V(P)

[0052] Where H(P, M) is the frequency response function from the known vibration point P to the specified test point M, and PSD V(P) Given the power spectral density (PSD) of the vibration response at point P,... V(M) The power spectral density of the vibration response at a specified test point M is given. The power spectral density of the vibration response at a known vibration point P is obtained through finite element simulation or measurement. The power spectral density of the vibration response at the specified test point M is obtained through simulation calculation. By solving the frequency response function from the known vibration point P to the specified test point M under any excitation, the vibration response of the specified test point M under any excitation can be directly solved without using the finite element method for each excitation, saving a significant amount of computation. Furthermore, since it is based on measured partitions, the accuracy of the calculated vibration response can be guaranteed.

[0053] S5. Solve for the vibration response of a specified test point within each partition: Solve for the vibration response V(M) of a specified test point M under different excitations. The calculation formula is as follows:

[0054] V(M) = V(P) * H(P, M)

[0055] Where V(M) is the vibration response of a specified test point M under a certain excitation, and V(P) is the vibration response of a known vibration point P under a certain excitation. Based on the frequency response function obtained in the previous step, this formula can be used to directly solve for the vibration response of a specified test point M under any excitation.

[0056] S6. Sequentially calculate the vibration response of multiple specified test points within each partition: Repeat steps S4-S5 to sequentially calculate the vibration response of multiple specified test points within each partition, thereby obtaining the complete vibration distribution of the structure.

[0057] Step S6 specifically includes the following sub-steps:

[0058] S61. Solve for the power spectral density of the vibration response at the known vibration point P in each partition; use simulation analysis or experimental methods to obtain the power spectral density of the vibration response at the known vibration point P in each partition.

[0059] S62. Construct the frequency response function from the known vibration point to each specified test point within a partition; for any specified test point within each partition, construct the frequency response function from the known vibration point to each specified test point under any excitation according to the above frequency response function construction formula.

[0060] S63. Solve the vibration response of each specified test point under different excitations within a partition; under different excitations, for any specified test point within each partition, use the constructed frequency response function from the known vibration point to each specified test point to solve the vibration response of each specified test point under different excitations.

[0061] S64. Repeat steps S61-S63 in each partition to solve the vibration response of any fixed test point on the structure under different excitations, thereby obtaining the complete vibration distribution of the structure.

[0062] The vibration environment prediction method for aerospace equipment structures of the present invention first divides the planar region of the structure into partitions based on measured data. Then, it combines finite element simulation to construct the frequency response function from the known vibration point to each specified test point in each partition. The vibration response of each specified test point under different excitations is solved by the constructed frequency response function. Combining measured partitioning with simulation calculation not only overcomes the large workload of full simulation calculation, but also ensures the accuracy of calculating the vibration response of the specified test point under different excitations. Specific Implementation

[0064] This invention provides a method for predicting the vibration environment of an aircraft's equipment installation platform, such as... Figure 2-7 As shown, it includes the following steps:

[0065] S1. The structural planar partitioning of the equipment installation platform for a certain type of aircraft is as follows: Figure 2 As shown. Figure 3 As shown, point P is a known vibration point on the platform. When the platform is subjected to external vibration excitation T, a vibration sensor is used to measure the vibration response V(P) at point P, and the power spectral density PSD of V(P) from 15Hz to 1000Hz is calculated. V(P) .

[0066] S2. Starting from point P, along path L1 within the planar region A where the platform is located, measure the vibration response of each corresponding point on path L1 sequentially with a certain step size, and calculate the power spectral density from 15Hz to 1000Hz. Set the similarity threshold to ±3dB, and calculate the similarity between the power spectral density curves of the vibration responses of multiple measurement points and point P.

[0067] Until a point P1 is found in the plane such that point P1 satisfies:

[0068] The similarity between the power spectral density curves of the vibration response V(P(1)) at point P1 and the vibration response V(P) at point P is within the similarity threshold of ±3dB.

[0069] The next point P1 is P 1’ Vibration response V(P) 1’ The similarity between the power spectral density curve of the vibration response V(P) at point P and that at point P is outside the similarity threshold of ±3dB.

[0070] S3. Starting from point P, sequentially set different paths L2 to L3 in region A. N Repeat step S2 to obtain paths L2 to L1 in sequence. N The corresponding dividing points P2~P N Connect P1 to P2 in sequence. N This forms a closed region, creating the first vibration zone centered on point P. This step is repeated to find multiple zones centered on known vibration points, thus dividing region A into multiple zones. Figure 4 This is a schematic diagram of the vibration zone centered on point P in an embodiment of the present invention; Figure 5 This is a schematic diagram of the power spectral density at point P1 in an embodiment of the present invention.

[0071] S4. For a specified point M within the first partition, use finite element simulation to calculate the power spectral density (PSD) of the vibration response at point M. V(M) The frequency bandwidth is 15Hz to 2000Hz, such as Figure 6 As shown.

[0072] Calculate the frequency response function H(P, M) from point P to point M. That is:

[0073] H(P, M) = PSD V(M) / PSD V(P) The calculation results are attached. Figure 7 As shown.

[0074] S5. When the platform is subjected to arbitrary external vibration excitation Y, measure the vibration response at point P and calculate the power spectral density from 15Hz to 2000Hz, then multiply by... Figure 7The frequency response function H(P, M) from point P to point M can be used to predict the power spectral density of the response at point M under arbitrary external vibration excitation Y, as shown in the attached figure. Figure 8 As shown.

[0075] S6. Based on the fact that the structure is a steady system, the frequency response function H(P, M) from point P to the specified point within the first partition does not change with the external input excitation T. Therefore, for any external input excitation T, the vibration response V(M) at the specified point M can be calculated by measuring the vibration response V(P) at point P and multiplying it by the frequency response function H(P, M). Similarly, for any test point X within the first partition, the vibration response can be predicted according to steps S5 and S6. Repeating the above steps for the remaining partitions will yield the vibration response of any test point within any partition. The specific steps are as follows:

[0076] S61. Solve for the power spectral density of the vibration response at the known vibration point P in each partition; use simulation analysis or experimental methods to obtain the power spectral density of the vibration response at the known vibration point P in each partition.

[0077] S62. Construct the frequency response function from the known vibration point to each specified test point within a partition; for any specified test point within each partition, construct the frequency response function from the known vibration point to each specified test point under any excitation according to the above frequency response function construction formula.

[0078] S63. Solve the vibration response of each specified test point under different excitations within a partition; under different excitations, for any specified test point within each partition, use the constructed frequency response function from the known vibration point to each specified test point to solve the vibration response of each specified test point under different excitations.

[0079] S64. Repeat steps S61-S63 in each partition to solve the vibration response of any fixed test point on the structure under different excitations, thereby obtaining the complete vibration distribution of the structure.

[0080] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for predicting the vibration environment of aircraft equipment structures, characterized in that: It includes the following steps: S1. Measure the vibration response of a known vibration point: Define the plane of a certain aviation equipment structure as region A, where point P is a known vibration point on the structure. When the aviation equipment structure is subjected to external excitation T, measure the vibration response V(P) of point P. S2. Determine the boundary point of path L1: Starting from point P, measure the vibration response of a point on path L1 sequentially within region A at a certain step size, and calculate the similarity of the power spectral density curves of the vibration responses of each measurement point and point P. Determine a reference measurement point P1 on path L1 as the boundary point of path L1. The power spectral density curves of the vibration response V(P1) at point P1 and the vibration response V(P) at point P are within the similarity threshold, and the next point P1 is... 1’ Vibration response V(P) 1’ The similarity between the power spectral density curve of the vibration response V(P) at point P and that at point P is outside the similarity threshold; S3. Divide the structural plane into regions: First, starting from point P, sequentially set different paths L2~L3 within region A. N Paths L2 to L are obtained sequentially. N The corresponding dividing points P2~P N Then connect the boundary points P1~P of multiple paths in sequence. N This forms a closed area, which serves as the first partition of region A. Then, in other areas outside the first partition, repeat steps S1 to S3 to divide area A into multiple independent partitions, thus completing the partitioning of area A of the structural plane. S4. Construct the frequency response function from the known vibration point to the specified test point within each partition: For the specified test point M within any partition, calculate the power spectral density (PSD) of the vibration response of the specified test point M using finite element simulation under arbitrary excitation. V(M) And solve the frequency response function H(P, M) from the known vibration point P to the specified test point M. The calculation formula is as follows: H(P,M)= PSD V(M) / PSD V(P) Where H(P, M) is the frequency response function from the known vibration point P to the specified test point M, and PSD V(P) Given the power spectral density (PSD) of the vibration response at point P,... V(M) The power spectral density of the vibration response at the specified test point M; S5. Solve for the vibration response of a specified test point within each partition: Solve for the vibration response V(M) of a specified test point M under different excitations. The calculation formula is as follows: V(M) = V(P) * H(P, M) Wherein, V(M) is the vibration response of a specified test point M under a certain excitation, and V(P) is the vibration response of a known vibration point P under a certain excitation; S6. Solve the vibration response of multiple specified test points in each partition in turn: Repeat steps S4-S5 to calculate the vibration response of multiple specified test points in each partition in turn.

2. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: In step S2, the power spectral density curves of all measurement points have the same frequency bandwidth.

3. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: The power spectral density curve is the limiting mean square value of vibration acceleration within a unit frequency bandwidth.

4. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: Similarity within the similarity threshold means that the ratio of the power spectral density of the two power spectral density curves at the same frequency point is within the predetermined similarity threshold.

5. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: The frequency response function refers to the ratio of the system's vibration response to the excitation when the structure is a steady linear system.

6. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: In step S4, the power spectral density of the vibration response at the known vibration point P is obtained through finite element simulation or measurement.

7. The vibration environment prediction method for aerospace equipment structures according to claim 1, characterized in that: Step S6 specifically includes the following sub-steps: S61. Solve for the power spectral density of the vibration response at a known vibration point within a given partition; S62. Within a partition, construct the frequency response function from the known vibration point to each specified test point; S63. Solve the vibration response of each specified test point under different excitations within a partition; S64. Repeat steps S61-S63 in each partition.

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