Method for testing vibration characteristics of inflatable wing

Abstract

The invention provides a method for testing vibration characteristics of an inflatable wing. The method comprises the following steps: S1, spraying speckles on a wing surface of a to-be-tested inflatable wing; s2, fixing the inflatable wing to be tested on a vibration table, and adjusting the high-speed camera until the visual angle covers the wing surface; s3, starting the acceleration test device and the DIC test device, and configuring a first test parameter for the vibration table to perform device calibration; s4, configuring a second test parameter for the fine adjustment valve and the vibration table, and carrying out a vibration frequency sweeping test to obtain first test data; s5, closing the DIC test device, configuring third test parameters for the fine adjustment valve and the vibration table, carrying out random vibration test, and recording second test data; and S6, performing signal data analysis and atlas transformation on the first test data and the second test data to obtain inherent frequencies, vibration modes and damping ratios of the first several orders of the inflatable wing to be tested. The beneficial effects are that the method can comprehensively and accurately test the vibration characteristics of the inflatable wing, and improves the flight performance and stability of an aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of wing performance testing methods, and more particularly, to a method for testing the vibration characteristics of an inflatable wing. Background Art

[0002] Inflatable wings have shown broad application prospects in many frontier scientific and technological fields such as aerospace and unmanned aerial vehicles. Their characteristics of being lightweight, easy to store and quickly deploy give them significant advantages in flight missions in complex environments. However, due to their large structural flexibility and complex modes, inflatable wings are prone to significant vibrations under aerodynamic excitation during flight, which in turn affects flight stability and control accuracy. Therefore, accurately testing and analyzing their vibration characteristics has become a crucial link in evaluating structural performance, optimizing design parameters, and ensuring flight safety.

[0003] Currently, there are some related technologies for vibration characteristic testing. For example, the "Vibration Testing Device and Vibration Simulation Method for Aircraft Wing Structures" disclosed in Chinese Patent Publication No. CN114778049A can achieve vibration transmission, clamp wing structures of different thicknesses without wearing the skin, but it is mainly aimed at aircraft wing structures and has insufficient adaptability to special structures such as inflatable wings, and does not fully consider the influence of internal air pressure changes in inflatable wings on vibration characteristics.

[0004] Another example is the "Equipment for Testing the Vibration Characteristics of Air Springs and the Method of Using the Equipment for Testing" disclosed in Chinese Patent Publication No. CN101666730A, which mainly focuses on the vibration characteristic testing of air springs. Its test object is essentially different from that of inflatable wings, and it cannot be directly applied to the vibration characteristic testing of inflatable wings in terms of testing methods and equipment applications.

[0005] In summary, in the existing related testing technologies, there are certain problems and defects in the vibration characteristic testing of inflatable wings. On the one hand, some testing methods fail to comprehensively consider the changes in the vibration characteristics of inflatable wings under different air pressure conditions, resulting in inaccurate and incomplete test data, which is difficult to meet the scientific basis requirements for wing design optimization and structural improvement. On the other hand, some testing systems are not perfect in aspects such as sensor layout, excitation method selection, and data acquisition and processing, and cannot accurately obtain key vibration characteristic parameters such as the multi-order natural frequencies and peak vibration frequencies of inflatable wings.

[0006] When solving these problems, many difficulties are faced. For example, due to the special nature of the inflatable wing structure, the mutual influence of factors such as the flexibility of its materials and the change of internal air pressure makes it necessary to fully consider how to avoid affecting the normal vibration of the wing and accurately measure during sensor arrangement; in the selection of excitation methods, the excitation effects under different working conditions and the structural safety of the wing should be taken into account; in terms of data acquisition and processing, more effective processing algorithms need to be developed for the complex vibration signals of the inflatable wing to improve the accuracy and reliability of data processing. These problems limit the in-depth research and effective application of the vibration characteristics of inflatable wings, and there is an urgent need for a test method that can comprehensively and accurately test the vibration characteristics of inflatable wings and improve the flight performance and stability of aircraft. Summary of the Invention

[0007] The technical problem to be solved by the present invention is how to comprehensively and accurately test the vibration characteristics of inflatable wings and improve the flight performance and stability of aircraft. To overcome the defects of the above prior art (or related technologies), the present invention provides a test method for the vibration characteristics of inflatable wings.

[0008] The present invention provides a test method for the vibration characteristics of inflatable wings. At least one pressure sensor is pre-installed inside the inflatable wing to be tested, a plurality of acceleration sensors are installed on the surface of the inflatable wing to be tested and the side wall of the vibration table, and each acceleration sensor is communicatively connected to an acceleration test device. A fine adjustment valve for adjusting the internal air pressure value is installed on the inflatable wing to be tested. A high-speed camera is fixedly installed beside the vibration table in advance, and the high-speed camera is electrically connected to a DIC test device. The test method for the vibration characteristics of inflatable wings includes the following steps: Step S1, randomly spray black speckles on the wing surface of the inflatable wing to be tested; Step S2, fix the inflatable wing to be tested on the vibration table and adjust the position of the high-speed camera so that the viewing angle covers the wing surface; Step S3, turn on the acceleration test device and the DIC test device, and then configure the first test parameters for the vibration table for device calibration; Step S4, configure the second test parameters for the fine adjustment valve and the vibration table to conduct a vibration sweep frequency test on the inflatable wing to be tested and record the first test data; Step S5, turn off the DIC test device, configure the third test parameters for the fine adjustment valve and the vibration table to conduct a random vibration test and record the second test data; Step S6, conduct signal data analysis and spectrum transformation on the first test data and the second test data to obtain the first few natural frequencies, vibration modes and damping ratios corresponding to the inflatable wing to be tested.

[0009] Compared with the prior art, the test method for the vibration characteristics of inflatable wings of the present invention has the following advantages: In the present invention, by synchronously integrating a pressure sensor, an acceleration sensor, an acceleration testing device, a high-speed camera, and a DIC testing device, the full-dimensional monitoring of different performances of the inflatable wing to be tested is realized, overcoming the data limitations of a single sensor. The fine-tuning valve can realize the vibration characteristic test of the inflatable wing to be tested under different internal pressure states, accurately simulate the influence of air pressure changes in actual flight on the structural stiffness of the inflatable wing to be tested, and realize the comprehensive and accurate test of the vibration characteristics of the inflatable wing. The DIC testing device provides high-precision atlas data by tracking the sprayed speckles on the wing surface, avoiding the additional mass interference of contact sensors on the flexible inflatable wing to be tested. At the same time, the step processes of device calibration, vibration sweep testing, and random vibration testing are designed to balance testing efficiency and data integrity, and can accurately analyze the first few natural frequencies, vibration modes, and damping ratios of the inflatable wing to be tested, assisting R & D personnel to correct the design parameters of the inflatable wing to be tested according to the first few natural frequencies, vibration modes, and damping ratios, thereby improving the flight performance and stability of the aircraft.

[0010] In a possible implementation manner, in step S1, a plurality of high-contrast and evenly distributed speckles with a diameter between 0.1 - 0.5 mm are randomly sprayed on the wing surface.

[0011] Compared with the prior art, adopting the above technical solution can ensure the sub-pixel displacement recognition ability of the high-speed camera under high-speed shooting through the speckles with a diameter of 0.1 - 0.5 mm, and the design of high contrast and even distribution can avoid local data loss and ensure that the images captured by the high-speed camera all contain speckles.

[0012] In a possible implementation manner, in step S2, the inflatable wing to be tested is fixed on the vibration table by using a fixture structure, and the fixture structure includes: A tooling fixture plate, which is fixed on the reference table surface of the vibration table, and a plurality of mounting holes are opened on the tooling fixture plate; An end panel, with a plurality of gaskets provided on the outer wall of the end panel, and the gaskets and the mounting holes are fixedly connected by bolts in a threaded manner; An end frame, which is arranged at the top of the end panel, and the size of the end frame is adapted to the side end size of the inflatable wing to be tested for the inflatable wing to be tested to be clamped and fixed with the end frame.

[0013] Compared with the prior art, adopting the above technical solution can avoid damaging the surface of the inflatable wing to be tested by the rigid fixture through the design of clamping by the end frame and fixing by the gasket, and can adapt to the inflatable wings to be tested with different thicknesses. At the same time, the tooling fixture plate is rigidly connected to the vibration table to ensure that the excitation signal generated by the vibration table can be transmitted to the end of the inflatable wing to be tested without loss, reducing the installation damping interference.

[0014] In a possible implementation, the number of each acceleration sensor located on the inflatable wing to be tested is ten, and each acceleration sensor is a three-axis high-precision acceleration sensor. Before performing step S1, it further includes: Paste each acceleration sensor onto the wing surface according to a 5x2 array. The five acceleration sensors in the same column are spaced 250 mm apart from each other, and the two acceleration sensors at the end far from the vibration table are 100 mm away from the wing tip.

[0015] Compared with the prior art, adopting the above technical solution can use three-axis high-precision acceleration sensors to obtain time-domain signals, reduce costs while ensuring signal coverage. The ten acceleration sensors are evenly distributed at intervals of 250 mm, which can ensure the modal vibration mode spatial resolution and avoid missing the vibration signals on the surface of the inflatable wing to be tested.

[0016] In a possible implementation, the first test parameters in step S3 are a frequency of 10 Hz, a test time of 1 min, and a cycle number of 1 time.

[0017] Compared with the prior art, adopting the above technical solution can eliminate the interference of loose installation through low-energy pre-testing and avoid damaging the unstable inflatable wing to be tested.

[0018] In a possible implementation, the second test parameters in step S4 include the first fine-tuning valve parameters and the first vibration table parameters. The first fine-tuning valve parameters include sequentially changing internal air pressure values of 10 kPa, 20 kPa, and 30 kPa, and the first vibration table parameters include a frequency of 2 - 100 Hz, power spectral density , and a test time of 5 min.

[0019] Compared with the prior art, adopting the above technical solution can perform vibration sweep testing at different internal air pressure values and obtain more comprehensive first test data.

[0020] In a possible implementation, the third test parameters in step S5 include the second fine-tuning valve parameters and the second vibration table parameters. The second fine-tuning valve parameters include sequentially changing internal air pressure values of 10 kPa, 20 kPa, 30 kPa, 40 kPa, and 50 kPa, and the second vibration table parameters include a vibration amplitude of 0.1 g, a sweep cycle of 2 min / sweep, a frequency of 4 - 100 Hz, and a cycle number of 1 time.

[0021] Compared with the prior art, adopting the above technical solution can simulate real airflow disturbances at different internal air pressure values and ensure the rationality and authenticity of the second test data.

[0022] In a possible implementation manner, the first test data includes a test image containing speckles captured by a high-speed camera and first time-domain signals output by each acceleration sensor, and the second test data includes second time-domain signals output by each acceleration sensor. In step S6, for the test image, a fast Fourier transform is performed on the displacement-time curve of the target point of the test image to perform time-domain to frequency-domain conversion to obtain a single-point amplitude-frequency diagram corresponding to the target point, and the frequency corresponding to the significant peak in the single-point amplitude-frequency diagram is identified as the natural frequency point. At the same time, for the first time-domain signal and the second time-domain signal, a frequency response function FRF diagram and a power spectral density PSD diagram are respectively constructed for the first time-domain signal and the second time-domain signal, and frequency-domain modal parameter identification is performed in the frequency response function FRF diagram and the power spectral density PSD diagram to obtain the natural frequency, damping ratio, and modal shape in the first few modes.

[0023] Compared with the prior art, adopting the above technical solution can directly obtain the natural frequency point of the local large-deformation area through the transformation from the test image to the single-point amplitude-frequency diagram, and the transformation from the time-domain signal to the frequency response function FRF diagram and the power spectral density PSD diagram can obtain the natural frequency, damping ratio, and modal shape in the first few modes through frequency-domain modal parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flowchart of the steps of the present invention; Figure 2 is a schematic structural diagram of the shaking table of the present invention; Figure 3 is a schematic structural diagram of the fixture structure of the present invention; Figure 4 is a schematic diagram of the speckles on the inflatable wing to be tested of the present invention; Figure 5 is a layout diagram of the positions of the acceleration sensors of the present invention; Figure 6 is an amplitude-frequency diagram at an internal air pressure value of 20 kPa of the present invention; Figure 7 is a poly-order natural frequency broken line diagram at different internal air pressure values of the present invention; Figure 8 is a first-order natural frequency change curve diagram at different internal air pressure values of the present invention; Figure 9 is a schematic diagram of the analysis result of the test image of the present invention; Figure 10 is a time-domain displacement diagram of the present invention, (a) is the time-domain displacement diagram in the U direction, and (b) is the time-domain displacement diagram in the V direction; Figure 11 is a schematic diagram of the first four-order modal shapes at an internal air pressure value of 20 kPa of the present invention; Description of reference numerals: 1. Inflatable wing to be tested; 2. Acceleration sensor; 3. Shaking table; 4. Tooling fixture plate; 5. Mounting hole; 6. End panel; 7. Spacer; 8. End frame. Detailed implementation manners

[0025] First of all, those skilled in the art should understand that these implementation manners are only used to explain the technical principles of the embodiments of the present invention, and are not intended to limit the protection scope of the embodiments of the present invention. Those skilled in the art can adjust them as needed to adapt to specific application scenarios.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] See Figure 1 , an embodiment of the present invention discloses a method for testing the vibration characteristics of an inflatable wing. At least one pressure sensor is pre-installed inside the inflatable wing 1 to be tested, and a plurality of acceleration sensors 2 are installed on the surface of the inflatable wing 1 to be tested, and each acceleration sensor 2 is communicatively connected to an acceleration testing device. A fine adjustment valve for adjusting the internal air pressure value is installed on the inflatable wing 1 to be tested. A high-speed camera is fixedly installed beside the shaking table 3, and the high-speed camera is electrically connected to a DIC testing device. The method for testing the vibration characteristics of the inflatable wing includes the following steps: Step S1, randomly spray black speckles on the wing surface of the inflatable wing 1 to be tested; Step S2, fix the inflatable wing 1 to be tested on the shaking table 3, and adjust the position of the high-speed camera so that the viewing angle covers the wing surface; Step S3, turn on the acceleration testing device and the DIC testing device, and then configure the first test parameters for the shaking table 3 for device calibration; Step S4, configure the second test parameters for the fine adjustment valve and the shaking table 3 to perform a vibration sweep frequency test on the inflatable wing 1 to be tested and record the first test data; Step S5, turn off the DIC testing device, configure the third test parameters for the fine adjustment valve and the shaking table 3 to perform a random vibration test and record the second test data; Step S6, perform signal data analysis and spectral transformation on the first test data and the second test data to obtain the first few natural frequencies, vibration modes, and damping ratios corresponding to the inflatable wing 1 to be tested.

[0028] In the embodiments of the present invention, the dual - system test method combining digital image correlation (DIC) technology and an acceleration sensor 2 can comprehensively and accurately obtain the vibration characteristic parameters of the inflatable wing 1 to be tested under different air pressure conditions, and can effectively obtain the full - field displacement response and local high - frequency vibration information of the inflatable wing 1 to be tested under simulated flight conditions, so as to accurately extract the key dynamic parameters such as its multi - order natural frequencies, vibration modes, and damping ratios. This test method not only improves the spatial resolution and reliability of data acquisition, but also is applicable to dynamic response analysis under various inflatable pressure boundary conditions, having good engineering application value and promotion prospects; at the same time, it realizes the full - field, non - contact, and real - time measurement of the vibration frequency of the inflatable wing 1 to be tested; makes up for the limitations of a single sensor in the test of flexible structures; can be effectively applied to the structural health monitoring, modal analysis, and design optimization of the inflatable wing 1 to be tested; provides a new technical path and experimental basis for the dynamic research of flexible aviation structures. In the design stage of a new inflatable wing aircraft, by optimizing the wing structure design through this test method, the flight performance and stability of the aircraft can be improved.

[0029] In the embodiments of the present invention, before performing step S1, the output acceleration of the vibration table 3 is pre - calibrated by comparing it with a standard accelerometer.

[0030] In the embodiments of the present invention, considering that if the internal air pressure value of the inflatable wing 1 to be tested changes, it will cause changes in the wing shape and stiffness, thereby affecting its vibration response characteristics. Therefore, in order to ensure the accuracy and reliability of the test results, the internal air pressure value of the inflatable wing 1 to be tested needs to be kept constant. In the present invention, the internal air pressure value of the inflatable wing 1 to be tested is kept constant by a fine - tuning valve, and a high - precision pressure sensor is used to real - time monitor the change of the internal air pressure value of the inflatable wing 1 to be tested, and according to the preset target air pressure value, the opening of the fine - tuning valve is automatically adjusted to achieve precise control of the gas flow. In addition, in the present invention, an electric or pneumatic actuator is used to drive the fine - tuning valve to make a fine adjustment of the opening, so as to maintain the stability of the internal air pressure value of the inflatable wing 1 to be tested during the experiment, ensuring the consistency of its structural form and experimental conditions.

[0031] In the embodiments of the present invention, the vibration table 3 is selected as the excitation method to provide controllable excitation. The end of the inflatable wing 1 to be tested is fixed on the vibration table 3 through a specific fixture structure, and the fixture structure is used to match the geometric shape of the end of the inflatable wing 1 to be tested. The vibration table 3 can apply vibrations according to the preset frequency and amplitude to simulate the dynamic load conditions of the inflatable wing 1 to be tested under actual flight conditions.

[0032] See Figure 2 and Figure 3, in step S2, the inflatable wing 1 to be tested is fixed on the shaking table 3 by a fixture structure. The fixture structure includes a tooling fixture plate 4, an end face plate 6 and an end frame 8. The tooling fixture plate 4 is fixed on the reference table surface of the shaking table 3, and a plurality of mounting holes 5 are provided on the tooling fixture plate 4; a plurality of gaskets 7 are provided on the outer wall of the end face plate 6, and the gaskets 7 and the mounting holes 5 are fixedly connected by screws; the end frame 8 is arranged at the top of the end face plate 6, and the size of the end frame 8 is adapted to the side end size of the inflatable wing 1 to be tested, so that the inflatable wing 1 to be tested is clamped and fixed with the end frame 8.

[0033] In the embodiment of the present invention, the end face plate 6 is designed in an oval shape, and 6 gaskets 7 are arranged in a ring on its outer wall, and the intervals between the gaskets 7 are the same.

[0034] In the embodiment of the present invention, the inflatable wing 1 to be tested is fixed on the shaking table 3 by a specific fixture structure, with the upper wing surface facing the vibration axis of the shaking table 3 and the lower wing surface facing the high-speed camera, which is convenient for the DIC test device to analyze the test images.

[0035] See Figure 4 , in step S1, a series of black small speckles with high contrast and evenly distributed and with a diameter of 0.1-0.5 mm are randomly sprayed on the inflatable wing 1 to be tested.

[0036] See Figure 5 , according to the structural characteristics and vibration characteristics of the inflatable wing 1 to be tested, the acceleration sensors 2 are evenly arranged on the upper wing surface of the inflatable wing 1 to be tested. Due to the light weight of the inflatable wing 1 to be tested, high-precision and low-mass acceleration sensors 2 are selected; there are a total of eleven acceleration sensors 2. Two of the acceleration sensors 2 are glued on the relatively flat surface of the inflatable wing 1 to be tested at a distance of 100 mm from the wing tip, and the spacing is 250 mm; another acceleration sensor 2 is pasted on the side wall of the shaking table 3, and the remaining eight acceleration sensors 2 are pasted on the relatively flat places of the inflatable wing 1 to be tested in turn at a longitudinal spacing of 250 mm; the above acceleration sensors 2 are connected to the acceleration test device in sequence and numbered, and the above acceleration sensors 2 all adopt three-axis high-precision acceleration sensors.

[0037] In the embodiments of the present invention, the DIC test device is specifically used to accurately measure the changes in surface displacement and strain of the inflatable wing 1 to be tested during vibration. Its derivative devices include a high-speed camera, a tripod, a lighting fill light, and image acquisition software. The high-speed camera can capture test images at a speed of thousands of frames per second to ensure a detailed record of the rapidly changing process. Turn on the high-speed camera and adjust the position of the tripod so that its position is perpendicular to the surface of the inflatable wing 1 to be tested, so that the camera view can completely cover the lower wing surface of the inflatable wing 1 to be tested. Turn on the lighting fill light, equipped with a high-quality optical lens and a uniform and stable light source. When performing light filling treatment on the surface of the inflatable wing 1 to be tested, ensure the uniform distribution of light to ensure that the test images are clear and there is no excessive reflection or shadow. Use professional image acquisition software such as Cam Record to process the acquired test image sequence. By comparing the test images at different time points, calculate the two-dimensional displacement field of each pixel point on the surface of the inflatable wing 1 to be tested. Adjust the shooting parameters of the image acquisition software to ensure the effectiveness of the test images collected in the experiment, and set its frame rate to be higher than twice the highest vibration frequency.

[0038] In an embodiment of the present invention, during specific testing, first, a high-pressure air pump is used to inflate the inflatable wing 1 to be tested, and a fine-tuning valve is used to stabilize the internal air pressure value of the inflatable wing 1 to be tested at 10 kPa. Subsequently, a high-speed camera, a lighting fill light, and image acquisition software are turned on. The position of the tripod is adjusted for position calibration, the shooting parameters are adjusted, and an acceleration sensor 2 is connected to the input port of a multi-channel data signal acquisition system using an appropriate cable. The DHDAS data acquisition software is opened, and channel parameters such as the sensor range, sensitivity, and filter are set. The multi-sensor data synchronous acquisition function is enabled to ensure that the data acquisition time of all sensor channels is the same. The trigger condition is set to automatic trigger. In modal analysis, each acceleration sensor 2 is numbered, the acceleration test device and the DIC test device are started synchronously, the power switch of the shaker 3 is turned on, and after waiting for the power amplifier to complete self-checking, the gain setting is adjusted. The control panel of the shaker 3 is opened, the frequency of fixed-frequency dwell is set to 10 Hz, the test time is set to 1 min, the number of cycles is set to 1 time, and the trigger condition is set to automatic trigger. The shaker 3 is started, the DIC test device and the acceleration test device are calibrated to ensure that the inflatable wing 1 to be tested is stably clamped, and data is recorded synchronously; subsequently, the internal air pressure value of the inflatable wing to be tested is adjusted to 10 kPa, 20 kPa, and 30 kPa in sequence by adjusting the opening degree of the fine-tuning valve. The shaker 3 is set with a vibration amplitude of 0.1 g, a sweep frequency of 2 min / sweep, a frequency range of 4 - 100 Hz, and the number of cycles is set to 1 time to perform a vibration sweep test on the inflatable wing 1 to be tested, and the two test devices record data synchronously; subsequently, the DIC test device is turned off, and the internal air pressure value of the inflatable wing 1 to be tested is adjusted to 10 kPa, 20 kPa, 30 kPa, 40 kPa, and 50 kPa in sequence by adjusting the opening degree of the fine-tuning valve. The shaker 3 is set at a frequency of 2 - 100 Hz, and the power spectral density , the test time is 5 min, and a random vibration test is performed. The time-domain signal measured by the acceleration sensor 2 is used by signal analysis software to construct a frequency response function FRF diagram and a power spectral density PSD diagram. Frequency-domain modal parameter identification is performed in the frequency response function FRF diagram and the power spectral density PSD diagram, and the natural frequency, damping ratio, and modal vibration mode in the first few modes of the inflatable wing 1 to be tested can be obtained; after the test is completed, the shaker 3, the power amplifier, the high-speed camera, the DIC test device, and the acceleration test device are turned off in sequence.

[0039] In an embodiment of the present invention, the first test data includes the test images containing speckles taken by the high-speed camera and the first time-domain signals output by each acceleration sensor 2, and the second test data includes the second time-domain signals output by each acceleration sensor 2. In step S6, for the test images, 1000 images of a certain speckle point in the test images are selected. After image denoising, distortion correction, and matching by the DIC image analysis program, the time-domain displacement diagram of this speckle is processed, as Figure 10As shown, a fast Fourier transform is performed on the displacement time series of the target points in the test image for time-frequency domain conversion to obtain the single-point amplitude-frequency diagram corresponding to the target points, and the frequency corresponding to the significant peak in the single-point amplitude-frequency diagram is identified as the natural frequency point. At the same time, for the first time-domain signal and the second time-domain signal, the time-domain signal output by the acceleration sensor 2 on the vibration table 3 is used as the input signal, and the time-domain signals output by the remaining acceleration sensors 2 are used as the output signals. The frequency response function FRF diagram and the power spectral density PSD diagram are constructed for the first time-domain signal and the second time-domain signal respectively, and the frequency-domain modal parameters are identified in the frequency response function FRF diagram and the power spectral density PSD diagram. The specific steps are as follows: The peak picking method is used to locate the resonance frequency in the amplitude spectrum as the natural frequency, the half-power bandwidth method is used to calculate the damping ratio, and the modal shape is solved based on the multi-reference point least squares complex frequency domain method (Poly MAX). After verifying the orthogonality of the modal shapes through the modal confidence criterion (MAC matrix), the natural frequency, damping ratio, and modal shape of the first few modes of the inflatable wing 1 to be tested can be obtained.

[0040] In the embodiment of the present invention, by performing frequency response function FRF estimation and power spectral density PSD analysis on the time-domain signal, an amplitude-frequency diagram can be obtained. For the partial frequency response data of the internal air pressure value of 20 kPa, refer to Figure 6 From this, the natural frequencies of the first few orders under different internal air pressure values can be calculated from the steady-state diagram. For the order-natural frequency broken line diagram under different internal air pressure values, refer to Figure 7 Among them, the curves A, B, C, D, and E from top to bottom respectively correspond to the internal air pressure values of 50 kPa, 40 kPa, 30 kPa, 20 kPa, and 10 kPa. For the first-order natural frequency change curve diagram under different internal air pressure values, refer to Figure 8 For the first four-order modal shapes under the internal air pressure value of 20 kPa, refer to Figure 11 The list of the first four-order modal damping ratios under the internal air pressure value of 20 kPa is shown in Table 1 below: Table 1 List of the first four-order modal damping ratios under the internal air pressure value of 20 kPa 。

[0041] In the embodiment of the present invention, the image analysis result is obtained by analyzing the test image. Refer to Figure 9 The change of the displacement of each point on the surface of the inflatable wing 1 to be tested with time can be calculated. Refer to Figure 10 , (a) is the time-domain displacement diagram in the U direction, and (b) is the time-domain displacement diagram in the V direction. Then, a fast Fourier transform (FFT) is performed on the displacement time series of a specific target point, so as to convert the data to the frequency domain, and the frequency corresponding to the significant peak in the amplitude-frequency diagram is identified as the natural frequency point of the inflatable wing 1 to be tested.

[0042] In the description of the present invention, the description referring to terms such as "one embodiment", "some embodiments", "in this embodiment", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0043] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for testing the vibration characteristics of an inflatable wing, characterized in that, At least one pressure sensor is pre-installed inside the inflatable wing to be tested. A plurality of acceleration sensors are installed on the surface of the inflatable wing to be tested and the side wall of the vibration table, and each acceleration sensor is communicatively connected to an acceleration testing device. A fine-tuning valve for adjusting the internal air pressure value is installed on the inflatable wing to be tested. A high-speed camera is fixedly installed beside the vibration table, and the high-speed camera is electrically connected to a DIC testing device. The method for testing the vibration characteristics of the inflatable wing includes the following steps: Step S1, randomly spray speckles in a black shape on the wing surface of the inflatable wing to be tested; Step S2, fix the inflatable wing to be tested on the vibration table, and adjust the position of the high-speed camera until the viewing angle covers the wing surface; Step S3, turn on the acceleration testing device and the DIC testing device, and then configure the first test parameters for the vibration table for device calibration; Step S4, configure the second test parameters for the fine-tuning valve and the vibration table to conduct a vibration sweep test on the inflatable wing to be tested and record the first test data; Step S5, turn off the DIC testing device, configure the third test parameters for the fine-tuning valve and the vibration table to conduct a random vibration test and record the second test data; Step S6, perform signal data analysis and spectrum transformation on the first test data and the second test data to obtain the first few natural frequencies, vibration modes, and damping ratios corresponding to the inflatable wing to be tested.

2. The method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that In step S1, a plurality of speckles with high contrast and evenly distributed and with diameters between 0.1 - 0.5 mm are randomly sprayed on the wing surface.

3. The method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that In step S2, the inflatable wing to be tested is fixed on the vibration table by using a fixture structure, and the fixture structure includes: A tooling fixture plate, fixed on the reference table surface of the vibration table, and a plurality of mounting holes are provided on the tooling fixture plate; An end panel, with a plurality of gaskets provided on the outer wall of the end panel, and the gaskets and the mounting holes are fixedly connected by screws; An end frame, provided at the top of the end panel, and the size of the end frame is adapted to the side end size of the inflatable wing to be tested for the inflatable wing to be tested to be clamped and fixed with the end frame.

4. A method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that, The number of each acceleration sensor located on the inflatable wing to be tested is ten, and each acceleration sensor is a three-way high-precision acceleration sensor. Then, before performing step S1, it further includes: Paste each acceleration sensor to the wing surface according to a 5x2 array. The five acceleration sensors in the same column are spaced 250 mm apart from each other, and the two acceleration sensors at the end far from the vibration table are 100 mm away from the wing tip.

5. A method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that The first test parameters in step S3 are a frequency of 10 Hz, a test time of 1 min, and a cycle number of 1 time.

6. The method for testing the vibration characteristics of an inflatable wing according to claim 1, wherein, The second test parameters in step S4 include the first fine-tuning valve parameter and the first vibration table parameter. The first fine-tuning valve parameter includes sequentially changing internal air pressure values of 10 kPa, 20 kPa, and 30 kPa. The first vibration table parameter includes a frequency of 2 - 100 Hz and a power spectral density , and a test time of 5 min.

7. A method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that The third test parameters in step S5 include second fine-tuning valve parameters and second vibration table parameters. The second fine-tuning valve parameters include sequentially changing internal air pressure values of 10 kPa, 20 kPa, 30 kPa, 40 kPa, and 50 kPa, and the second vibration table parameters include a vibration amplitude of 0.1 g, a sweep cycle of 2 min / sweep, a frequency of 4 - 100 Hz, and a cycle number of 1 time.

8. A method for testing the vibration characteristics of an inflatable wing according to claim 1, characterized in that The first test data includes the test images containing speckles captured by a high-speed camera and the first time-domain signals output by each acceleration sensor. The second test data includes the second time-domain signals output by each acceleration sensor. In step S6, for the test images, a fast Fourier transform is performed on the displacement-time curve of the target points of the test images to perform time-domain to frequency-domain conversion to obtain the single-point amplitude-frequency diagram corresponding to the target points, and the frequency corresponding to the significant peak in the single-point amplitude-frequency diagram is identified as the natural frequency point. At the same time, for the first time-domain signal and the second time-domain signal, a frequency response function FRF diagram and a power spectral density PSD diagram are respectively constructed for the first time-domain signal and the second time-domain signal, and the natural frequency, damping ratio, and mode shape in the first few modes are identified by performing frequency-domain modal parameter identification in the frequency response function FRF diagram and the power spectral density PSD diagram.

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