A method for testing vibration characteristics of inflatable wings

Abstract

The present invention provides a method for testing the vibration characteristics of an inflatable wing, comprising: step S1, spraying speckles on the surface of the inflatable wing to be tested; step S2, fixing the inflatable wing to be tested on a vibration table, and adjusting a high-speed camera to cover the wing surface; step S3, turning on an acceleration test device and a DIC test device, and calibrating the vibration table by configuring a first test parameter; step S4, performing a vibration sweep test on a fine-tuning valve and a vibration table configured with a second test parameter to obtain first test data; step S5, turning off the DIC test device, performing a random vibration test on the fine-tuning valve and the vibration table configured with a third test parameter, and recording second test data; and step S6, performing signal data analysis and spectrum conversion on the first and second test data to obtain the first several natural frequencies, vibration modes, and damping ratios of the inflatable wing to be tested. The beneficial effect is that the present invention can comprehensively and accurately test the vibration characteristics of an inflatable wing, thereby improving 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 in particular to a method for testing the vibration characteristics of an inflatable wing. Background Art

[0002] Inflatable wings hold broad application prospects in a variety of cutting-edge technology fields, including aerospace and drones. Their lightweight structure, ease of storage, and rapid deployment give them significant advantages in flight missions in complex environments. However, due to their high structural flexibility and complex modal structures, inflatable wings are susceptible to aerodynamic excitation during flight, generating significant vibrations that can affect flight stability and control accuracy. Therefore, accurate testing and analysis of their vibration characteristics are crucial for evaluating structural performance, optimizing design parameters, and ensuring flight safety.

[0003] At present, there are some related technologies for vibration characteristic testing, such as the "A vibration testing device and vibration simulation method for aircraft wing surface structures" mentioned in Chinese patent publication No. CN114778049A. Although this vibration testing device can realize vibration transmission and clamp wing surface structures of different thicknesses without wearing the surface, it is mainly aimed at aircraft wing surface structures. It is not adaptable to the special structure of inflatable wings and does not fully consider the impact of internal air pressure changes of inflatable wings on vibration characteristics.

[0004] For example, the "Equipment for testing the vibration characteristics of air springs and the method for testing using the same" involved in Chinese patent publication No. CN101666730A mainly focuses on the vibration characteristics testing of air springs. Its test objects are essentially different from inflatable wings, and the test methods and equipment applications cannot be directly applied to the vibration characteristics testing of inflatable wings.

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

[0006] There are many difficulties in solving these problems. For example, due to the special structure of the inflatable wing, factors such as material flexibility and internal air pressure changes affect each other, making it necessary to fully consider how to avoid affecting the normal vibration of the wing and accurately measure it when arranging the sensors. When choosing the excitation method, it is necessary to take into account the excitation effect and wing structural safety under different working conditions. In terms of data acquisition and processing, it is necessary to develop more effective processing algorithms for the complex vibration signals of the inflatable wing to improve the accuracy and reliability of data processing. These problems have limited the in-depth research and effective application of the vibration characteristics of the inflatable wing. There is an urgent need for a test method that can comprehensively and accurately test the vibration characteristics of the inflatable wing and improve the flight performance and stability of the 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. In order to overcome the defects of the above-mentioned existing technologies (or related technologies), the present invention provides a method for testing the vibration characteristics of inflatable wings.

[0008] The present invention provides a method for testing the vibration characteristics of an inflatable wing. The method comprises the following steps: installing at least one pressure sensor inside the inflatable wing to be tested; installing multiple acceleration sensors on the surface of the inflatable wing to be tested and on the sidewalls of a 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 next to the vibration table and is electrically connected to a DIC testing device. The method comprises the following steps:

[0009] Step S1, randomly spraying black speckles on the wing surface of the inflatable wing to be tested;

[0010] Step S2, fixing the inflatable wing to be tested on a vibration table, and adjusting the position of the high-speed camera to cover the wing surface;

[0011] Step S3, turning on the acceleration test device and the DIC test device, and then configuring the vibration table with the first test parameters to perform device calibration;

[0012] Step S4, configuring the fine-tuning valve and the vibration table with second test parameters to perform a vibration sweep test on the inflatable wing to be tested and record the first test data;

[0013] Step S5, closing the DIC test device, performing a random vibration test on the fine-tuning valve and the vibration table with the third test parameters configured, and recording the second test data;

[0014] Step S6: performing signal data analysis and spectrum conversion on the first test data and the second test data to obtain the first several orders of natural frequencies, vibration modes and damping ratios corresponding to the inflatable wing to be tested.

[0015] Compared with the prior art, the inflatable wing vibration characteristics testing method of the present invention has the following advantages:

[0016] The present invention achieves full-dimensional monitoring of the different performances of the inflatable wing to be tested by synchronously integrating a pressure sensor, an acceleration sensor, an acceleration test device, a high-speed camera, and a DIC test device, 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 simulating the impact of air pressure changes in actual flight on the structural stiffness of the inflatable wing to be tested, and achieving comprehensive and accurate testing of the vibration characteristics of the inflatable wing. The DIC test device provides high-precision atlas data by image tracking the sprayed speckles on the wing surface, avoiding the interference of the contact sensor on the additional mass of the flexible inflatable wing to be tested. At the same time, the step-by-step process design of the device calibration, vibration sweep test, and random vibration test takes into account both test 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 in correcting the design parameters of the inflatable wing to be tested based on the first few natural frequencies, vibration modes and damping ratios, thereby improving the flight performance and stability of the aircraft.

[0017] In a possible implementation, in step S1 , a plurality of high-contrast and evenly distributed speckles with a diameter between 0.1 and 0.5 mm are randomly sprayed on the airfoil.

[0018] Compared with the existing technology, the above technical solution can ensure the sub-pixel displacement recognition capability of the height camera under high-speed shooting through speckle with a diameter of 0.1-0.5mm. The high-contrast and uniformly distributed design can avoid local data loss and ensure that the speckle is included in the image taken by the high-speed camera.

[0019] In one possible implementation, in step S2, the inflatable wing to be tested is fixed on a vibration table using a fixture structure, the fixture structure comprising:

[0020] A fixture plate is fixed on the reference table of the vibration table, and a plurality of mounting holes are opened on the fixture plate;

[0021] An end panel, wherein a plurality of gaskets are provided on the outer wall of the end panel, and the gaskets are threadedly connected and fixed to the mounting holes by bolts;

[0022] An end frame is arranged at the top end of the end panel. The size of the end frame is adapted to the side end size of the inflatable wing to be tested so that the inflatable wing to be tested can be engaged and fixed with the end frame.

[0023] Compared with the existing technology, the above technical solution can avoid the rigid fixture from damaging the surface of the inflatable wing to be tested through the design of end frame clamping and gasket fixing, and can adapt to inflatable wings to be tested of different thicknesses. At the same time, the tooling fixture plate is rigidly connected to the vibration table, ensuring that the excitation signal emitted by the vibration table can be transmitted to the end of the inflatable wing to be tested without loss, thereby reducing installation damping interference.

[0024] In a possible implementation, the number of acceleration sensors located on the inflatable wing to be tested is ten, and each acceleration sensor is a three-axis high-precision acceleration sensor. Before executing step S1, the following steps may be further included:

[0025] The accelerometers were affixed to the wing surface in a 5x2 array. The five accelerometers in the same row were spaced 250 mm apart. The two accelerometers at the end away from the vibration table were 100 mm away from the wingtip.

[0026] Compared with the existing technology, the above technical solution can use three-way high-precision acceleration sensors to obtain time domain signals, ensuring signal coverage while reducing costs. The ten acceleration sensors are evenly distributed at 250mm intervals, which can ensure the spatial resolution of the modal vibration shape and avoid missing the vibration signal on the surface of the inflatable wing to be tested.

[0027] In a possible implementation, the first test parameters in step S3 are a frequency of 10 Hz, a test time of 1 minute, and a cycle number of 1.

[0028] Compared with the existing technology, the above technical solution can eliminate the interference of loose installation through low-energy pre-testing and avoid damage to the unstable inflatable wing to be tested.

[0029] In one possible embodiment, the second test parameter in step S4 includes a first fine-tuning valve parameter and a first vibration table parameter, wherein the first fine-tuning valve parameter includes sequentially transformed internal air pressure values ​​of 10kPa, 20kPa, and 30kPa, and the first vibration table parameter includes a frequency of 2-100Hz, a power spectrum density, and a frequency of 100-100Hz. , test time: 5 minutes.

[0030] Compared with the existing technology, the above technical solution can realize vibration frequency sweep testing under different internal air pressure values ​​and obtain more comprehensive first test data.

[0031] In one possible embodiment, 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 internal air pressure values ​​of 10kPa, 20kPa, 30kPa, 40kPa and 50kPa that are transformed in sequence, and the second vibration table parameters include vibration amplitude of 0.1g, sweep cycle of 2min / sweep, frequency of 4-100Hz, and number of cycles of 1 time.

[0032] Compared with the existing technology, the above technical solution can realize the simulation of real airflow disturbance under different internal air pressure values, thereby ensuring the rationality and authenticity of the second test data.

[0033] In one possible embodiment, the first test data includes a test image containing speckle captured by a high-speed camera and a first time domain signal output by each acceleration sensor, and the second test data includes a second time domain signal output by each acceleration sensor. In step S6, a fast Fourier transform is performed on a displacement-time curve of a target point in the test image to perform a time-domain-frequency conversion to obtain a single-point amplitude-frequency diagram corresponding to the target point, and a frequency corresponding to a significant peak in the single-point amplitude-frequency diagram is identified as a natural frequency point. Simultaneously, a frequency response function (FRF) diagram and a power spectral density (PSD) diagram are constructed for the first time domain signal and the second time domain signal, respectively. Frequency domain modal parameters are identified in the frequency response function (FRF) diagram and the power spectral density (PSD) diagram to obtain natural frequencies, damping ratios, and modal vibration shapes of the first several modes.

[0034] Compared with the existing technology, the above technical solution can directly obtain the natural frequency points of the local large deformation area by transforming the test image into a single-point amplitude-frequency diagram, while the transformation of the time domain signal into the frequency response function FRF diagram and the power spectrum density PSD diagram can obtain the natural frequency, damping ratio and modal vibration shape of the first few modes through frequency domain modal parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the steps of the present invention;

[0036] Figure 2 It is a structural schematic diagram of the vibration table of the present invention;

[0037] Figure 3 It is a structural schematic diagram of the clamp structure of the present invention;

[0038] Figure 4 is a schematic diagram of speckles on the inflatable wing to be tested according to the present invention;

[0039] Figure 5 A diagram showing the arrangement of the acceleration sensors of the present invention;

[0040] Figure 6This is the amplitude-frequency diagram of the present invention at an internal air pressure value of 20 kPa;

[0041] Figure 7 It is a multi-order natural frequency broken line graph under different internal air pressure values ​​of the present invention;

[0042] Figure 8 is a graph showing the change of the first-order natural frequency at different internal air pressure values ​​of the present invention;

[0043] Figure 9 Schematic diagram of the analysis results of the test image of the present invention;

[0044] Figure 10 The time domain displacement diagram of the present invention, (a) is the time domain displacement diagram in the U direction, (b) is the time domain displacement diagram in the V direction;

[0045] Figure 11 Schematic diagram of the first four modal vibration shapes of the present invention at an internal air pressure of 20 kPa;

[0046] Explanation of the accompanying symbols: 1. inflatable wing to be tested; 2. acceleration sensor; 3. vibration table; 4. fixture plate; 5. mounting hole; 6. end panel; 7. gasket; 8. end frame. DETAILED DESCRIPTION

[0047] First, those skilled in the art should understand that these embodiments are merely for explaining the technical principles of the embodiments of the present invention and are not intended to limit the scope of protection of the embodiments of the present invention. Those skilled in the art may make adjustments as needed to adapt to specific application scenarios.

[0048] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] See also Figure 1 The 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. Multiple 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-tuning 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 next to a vibration table 3, and the high-speed camera is electrically connected to a DIC testing device. The method for testing the vibration characteristics of an inflatable wing includes the following steps:

[0050] Step S1, randomly spraying black speckles on the wing surface of the inflatable wing to be tested 1;

[0051] Step S2, fixing the inflatable wing 1 to be tested on the vibration table 3, and adjusting the position of the high-speed camera to cover the wing surface;

[0052] Step S3, turning on the acceleration test device and the DIC test device, and then configuring the first test parameters on the vibration table 3 to perform device calibration;

[0053] Step S4, configuring the fine-tuning valve and the vibration table 3 with second test parameters to perform a vibration sweep test on the inflatable wing 1 to be tested and record the first test data;

[0054] Step S5, closing the DIC test device, configuring the third test parameters for the fine-tuning valve and the vibration table 3 to perform a random vibration test and record the second test data;

[0055] Step S6: performing signal data analysis and spectrum conversion on the first test data and the second test data to obtain the first several orders of natural frequencies, vibration modes, and damping ratios corresponding to the inflatable wing 1 to be tested.

[0056] In an embodiment of the present invention, a dual-system testing method based on the combination of 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. It 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, thereby accurately extracting its key dynamic parameters such as multi-order natural frequencies, vibration modes, and damping ratios. This testing method not only improves the spatial resolution and reliability of data acquisition, but is also applicable to dynamic response analysis under various inflation pressure boundary conditions, and has excellent engineering application value and promotion prospects. At the same time, it achieves full-field, non-contact, and real-time measurement of the vibration frequency of the inflatable wing 1 to be tested, thereby overcoming the limitations of a single sensor in flexible structure testing. It can be effectively applied to structural health monitoring, modal analysis, and design optimization of the inflatable wing 1 to be tested, providing a new technical path and experimental basis for the dynamic research of flexible aviation structures. During the design phase of a new inflatable wing aircraft, optimizing the structural design of the wing through this testing method can improve the flight performance and stability of the aircraft.

[0057] In the embodiment of the present invention, before executing step S1 , the output acceleration of the vibration table 3 is preliminarily compared and calibrated using a standard accelerometer.

[0058] In an embodiment of the present invention, considering that if the internal air pressure value of the inflatable wing 1 to be tested changes, the wing shape and stiffness will change, thereby affecting its vibration response characteristics, 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 remain unchanged. 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 monitor the changes in the internal air pressure value of the inflatable wing 1 to be tested in real time. 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 rate. In addition, in the present invention, an electric or pneumatic actuator is used to drive the fine-tuning valve to make subtle adjustments to the opening, thereby maintaining the internal air pressure value of the inflatable wing 1 to be tested stable during the experiment, ensuring the consistency of its structural morphology and experimental conditions.

[0059] In an embodiment of the present invention, a 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 by a specific clamp structure. The clamp 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 vibration according to a preset frequency and amplitude to simulate the dynamic load conditions of the inflatable wing 1 to be tested under actual flight conditions.

[0060] See also Figure 2 and Figure 3 In step S2, the inflatable wing 1 to be tested is fixed on the vibration table 3 using a fixture structure. The fixture structure includes a tooling fixture plate 4, an end panel 6 and an end frame 8. The tooling fixture plate 4 is fixed to the reference table surface of the vibration table 3. A plurality of mounting holes 5 are opened on the tooling fixture plate 4; a plurality of gaskets 7 are provided on the outer wall of the end panel 6, and the gaskets 7 and the mounting holes 5 are threadedly connected and fixed by bolts; the end frame 8 is provided at the top end of the end panel 6. The size of the end frame 8 is adapted to the size of the side end of the inflatable wing 1 to be tested, so that the inflatable wing 1 to be tested can be engaged and fixed with the end frame 8.

[0061] In the embodiment of the present invention, the end panel 6 is designed to be elliptical, and six gaskets 7 are arranged on the outer wall thereof, and the intervals between the gaskets 7 are the same.

[0062] In the embodiment of the present invention, the inflatable wing 1 to be tested is fixed on the vibration table 3 by a specific clamp structure, with the upper wing surface facing the vibration axis of the vibration table 3 and the lower wing surface facing the high-speed camera, so that the DIC test device can analyze the test image conveniently.

[0063] See also Figure 4 In step S1, a series of high-contrast, evenly distributed black small specks with a diameter of 0.1-0.5 mm are randomly sprayed on the inflatable wing 1 to be tested.

[0064] See also Figure 5According 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 lightweight characteristics of the inflatable wing 1 to be tested, high-precision, low-mass acceleration sensors 2 are selected; there are a total of eleven acceleration sensors 2, two of which are glued to the relatively flat surface of the inflatable wing 1 to be tested at a distance of 100 mm from the wing tip, with a spacing of 250 mm; another acceleration sensor 2 is glued to the side wall of the vibration table 3, and the remaining eight acceleration sensors 2 are sequentially glued to the relatively flat part of the inflatable wing 1 to be tested with a longitudinal spacing of 250 mm; the above acceleration sensors 2 are connected to the acceleration testing device in sequence and numbered, and the above acceleration sensors 2 all use three-axis high-precision acceleration sensors.

[0065] In an embodiment of the present invention, a 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, an illumination 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 detailed recording of the rapidly changing process. The high-speed camera is turned on, and the position of the tripod is adjusted so that its position is perpendicular to the surface of the inflatable wing 1 to be tested, so that the camera angle of view can completely cover the lower wing surface of the inflatable wing 1 to be tested. The illumination fill light is turned on, equipped with a high-quality optical lens and a uniform and stable light source. When illuminating the surface of the inflatable wing 1 to be tested, the uniform distribution of light should be ensured to ensure that the test image is clear and free of excessive reflections or shadows. Professional image acquisition software such as Cam Record is used to process the collected test image sequence, and by comparing the test images at different time points, the two-dimensional displacement field of each pixel point on the surface of the inflatable wing 1 to be tested is calculated. The shooting parameters of the image acquisition software are adjusted to ensure that the test images collected in the experiment are valid, and its frame rate is set to be higher than 2 times the highest vibration frequency.

[0066] In an embodiment of the present invention, when conducting a specific test, a high-pressure air pump is first used to inflate the inflatable wing 1 to be tested, and the internal air pressure value of the inflatable wing 1 to be tested is stabilized to 10 kPa by a fine-tuning valve. Subsequently, the high-speed camera, the lighting fill light, and the image acquisition software are turned on, the position of the tripod is adjusted for position accuracy, the shooting parameters are adjusted, the acceleration sensor 2 is connected to the input port of the multi-channel data signal acquisition system using an appropriate cable, the DHDAS data acquisition software is opened, the sensor range, sensitivity, filter and other channel parameters are set, the multi-sensor data synchronous acquisition function is enabled, the data acquisition time of all sensor channels is ensured to be consistent, the trigger condition is set to automatic triggering, each acceleration sensor 2 is numbered in the modal analysis, the acceleration test device and the DIC test device are started synchronously, the power switch of the vibration table 3 is turned on, the power amplifier is turned on and waits for the self-test to be completed, the gain setting is adjusted, and the control panel of the vibration table 3 is opened. , set the fixed-frequency dwell frequency to 10Hz, the test time to 1min, the number of cycles to 1, the trigger condition to automatic trigger, start the vibration table 3, calibrate the DIC test device and the acceleration test device to ensure that the inflatable wing 1 to be tested is clamped stably, and record the data synchronously; then adjust the internal air pressure of the inflatable wing to be tested to 10kPa, 20kPa, and 30kPa by adjusting the opening of the fine-tuning valve, set the vibration amplitude of the vibration table 3 to 0.1g, the sweep cycle to 2min / sweep, the frequency range to 4-100Hz, and the number of cycles to 1. Perform a vibration sweep test on the inflatable wing 1 to be tested, and the dual test devices record the data synchronously; then turn off the DIC test device, and adjust the internal air pressure of the inflatable wing to be tested to 10kPa, 20kPa, 30kPa, 40kPa, and 50kPa by adjusting the opening of the fine-tuning valve. The vibration table 3 is set at a frequency of 2-100Hz, and the power spectral density The test time is 5 minutes. A random vibration test is performed. The time domain signal measured by the acceleration sensor 2 is used to construct a frequency response function FRF diagram and a power spectrum density PSD diagram using signal analysis software. The frequency domain modal parameters are identified in the frequency response function FRF diagram and the power spectrum density PSD diagram. The natural frequencies, damping ratios and modal vibration shapes of the first several modes of the inflatable wing 1 to be tested can be obtained. After the test, the vibration table 3, power amplifier, high-speed camera, DIC test device and acceleration test device are turned off in sequence.

[0067] In the embodiment of the present invention, the first test data includes a test image containing speckle captured by a high-speed camera and a first time-domain signal output by each acceleration sensor 2. The second test data includes a second time-domain signal output by each acceleration sensor 2. In step S6, 1000 images of a speckle in the test image are selected. After image denoising, distortion correction, and matching, a DIC image analysis program is used to obtain a time-domain displacement map of the speckle, as shown in FIG. Figure 10As shown, a fast Fourier transform is performed on the displacement time series of the target point in the test image to perform time-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, 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 spectrum 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 spectrum density PSD diagram. The specific steps are as follows: the resonant frequency is located as the natural frequency in the amplitude spectrum using the peak picking method, the damping ratio is calculated using the half-power bandwidth method, and the modal vibration shape is solved based on the multi-reference point least squares complex frequency domain method (Poly MAX). After the orthogonality of the vibration shape is verified by the modal confidence criterion (MAC matrix), the natural frequency, damping ratio and modal vibration shape of the first few modes of the inflatable wing 1 to be tested can be obtained.

[0068] In the embodiment of the present invention, the frequency response function FRF estimation and power spectrum density PSD analysis are performed on the time domain signal to obtain an amplitude-frequency diagram. For partial frequency response data of the internal pressure value of 20kPa, see Figure 6 From the steady-state diagram, the natural frequencies of the first few orders at different internal pressure values ​​can be calculated. The order-natural frequency line graph at different internal pressure values ​​can be found in Figure 7 From top to bottom, curves A, B, C, D, and E correspond to internal pressure values ​​of 50kPa, 40kPa, 30kPa, 20kPa, and 10kPa, respectively. For the first-order natural frequency change curves at different internal pressure values, see Figure 8 , the first four modal vibration shapes at 20kPa internal pressure are shown in Figure 11 , the damping ratios of the first four modes at an internal pressure of 20kPa are shown in Table 1 below:

[0069] Table 1 List of damping ratios of the first four modes at an internal pressure of 20 kPa

[0070] .

[0071] In the embodiment of the present invention, the test image is analyzed to obtain the image analysis result, see Figure 9 , the displacement of each point on the surface of the inflatable wing 1 to be tested can be calculated over time, see 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, the displacement time series of the specific target point is subjected to fast Fourier transform (FFT) to convert the data into the frequency domain, from which 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.

[0072] In the description of the present invention, the reference terms "one embodiment", "some embodiments", "in the present embodiment", "specific examples", or "some examples" mean that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0073] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection 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; multiple acceleration sensors are installed on the surface of the inflatable wing to be tested and on the side walls 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 next to the vibration table, and the high-speed camera is electrically connected to the DIC testing device. The method for testing the vibration characteristics of the inflatable wing includes the following steps: Step S1, randomly spraying black speckles on the wing surface of the inflatable wing to be tested; Step S2, fixing the inflatable wing to be tested on a vibration table, and adjusting the position of the high-speed camera to cover the wing surface; Step S3, turning on the acceleration test device and the DIC test device, and then configuring the vibration table with the first test parameters to perform device calibration; Step S4, configuring the fine-tuning valve and the vibration table with second test parameters to perform a vibration sweep test on the inflatable wing to be tested and record the first test data; Step S5, closing the DIC test device, performing a random vibration test on the fine-tuning valve and the vibration table with the third test parameters configured, and recording the second test data; Step S6: performing signal data analysis and spectrum conversion on the first test data and the second test data to obtain the first several orders of natural frequencies, vibration modes and damping ratios corresponding to the inflatable wing to be tested.

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

3. The method for testing 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 using a fixture structure, and the fixture structure includes: A fixture plate is fixed on the reference table of the vibration table, and a plurality of mounting holes are opened on the fixture plate; An end panel, wherein a plurality of gaskets are provided on the outer wall of the end panel, and the gaskets are threadedly connected and fixed to the mounting holes by bolts; An end frame is arranged at the top end of the end panel. The size of the end frame is adapted to the side end size of the inflatable wing to be tested so that the inflatable wing to be tested can be engaged and fixed with the end frame.

4. The method for testing vibration characteristics of an inflatable wing according to claim 1, characterized in that: There are ten acceleration sensors located on the inflatable wing to be tested, and each acceleration sensor is a three-axis high-precision acceleration sensor. Before executing step S1, the following steps are also included: The accelerometers were affixed to the wing surface in a 5x2 array. The five accelerometers in the same row were spaced 250 mm apart. The two accelerometers at the end away from the vibration table were 100 mm away from the wingtip.

5. The method for testing 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 minute, and a cycle number of 1.

6. The method for testing vibration characteristics of an inflatable wing according to claim 1, characterized in that: 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 the internal air pressure values ​​10kPa, 20kPa, and 30kPa that are sequentially changed. The first vibration table parameters include the frequency 2-100Hz, the power spectrum density , test time: 5 minutes.

7. The method for testing 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 internal air pressure values ​​of 10kPa, 20kPa, 30kPa, 40kPa and 50kPa that are changed in sequence. The second vibration table parameters include vibration amplitude of 0.1g, sweep cycle of 2min / sweep, frequency of 4-100Hz, and number of cycles of 1 time.

8. The method for testing vibration characteristics of an inflatable wing according to claim 1, characterized in that: The first test data includes a test image containing speckle captured by a high-speed camera and a first time domain signal output by each acceleration sensor. The second test data includes a second time domain signal output by each acceleration sensor. In step S6, a fast Fourier transform is performed on the displacement time curve of a target point in the test image to perform a time-domain-frequency conversion to obtain a single-point amplitude-frequency diagram corresponding to the target point, and the frequency corresponding to a significant peak in the single-point amplitude-frequency diagram is identified as a natural frequency point. At the same time, a frequency response function (FRF) diagram and a power spectral density (PSD) diagram are constructed for the first time domain signal and the second time domain signal, respectively. Frequency domain modal parameters are identified in the frequency response function (FRF) diagram and the power spectral density (PSD) diagram to obtain the natural frequencies, damping ratios, and modal vibration shapes of the first several modes.

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