Guided wave A0 modal-based full-area multi-layered damage imaging method for reinforced beam structure

Abstract

The invention discloses a guided wave A0 modal-based full-area multi-layered damage imaging method for a reinforced beam structure. The method comprises the following steps: generating an A0 modal guided wave signal through a laser non-contact scanning system, spreading the A0 modal guided wave signal in a composite reinforced beam structure, detecting a two-dimensional guided wave response signal, performing signal filtering processing, setting a specific window function, extracting an A0 modal wave field two-dimensional data set in a filtering signal, and converting the A0 modal wave field two-dimensional data set into a three-dimensional data set; and constructing a specific full-region multi-layered damage imaging model, obtaining an A0 modal wave field curvature, inputting the A0 modal wave field curvature into the model for processing, and outputting imaging results of different types of layered damage. According to the method, layering damage detection can be carried out on the large-scale reinforced beam structure, the detection efficiency of the large-scale composite material reinforced beam structure is improved, and an idea is provided for realizing automatic detection.

Description

Technical Field

[0001] The present invention relates to a method for imaging damage of a reinforced beam structure, and relates to the fields of high-end equipment manufacturing such as aviation and aerospace, and in particular to a method for imaging damage of a reinforced beam structure in the whole area based on guided wave A0 mode. Background Art

[0002] Advanced composite materials have the advantages of high specific strength, high specific stiffness, designable performance, and good fatigue performance. They are widely used in high-end equipment fields such as modern aerospace. Composite reinforced beams reduce the overall weight of the structure, which is of great significance to current aircraft. Advanced composite materials are used in the main load-bearing or secondary load-bearing structures of aircraft to change the aeroelastic properties of the aircraft and improve flight performance. Due to the complex service environment, such as variable loads, moisture, and chemical corrosion, delamination damage will accumulate inside the structure over time, which will affect the mechanical properties of composite reinforced structures. At present, ultrasonic detection technology has attracted widespread attention as an effective composite material detection method.

[0003] In recent years, nondestructive testing technology has made significant progress, including methods based on acoustic emission, ultrasonic guided waves, and structural vibration ultrasound, each with its own advantages and disadvantages. The acoustic emission-based method has high sensitivity and can detect potential damage, but the classification is complex, it cannot show the degree of damage, and it is easily disturbed by environmental noise. Ultrasonic guided wave detection has a long propagation distance and low attenuation. It is often used for adhesive damage detection and is suitable for large-area detection, but damage location, classification, and severity require complex data analysis, which is limited by the sensor network, and the damage location and structure affect the effectiveness. The structural vibration ultrasonic method has low noise and can detect the location and size of damage, but the sensitivity is limited, and the detection effect is affected by the layering position and structural design. The phased array detection method can scan a large area and can instantly visualize and quantitatively characterize the damage, but the damage types are limited, the operation of complex curved structures is complicated, a coupling agent is required, and it is difficult to adapt to complex environments.

[0004] Guided waves have a wide propagation range, low attenuation, rich modal information, and are sensitive to small damage. Combined with non-contact measurement of laser vibrometer, they have the advantages of flexible scanning range, short time, high spatial resolution, strong adaptability to complex structures, and high online real-time performance. They can obtain the full wave field and multi-modal information of the measured structure in a short time. Its reliability and accuracy are constantly improving, providing a safe, convenient and effective online damage monitoring possibility for reinforced composite materials. Laser-excited ultrasonic signals have weak energy and short propagation distance, making it difficult to cover a large area. At the same time, the use of piezoelectric sensors as receiving sources is limited by the number of sensors and can only detect fixed sensor network areas, and has poor adaptability to complex structures. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a method for imaging multi-layered damage in the whole area of ​​a reinforced beam structure based on the guided wave A0 mode. The method of the present invention uses the laser scanning detection technology based on the guided wave A0 mode as a means to develop a fast and efficient visualization imaging technology to achieve quantitative detection of multi-layered damage in the whole area of ​​a composite reinforced beam structure.

[0006] The technical solution adopted by the present invention is:

[0007] The full-area multi-layered damage imaging method of a reinforced beam structure based on guided wave A0 mode of the present invention comprises:

[0008] S1: Build a laser non-contact scanning system based on the guided wave A0 mode, use epoxy resin glue to stick the piezoelectric transducer PZT (Piezoelectric Ceramic Transducer) on the surface of a composite reinforced beam structure with several different types of delamination damage, and electrically connect the piezoelectric transducer PZT to the laser non-contact scanning system based on the guided wave A0 mode.

[0009] S2: Generate an A0 modal waveguide signal through a laser non-contact scanning system and propagate it inside the composite reinforced beam structure. Detect the two-dimensional waveguide response signal in the composite reinforced beam structure through the laser non-contact scanning system, then obtain the filtered signal after signal filtering, and then set a specific window function to extract the two-dimensional data set of the A0 modal wave field in the filtered signal, and transform the two-dimensional data set of the A0 modal wave field into a three-dimensional data set of the A0 modal wave field.

[0010] S3: Construct a specific full-area multi-layered damage imaging model, obtain the A0 modal wave field curvature in the three-dimensional wave field data set and input it into the full-area multi-layered damage imaging model for processing. After processing, the full-area multi-layered damage imaging model outputs the imaging results of different types of delamination damage in the composite reinforced beam structure, and realizes full-area multi-layered damage imaging of the reinforced beam structure.

[0011] In the step S1, the laser non-contact scanning system based on the guided wave A0 mode includes a power amplifier, a signal generator, an oscilloscope, a laser vibrometer and a two-dimensional mobile platform. The piezoelectric transducer PZT, the power amplifier and the signal generator are electrically connected in sequence. The laser vibrometer is fixed on the two-dimensional mobile platform. The oscilloscope and the laser vibrometer are electrically connected. The composite material reinforced beam structure is fixed on the two-dimensional mobile platform and faces the laser vibrometer. The laser detection light emitted by the laser vibrometer is perpendicular to the detection surface of the composite material reinforced beam structure.

[0012] In the step S2, a waveguide signal of the A0 mode is generated by a signal generator of the laser non-contact scanning system, and then the waveguide signal is propagated to the inside of the composite material reinforced beam structure through the piezoelectric transducer PZT after power amplification by the power amplifier; the two-dimensional mobile platform is controlled to drive the composite material reinforced beam structure to move, so that the laser vibrometer scans the composite material reinforced beam structure with a Z-shaped laser scanning trajectory, and the two-dimensional waveguide response signal obtained by the scanning is displayed on the oscilloscope.

[0013] In the step S1, different types of delamination damage of the composite material reinforced beam structure include delamination damage at a curved surface position, a flat surface position and a side bending position.

[0014] In the step S2, the signal filtering process is specifically to perform bandpass filtering on the two-dimensional waveguide response signal to obtain a filtered signal, filter out irrelevant noise signals, and improve the signal-to-noise ratio.

[0015] In step S3, the specific full-area multi-layered injury imaging model is as follows:

[0016]

[0017] w A0 [x,y,T A0 ]=[(v A0 [x+1,y,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x-1,y,T A0 ])] / Δx 2 +[(v A0 [x,y+1,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x,y-1,T A0 ])] / Δy 2

[0018] Among them, EMAP A0 [] represents the A0 modal space energy distribution of the composite reinforced beam structure, that is, the imaging result of the delamination damage, x and y represent the coordinate points in the X direction and Y direction of the composite reinforced beam structure, x = 1, 2, ... N, y = 1, 2, ... M, M and N represent the total number of coordinate points in the X direction and Y direction of the composite reinforced beam structure, respectively; t A0Indicates the time corresponding to the maximum value of A0 mode, T A0 Indicates the width of the window function; w A0 [] represents the A0 modal wave field curvature of the composite reinforced beam structure; v A0 [] represents the A0 modal wave field of the composite reinforced beam structure; Δx and Δy represent the scanning intervals in the X and Y directions of the composite reinforced beam structure, respectively.

[0019] The A0 modal wave field of the composite reinforced beam structure is as follows:

[0020] v A0 [x,y,T A0 ]=v[x,y,t]*W(T A0 )

[0021]

[0022] Where, v[] represents the three-dimensional data set of A0 mode wave field, t represents time, t=1,2, … T, T represents the total scanning time; W() represents the window function.

[0023] The beneficial effects of the present invention are:

[0024] The method of the invention can perform layered damage detection on the entire area of ​​a large reinforced beam structure, improve the detection efficiency of a large composite reinforced beam structure, and provide a method for realizing automated detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the detection object and its damage of the present invention;

[0026] Figure 2 Schematic diagram of the window function of the present invention;

[0027] Figure 3 A schematic diagram of the detection process of the detection model of the present invention;

[0028] Figure 4 The whole-area delamination damage imaging diagram of the reinforced beam of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The full-area multi-layered damage imaging method of the reinforced beam structure based on the guided wave A0 mode of the present invention is specifically as follows:

[0031] First, a laser non-contact scanning system based on the guided wave A0 mode is built, and the piezoelectric transducer PZT is pasted on the surface of a composite reinforced beam structure with several different types of delamination damage using epoxy resin glue, and the piezoelectric transducer PZT is electrically connected to the laser non-contact scanning system based on the guided wave A0 mode. Different types of delamination damage of the composite reinforced beam structure include delamination damage at the curved surface position, the plane position and the side bending position. The laser non-contact scanning system based on the guided wave A0 mode includes a power amplifier, a signal generator, an oscilloscope, a laser vibrometer and a two-dimensional mobile platform. The piezoelectric transducer PZT, the power amplifier and the signal generator are electrically connected in sequence, the laser vibrometer is fixed on the two-dimensional mobile platform, the oscilloscope and the laser vibrometer are electrically connected, the composite reinforced beam structure is fixed on the two-dimensional mobile platform and faces the laser vibrometer, and the laser detection light emitted by the laser vibrometer is perpendicular to the detection surface of the composite reinforced beam structure.

[0032] Then, the A0 modal waveguide signal is generated by the laser non-contact scanning system and propagated inside the composite reinforced beam structure. The two-dimensional waveguide response signal in the composite reinforced beam structure is detected by the laser non-contact scanning system, and then the signal is filtered to obtain the filtered signal. Then, a specific window function is set to extract the two-dimensional data set of the A0 modal wave field in the filtered signal, and the two-dimensional data set of the A0 modal wave field is transformed into a three-dimensional data set of the A0 modal wave field. The signal filtering process is specifically to perform bandpass filtering on the two-dimensional waveguide response signal to obtain the filtered signal, filter out irrelevant noise signals, and improve the signal-to-noise ratio.

[0033] The signal generator of the laser non-contact scanning system generates a waveguide signal in the A0 mode, which is then amplified by a power amplifier and propagated to the inside of the composite material reinforced beam structure through the piezoelectric transducer PZT. The two-dimensional mobile platform is controlled to move the composite material reinforced beam structure, so that the laser vibrometer scans the composite material reinforced beam structure with a Z-shaped laser scanning trajectory, and the two-dimensional waveguide response signal obtained by the scanning is displayed on the oscilloscope.

[0034] Then, a specific full-area multi-layered damage imaging model is constructed, and the A0 modal wave field curvature is obtained in the three-dimensional wave field data set and input into the full-area multi-layered damage imaging model for processing. After processing, the full-area multi-layered damage imaging model outputs the imaging results of different types of delamination damage in the composite reinforced beam structure, and realizes the full-area multi-layered damage imaging of the reinforced beam structure. The specific full-area multi-layered damage imaging model is as follows:

[0035]

[0036] w A0 [x,y,T A0 ]=[(v A0[x+1,y,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x-1,y,T A0 ])] / Δx 2 +[(v A0 [x,y+1,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x,y-1,T A0 ])] / Δy 2

[0037] Among them, EMAP A0 [] represents the A0 modal space energy distribution of the composite reinforced beam structure, that is, the imaging result of the delamination damage, x and y represent the coordinate points in the X direction and Y direction of the composite reinforced beam structure, x = 1, 2, ... N, y = 1, 2, ... M, M and N represent the total number of coordinate points in the X direction and Y direction of the composite reinforced beam structure, respectively; t A0 Indicates the time corresponding to the maximum value of A0 mode, T A0 Indicates the width of the window function; w A0 [] represents the A0 modal wave field curvature of the composite reinforced beam structure; v A0 [] represents the A0 modal wave field of the composite reinforced beam structure; Δx and Δy represent the scanning intervals in the X and Y directions of the composite reinforced beam structure, respectively.

[0038] The A0 modal wave field of the composite reinforced beam structure is as follows:

[0039] v A0 [x,y,T A0 ]=v[x,y,t]*W(T A0 )

[0040]

[0041] Where, v[] represents the three-dimensional data set of A0 mode wave field, t represents time, t=1,2, … T, T represents the total scanning time; W() represents the window function.

[0042] The specific embodiments of the present invention are as follows:

[0043] First, a laser scanning system based on the guided wave A0 mode was built. The inspection object was a composite reinforced beam structure with multiple layered damages. It was made of carbon fiber composite material through hot pressing process, with a ply order of 0° and a material density of 1600kg / m 3 There are three different delamination damages in the reinforced beam area of ​​the composite material, including the internal delamination damage of the reinforced beam corner, the internal delamination damage of the reinforced beam top and the internal delamination damage of the reinforced beam side. The piezoelectric transducer PZT is pasted on the surface of the reinforced plate using epoxy resin glue, such as Figure 1 shown.

[0044] Then, the damage imaging method proposed in the present invention is used to detect the full-area layered damage imaging of the composite reinforced beam structure, as follows:

[0045] Firstly, the signal generator, power amplifier and piezoelectric transducer PZT are electrically connected. The signal generator generates a Lamb wave excitation signal of a specific frequency of 100kHz, which is amplified by the power amplifier. The piezoelectric transducer excites the generated guided wave to propagate in the composite reinforced beam structure. Due to the frequency modulation characteristics of the guided wave, the guided wave mode amplitudes of different frequencies are different. The excitation frequency with a larger A0 mode amplitude is selected. At a frequency of 100kHz, the A0 mode propagates in the curved surface with a small group velocity change and a large amplitude.

[0046] Then the composite material reinforced beam structure is fixed in front of the laser vibrometer, the detection surface is perpendicular to the detection light, and the laser vibrometer scanning trajectory is designed by programming the two-dimensional mobile platform. At the same time, the detection light scanning point is initialized. The programming mainly includes the scanning speed, scanning interval and scanning direction. The oscilloscope and the laser vibrometer are electrically connected to collect signals, and the oscilloscope sampling frequency and sampling time length are set. The sampling signal is averaged 500 times to improve the signal-to-noise ratio. The laser vibrometer detection light is perpendicular to the full area of ​​the reinforced beam.

[0047] Then, the low-frequency noise signal is filtered out by the signal filtering method, and the window function is set to 1.2 times the length of the excitation signal, which can effectively intercept the A0 mode. Figure 2 As shown, in order to obtain the strongest wavefield information of the A0 mode, the two-dimensional waveguide A0 mode wavefield information dataset is transformed into a three-dimensional waveguide A0 mode wavefield information dataset.

[0048] Finally, according to the three-dimensional waveguide A0 mode information data set, the wavefield curvature of the A0 mode is obtained using the wavefield curvature equation, and the wavefield energy is calculated through the wavefield curvature energy spectrum function, as shown in Figure 3 As shown, firstly, the full-area guided wave information of the reinforced beam is collected, then the sensitive mode A0 response signal, then the sensitive mode A0 guided wave field information, then the sensitive mode A0 guided wave field curvature, and finally the energy spectrum layered damage imaging of the composite reinforced beam structure is realized using the method proposed in the present invention, as shown in FIG. Figure 4As shown, it can be seen that the method of the present invention can detect the internal delamination damage of the reinforced beam corner, the internal delamination damage of the reinforced beam top and the internal delamination damage of the reinforced beam side, which proves the reliability of the method proposed in the present invention.

[0049] It can be seen from the embodiments that the present invention establishes the wave field curvature through a laser non-contact scanning detection method based on the guided wave A0 mode through shorter A0 mode information, does not require a complex sensing intelligent layer, does not require contact detection, is adaptable to complex reinforced structures, and meets the needs of delamination damage detection of composite reinforced beam structures.

Claims

1. A method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode, characterized in that: include: S1: Build a laser non-contact scanning system based on guided wave A0 mode, use epoxy resin glue to stick the piezoelectric transducer on the surface of the composite reinforced beam structure with several different types of delamination damage, and electrically connect the piezoelectric transducer to the laser non-contact scanning system based on guided wave A0 mode; S2: Generate an A0 modal guided wave signal through a laser non-contact scanning system and propagate it inside the composite reinforced beam structure, detect the two-dimensional guided wave response signal in the composite reinforced beam structure through the laser non-contact scanning system, and then obtain a filtered signal after signal filtering, and then set a specific window function to extract the A0 modal wave field two-dimensional data set in the filtered signal, and transform the A0 modal wave field two-dimensional data set into an A0 modal wave field three-dimensional data set; S3: Construct a specific full-area multi-layered damage imaging model, obtain the A0 modal wave field curvature in the three-dimensional wave field data set and input it into the full-area multi-layered damage imaging model for processing. After processing, the full-area multi-layered damage imaging model outputs the imaging results of different types of delamination damage in the composite reinforced beam structure, and realizes full-area multi-layered damage imaging of the reinforced beam structure.

2. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In the step S1, the laser non-contact scanning system based on the guided wave A0 mode includes a power amplifier, a signal generator, an oscilloscope, a laser vibrometer and a two-dimensional mobile platform. The piezoelectric transducer, the power amplifier and the signal generator are electrically connected in sequence. The laser vibrometer is fixed on the two-dimensional mobile platform. The oscilloscope and the laser vibrometer are electrically connected. The composite material reinforced beam structure is fixed on the two-dimensional mobile platform and faces the laser vibrometer. The laser detection light emitted by the laser vibrometer is perpendicular to the detection surface of the composite material reinforced beam structure.

3. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 2, characterized in that: In the step S2, a waveguide signal of the A0 mode is generated by a signal generator of the laser non-contact scanning system, and then the waveguide signal is propagated to the inside of the composite material reinforced beam structure through a piezoelectric transducer after power amplification by a power amplifier; the two-dimensional mobile platform is controlled to drive the composite material reinforced beam structure to move, so that the laser vibrometer scans the composite material reinforced beam structure with a Z-shaped laser scanning trajectory, and the two-dimensional waveguide response signal obtained by the scanning is displayed on an oscilloscope.

4. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In the step S1, different types of delamination damage of the composite material reinforced beam structure include delamination damage at a curved surface position, a flat surface position and a side bending position.

5. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In the step S2, the signal filtering process is specifically to perform bandpass filtering on the two-dimensional waveguide response signal to obtain a filtered signal.

6. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In step S3, the specific full-area multi-layered injury imaging model is as follows: w A0 [x,y,T A0 ]=[(v A0 [x+1,y,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x-1,y,T A0 ])] / Δx 2 +[(v A0 [x,y+1,T A0 ]-v A0 [x,y,T A0 ])-(v A0 [x,y,T A0 ]-v A0 [x,y-1,T A0 ])] / Δy 2 Among them, EMAP A0 [] represents the A0 modal space energy distribution of the composite reinforced beam structure, that is, the imaging result of the delamination damage. x and y represent the coordinate points in the X and Y directions of the composite reinforced beam structure, respectively. x=1,2, … N,y=1,2, … M, M and N represent the total number of coordinate points in the X and Y directions of the composite reinforced beam structure, respectively; t A0 Indicates the time corresponding to the maximum value of A0 mode, T A0 Indicates the width of the window function; w A0 [] represents the A0 modal wave field curvature of the composite reinforced beam structure; v A0 [] represents the A0 modal wave field of the composite reinforced beam structure; Δx and Δy represent the scanning intervals in the X and Y directions of the composite reinforced beam structure, respectively.

7. The method for full-area multi-layered damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 6, characterized in that: The A0 modal wave field of the composite reinforced beam structure is as follows: v A0 [x,y,T A0 ]=v[x,y,t]*W(T A0 ) Where, v[] represents the three-dimensional data set of A0 mode wave field, t represents time, t=1,2, … T, T represents the total scanning time; W() represents the window function.

Images