Full-area multi-layer damage imaging method for reinforced beam structures based on guided wave A0 mode

Abstract

The present invention discloses a method for imaging full-area multi-layered damage of a reinforced beam structure based on the guided wave A0 mode. The method comprises: generating an A0 mode guided wave signal through a laser non-contact scanning system and propagating it inside a composite reinforced beam structure and detecting a two-dimensional guided wave response signal; performing signal filtering processing and then setting a specific window function to extract the two-dimensional A0 modal wave field data set from the filtered signal and convert it into a three-dimensional data set; constructing a specific full-area multi-layered damage imaging model, obtaining the A0 modal wave field curvature and inputting it into the model for processing, and outputting imaging results of different types of layered damage. The method of the present invention can perform layered damage detection on large reinforced beam structures, improve the detection efficiency of large composite reinforced beam structures, and provide ideas for realizing automated 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. In particular, it relates to a method for imaging damage of a reinforced beam structure in a full area and in multiple layers based on the guided wave A0 mode. Background Art

[0002] Advanced composite materials offer advantages such as high specific strength, high specific stiffness, customizable performance, and excellent fatigue resistance, making them widely used in high-end equipment such as modern aerospace. Reinforced composite beams are crucial for modern aircraft, reducing the overall weight of the structure. The use of advanced composite materials in primary or secondary load-bearing aircraft structures alters the aircraft's aeroelastic properties and improves flight performance. Due to complex service environments, such as fluctuating loads, moisture, and chemical corrosion, delamination damage accumulates over time within the structure, impacting the mechanical properties of reinforced composite structures. Currently, ultrasonic testing technology, as an effective composite material testing method, has attracted widespread attention.

[0003] In recent years, significant progress has been made in non-destructive testing technology, 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 interfered 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 delamination 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, coupling agents are 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 using laser vibrometers, they offer advantages such as flexible scanning range, short scanning times, high spatial resolution, strong adaptability to complex structures, and high online real-time performance. They can quickly acquire full wavefield and multimodal information about the structure under test. Their reliability and accuracy are continuously improving, providing safe, convenient, and effective online damage monitoring for reinforced composite materials. However, laser-excited ultrasonic signals have weak energy and short propagation distances, making them difficult to cover large areas. Furthermore, the use of piezoelectric sensors as receiving sources is limited by the number of sensors available, limiting detection to fixed sensor network areas and limiting adaptability to complex structures. Summary of the Invention

[0005] To address the challenges presented in the prior art, the present invention provides a method for imaging full-area, multi-layer damage in reinforced beam structures using the guided wave A0 mode. This method leverages laser scanning detection technology based on the guided wave A0 mode to develop a fast and efficient visualization imaging technique, enabling quantitative detection of full-area, multi-layer damage in composite reinforced beam structures.

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

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

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

[0009] S2: A guided wave signal of the A0 mode is generated by a laser non-contact scanning system and propagated inside the composite reinforced beam structure. The two-dimensional guided wave response signal in the composite reinforced beam structure is detected by the laser non-contact scanning system. The signal is then filtered to obtain a filtered signal. A specific window function is then set to extract the two-dimensional A0 modal wave field dataset from the filtered signal, and the two-dimensional A0 modal wave field dataset is transformed into a three-dimensional A0 modal wave field dataset.

[0010] S3: Construct a specific full-area multi-layered damage imaging model. Obtain the A0 modal wavefield curvature from the three-dimensional wavefield dataset 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 imaging results of different types of delamination damage in the composite reinforced beam structure, realizing full-area multi-layered damage imaging of the reinforced beam structure.

[0011] In 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 directly 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 step S2, a waveguide signal in the A0 mode is generated by a signal generator of the laser non-contact scanning system, and then the waveguide signal is amplified by a power amplifier and then propagated to the interior of the composite material reinforced beam structure through a piezoelectric transducer PZT; 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.

[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 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 damage 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 on the composite reinforced beam structure, respectively.

[0019] The A0 modal wave field of the composite material 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 present invention can perform layered damage detection on the entire area of ​​a large reinforced beam structure, improve the detection efficiency of large composite material reinforced beam structures, and provide ideas for realizing automated detection. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0030] The full-area multi-layer damage imaging method of a reinforced beam structure based on 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 was constructed. A piezoelectric transducer (PZT) was attached to the surface of a composite reinforced beam structure with several different types of delamination damage using epoxy resin glue. The piezoelectric transducer (PZT) was then electrically connected to the laser non-contact scanning system based on the guided wave A0 mode. The different types of delamination damage in the composite reinforced beam structure include delamination damage on curved surfaces, flat surfaces, and lateral bends. 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), power amplifier, and signal generator are electrically connected in sequence. The laser vibrometer is fixed to the two-dimensional mobile platform. The oscilloscope and laser vibrometer are electrically connected. The composite 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 inspection surface of the composite reinforced beam structure.

[0032] A non-contact laser scanning system then generates an A0 modal guided wave signal, which propagates within the composite reinforced beam structure. The system then detects the two-dimensional guided wave response signal within the composite reinforced beam structure. Signal filtering is then performed to obtain a filtered signal. A specific window function is then set to extract the two-dimensional A0 modal wavefield dataset from the filtered signal, transforming the two-dimensional A0 modal wavefield dataset into a three-dimensional A0 modal wavefield dataset. Specifically, the signal filtering process involves bandpass filtering the two-dimensional guided wave response signal to obtain a filtered signal, removing irrelevant noise and improving the signal-to-noise ratio.

[0033] The signal generator of the laser non-contact scanning system generates an A0 mode guided wave signal, which is then amplified by a power amplifier and propagated to the interior of the composite reinforced beam structure through a piezoelectric transducer (PZT). The two-dimensional mobile platform is controlled to move the composite reinforced beam structure, allowing the laser vibrometer to scan the composite reinforced beam structure with a Z-shaped laser scanning trajectory, and the two-dimensional guided wave response signal obtained from the scanning is displayed on an oscilloscope.

[0034] Then, a specific full-area multi-layered damage imaging model is constructed. The A0 modal wavefield curvature is obtained from the three-dimensional wavefield dataset and input into the full-area multi-layered damage imaging model for processing. After processing, the full-area multi-layered damage imaging model outputs imaging results of different types of delamination damage in the composite reinforced beam structure, realizing 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 on 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 delamination damages. The structure was made of carbon fiber composite material through a hot pressing process, with a ply order of 0° and a material density of 1600 kg / m 3 ,There are three different delamination damages in the composite reinforced beam area, including delamination damage inside the reinforced beam corner, delamination damage inside the reinforced beam top and delamination damage inside 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 perform full-area layered damage imaging detection on the composite reinforced beam structure, specifically as follows:

[0045] First, the signal generator, power amplifier and piezoelectric transducer PZT are electrically connected. The signal generator generates a Lamb wave excitation signal with 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] The composite reinforced beam structure is then fixed in front of the laser vibrometer, with the detection surface perpendicular to the detection light. The laser vibrometer scanning trajectory is designed by programming the two-dimensional mobile platform, and the detection light scanning points are initialized at the same time. The programming mainly includes the scanning speed, scanning interval and scanning direction. The oscilloscope and 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, such as 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, based on the three-dimensional guided wave A0 modal information data set, the wavefield curvature of the A0 mode is obtained using the wavefield curvature equation, and the wavefield energy is calculated using the wavefield curvature energy spectrum function, as shown in the following example: Figure 3 As shown in FIG, 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 internal delamination damage at the corner of the reinforced beam, internal delamination damage at the top of the reinforced beam, and internal delamination damage at the side of the reinforced beam, 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 modal information. It does not require a complex sensing intelligent layer and 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-layer damage imaging of reinforced beam structures based on guided wave A0 mode, characterized by: include: S1: Build a laser non-contact scanning system based on the guided wave A0 mode. Use epoxy resin glue to attach a piezoelectric transducer to the surface of a composite reinforced beam structure with several different types of delamination damage. Then electrically connect the piezoelectric transducer to the laser non-contact scanning system based on the guided wave A0 mode. S2: Generate an A0 modal guided wave signal through a non-contact laser scanning system and propagate it within the composite reinforced beam structure. Detect the two-dimensional guided wave response signal in the composite reinforced beam structure through the non-contact laser scanning system. Then, filter the signal to obtain a filtered signal. A window function is then set to extract the two-dimensional A0 modal wave field dataset from the filtered signal. The two-dimensional A0 modal wave field dataset is then transformed into a three-dimensional A0 modal wave field dataset. S3: Construct a full-area multi-layered damage imaging model. The A0 modal wavefield curvature is obtained from the three-dimensional wavefield dataset and input into the full-area multi-layered damage imaging model for processing. After processing, the full-area multi-layered damage imaging model outputs imaging results of different types of delamination damage in the composite reinforced beam structure, achieving full-area multi-layered damage imaging of the reinforced beam structure. In step S3, the full-area multi-layered damage imaging model is specifically as follows: in, It represents the A0 modal space energy distribution of the composite reinforced beam structure, that is, the imaging result of delamination damage. x and y represent the coordinate points in the X and Y directions of the composite reinforced beam structure, respectively. , , M and N represent the total number of coordinate points in the X and Y directions of the composite reinforced beam structure, respectively; Indicates the time corresponding to the maximum value of A0 mode, Indicates the width of the window function; represents the A0 modal wave field curvature of the composite reinforced beam structure; Represents the A0 modal wave field of the composite reinforced beam structure; and They represent the scanning intervals in the X and Y directions on the composite reinforced beam structure respectively; The A0 modal wave field of the composite material reinforced beam structure is as follows: in, represents the A0 mode wave field three-dimensional data set, t represents time, , T represents the total scanning time; Represents the window function.

2. The method for full-area multi-layer damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In 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 directly 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-layer damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 2, characterized in that: In step S2, a waveguide signal in the A0 mode is generated by a signal generator of the laser non-contact scanning system, and then the waveguide signal is amplified by a power amplifier and then propagated to the interior of the composite material reinforced beam structure through a piezoelectric transducer; 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-layer 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-layer damage imaging of a reinforced beam structure based on guided wave A0 mode according to claim 1, characterized in that: In step S2, the signal filtering process is specifically to perform bandpass filtering on the two-dimensional waveguide response signal to obtain a filtered signal.

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